GltfLoader.java

/*
 * Copyright (c) 2009-2023 jMonkeyEngine
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 * * Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 * * Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
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 * * Neither the name of 'jMonkeyEngine' nor the names of its contributors
 *   may be used to endorse or promote products derived from this software
 *   without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
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 */
package com.jme3.scene.plugins.gltf;

import com.google.gson.*;
import com.google.gson.stream.JsonReader;
import com.jme3.anim.*;
import com.jme3.asset.*;
import com.jme3.material.Material;
import com.jme3.material.RenderState;
import com.jme3.math.*;
import com.jme3.renderer.Camera;
import com.jme3.renderer.queue.RenderQueue;
import com.jme3.scene.*;
import com.jme3.scene.control.CameraControl;
import com.jme3.scene.mesh.MorphTarget;
import static com.jme3.scene.plugins.gltf.GltfUtils.*;
import com.jme3.texture.Texture;
import com.jme3.texture.Texture2D;
import com.jme3.util.IntMap;
import com.jme3.util.mikktspace.MikktspaceTangentGenerator;
import java.io.*;
import java.net.URLDecoder;
import java.nio.Buffer;
import java.nio.FloatBuffer;
import java.util.*;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * GLTF 2.0 loader
 * Created by Nehon on 07/08/2017.
 */
public class GltfLoader implements AssetLoader {

    private static final Logger logger = Logger.getLogger(GltfLoader.class.getName());

    // Data cache for already parsed JME objects
    private final Map<String, Object[]> dataCache = new HashMap<>();
    private JsonArray scenes;
    private JsonArray nodes;
    private JsonArray meshes;
    private JsonArray accessors;
    private JsonArray bufferViews;
    private JsonArray buffers;
    private JsonArray materials;
    private JsonArray textures;
    private JsonArray images;
    private JsonArray samplers;
    private JsonArray animations;
    private JsonArray skins;
    private JsonArray cameras;

    private Material defaultMat;
    private AssetInfo info;
    private JsonObject docRoot;
    private Node rootNode;

    private final FloatArrayPopulator floatArrayPopulator = new FloatArrayPopulator();
    private final Vector3fArrayPopulator vector3fArrayPopulator = new Vector3fArrayPopulator();
    private final QuaternionArrayPopulator quaternionArrayPopulator = new QuaternionArrayPopulator();
    private final Matrix4fArrayPopulator matrix4fArrayPopulator = new Matrix4fArrayPopulator();
    private final Map<String, MaterialAdapter> defaultMaterialAdapters = new HashMap<>();
    private final CustomContentManager customContentManager = new CustomContentManager();
    private boolean useNormalsFlag = false;

    Map<SkinData, List<Spatial>> skinnedSpatials = new HashMap<>();
    IntMap<SkinBuffers> skinBuffers = new IntMap<>();

    public GltfLoader() {
        defaultMaterialAdapters.put("pbrMetallicRoughness", new PBRMetalRoughMaterialAdapter());
    }

    @Override
    public Object load(AssetInfo assetInfo) throws IOException {
        return loadFromStream(assetInfo, assetInfo.openStream());
    }

    protected Object loadFromStream(AssetInfo assetInfo, InputStream stream) throws IOException {
        try {
            dataCache.clear();
            info = assetInfo;
            skinnedSpatials.clear();
            rootNode = new Node();

            if (defaultMat == null) {
                defaultMat = new Material(assetInfo.getManager(), "Common/MatDefs/Light/PBRLighting.j3md");
                defaultMat.setColor("BaseColor", ColorRGBA.White);
                defaultMat.setFloat("Metallic", 0f);
                defaultMat.setFloat("Roughness", 1f);
            }

            docRoot = JsonParser.parseReader(new JsonReader(new InputStreamReader(stream))).getAsJsonObject();

            JsonObject asset = docRoot.getAsJsonObject().get("asset").getAsJsonObject();
            getAsString(asset, "generator");
            String version = getAsString(asset, "version");
            String minVersion = getAsString(asset, "minVersion");
            if (!isSupported(version, minVersion)) {
                logger.log(Level.SEVERE, "Gltf Loader doesn''t support this gltf version: {0}{1}", new Object[]{version, minVersion != null ? ("/" + minVersion) : ""});
            }

            scenes = docRoot.getAsJsonArray("scenes");
            nodes = docRoot.getAsJsonArray("nodes");
            meshes = docRoot.getAsJsonArray("meshes");
            accessors = docRoot.getAsJsonArray("accessors");
            bufferViews = docRoot.getAsJsonArray("bufferViews");
            buffers = docRoot.getAsJsonArray("buffers");
            materials = docRoot.getAsJsonArray("materials");
            textures = docRoot.getAsJsonArray("textures");
            images = docRoot.getAsJsonArray("images");
            samplers = docRoot.getAsJsonArray("samplers");
            animations = docRoot.getAsJsonArray("animations");
            skins = docRoot.getAsJsonArray("skins");
            cameras = docRoot.getAsJsonArray("cameras");

            customContentManager.init(this);

            readSkins();
            readCameras();

            JsonPrimitive defaultScene = docRoot.getAsJsonPrimitive("scene");

            readScenes(defaultScene, rootNode);

            rootNode = customContentManager.readExtensionAndExtras("root", docRoot, rootNode);

            // Loading animations
            if (animations != null) {
                for (int i = 0; i < animations.size(); i++) {
                    readAnimation(i);
                }
            }

            setupControls();

            // only one scene let's not return the root.
            if (rootNode.getChildren().size() == 1) {
                Node child = (Node) rootNode.getChild(0);
                // Migrate lights that were in the parent to the child.
                rootNode.getLocalLightList().forEach(child::addLight);
                rootNode = child;
            }
            // no name for the scene... let's set the file name.
            if (rootNode.getName() == null) {
                rootNode.setName(assetInfo.getKey().getName());
            }
            return rootNode;
        } catch (Exception e) {
            throw new AssetLoadException("An error occurred loading " + assetInfo.getKey().getName(), e);
        } finally {
            stream.close();
        }
    }

    private void setDefaultParams(Material mat) {
        mat.setColor("BaseColor", ColorRGBA.White);
        mat.setFloat("Metallic", 0f);
        mat.setFloat("Roughness", 1f);
    }

    private boolean isSupported(String version, String minVersion) {
        return "2.0".equals(version);
    }

    public void readScenes(JsonPrimitive defaultScene, Node rootNode) throws IOException {
        if (scenes == null) {
            // no scene... lets handle this later...
            throw new AssetLoadException("Gltf files with no scene is not yet supported");
        }

        for (JsonElement scene : scenes) {
            Node sceneNode = new Node();
            // Specs say that only the default scene should be rendered.
            // If there are several scenes, they are attached to the rootScene, but they are culled.
            sceneNode.setCullHint(Spatial.CullHint.Always);

            sceneNode.setName(getAsString(scene.getAsJsonObject(), "name"));
            // If the scene is empty, ignore it.
            if (!scene.getAsJsonObject().has("nodes")) {
                continue;
            }
            JsonArray sceneNodes = scene.getAsJsonObject().getAsJsonArray("nodes");
            sceneNode = customContentManager.readExtensionAndExtras("scene", scene, sceneNode);
            rootNode.attachChild(sceneNode);
            for (JsonElement node : sceneNodes) {
                readChild(sceneNode, node);
            }
        }

        // Setting the default scene cul hint to inherit.
        int activeChild = 0;
        if (defaultScene != null) {
            activeChild = defaultScene.getAsInt();
        }
        rootNode.getChild(activeChild).setCullHint(Spatial.CullHint.Inherit);
    }

    public Object readNode(int nodeIndex) throws IOException {
        Object obj = fetchFromCache("nodes", nodeIndex, Object.class);
        if (obj != null) {
            if (obj instanceof JointWrapper) {
                // the node can be a previously loaded bone let's return it
                return obj;
            } else {
                // If a spatial is referenced several times, it may be attached to different parents,
                // and it's not possible in JME, so we have to clone it.
                return ((Spatial) obj).clone();
            }
        }
        Spatial spatial;
        JsonObject nodeData = nodes.get(nodeIndex).getAsJsonObject();
        JsonArray children = nodeData.getAsJsonArray("children");
        Integer meshIndex = getAsInteger(nodeData, "mesh");
        if (meshIndex != null) {
            assertNotNull(meshes, "Can't find any mesh data, yet a node references a mesh");

            // there is a mesh in this node, however gltf
            // can split meshes in primitives (some kind of sub meshes),
            // We don't have this in JME, so we have to make one Mesh and one Geometry for each primitive.
            Geometry[] primitives = readMeshPrimitives(meshIndex);
            if (primitives.length == 1 && children == null) {
                // only one geometry, let's not wrap it in another node unless the node has children.
                spatial = primitives[0];
            } else {
                // several geometries, let's make a parent Node and attach them to it
                Node node = new Node();
                for (Geometry primitive : primitives) {
                    node.attachChild(primitive);
                }
                spatial = node;
            }
            spatial.setName(readMeshName(meshIndex));

        } else {
            // no mesh, we have a node. Can be a camera node or a regular node.
            Integer camIndex = getAsInteger(nodeData, "camera");
            if (camIndex != null) {
                Camera cam = fetchFromCache("cameras", camIndex, Camera.class);
                CameraNode node = new CameraNode(null, cam);
                node.setControlDir(CameraControl.ControlDirection.SpatialToCamera);
                spatial = node;
            } else {
                Node node = new Node();
                spatial = node;
            }
        }

        Integer skinIndex = getAsInteger(nodeData, "skin");
        if (skinIndex != null) {
            SkinData skinData = fetchFromCache("skins", skinIndex, SkinData.class);
            if (skinData != null) {
                List<Spatial> spatials = skinnedSpatials.get(skinData);
                spatials.add(spatial);
                skinData.used = true;
            }
        }

        spatial.setLocalTransform(readTransforms(nodeData));

        if (spatial.getName() == null) {
            spatial.setName(getAsString(nodeData.getAsJsonObject(), "name"));
        }

        spatial = customContentManager.readExtensionAndExtras("node", nodeData, spatial);

        addToCache("nodes", nodeIndex, spatial, nodes.size());
        return spatial;
    }

    private void readChild(Spatial parent, JsonElement nodeIndex) throws IOException {
        Object loaded = readNode(nodeIndex.getAsInt());
        if (loaded instanceof Spatial) {
            Spatial spatial = ((Spatial) loaded);
            ((Node) parent).attachChild(spatial);
            JsonObject nodeElem = nodes.get(nodeIndex.getAsInt()).getAsJsonObject();
            JsonArray children = nodeElem.getAsJsonArray("children");
            if (children != null) {
                for (JsonElement child : children) {
                    readChild(spatial, child);
                }
            }
        } else if (loaded instanceof JointWrapper) {
            // parent is the Armature Node, we have to apply its transforms to the root bone's animation data
            JointWrapper bw = (JointWrapper) loaded;
            bw.isRoot = true;
            SkinData skinData = fetchFromCache("skins", bw.skinIndex, SkinData.class);
            if (skinData == null) {
                return;
            }
            skinData.parent = parent;
        }
    }

    public Transform readTransforms(JsonObject nodeData) {
        Transform transform = new Transform();
        JsonArray matrix = nodeData.getAsJsonArray("matrix");
        if (matrix != null) {
            // transforms are given as a mat4
            float[] tmpArray = new float[16];
            for (int i = 0; i < tmpArray.length; i++) {
                tmpArray[i] = matrix.get(i).getAsFloat();
            }
            // creates a row major matrix from color major data
            Matrix4f mat = new Matrix4f(tmpArray);
            transform.fromTransformMatrix(mat);
            return transform;
        }
        // no matrix transforms: no transforms or transforms givens as translation/rotation/scale
        JsonArray translation = nodeData.getAsJsonArray("translation");
        if (translation != null) {
            transform.setTranslation(
                    translation.get(0).getAsFloat(),
                    translation.get(1).getAsFloat(),
                    translation.get(2).getAsFloat());
        }
        JsonArray rotation = nodeData.getAsJsonArray("rotation");
        if (rotation != null) {
            transform.setRotation(new Quaternion(
                    rotation.get(0).getAsFloat(),
                    rotation.get(1).getAsFloat(),
                    rotation.get(2).getAsFloat(),
                    rotation.get(3).getAsFloat()));
        }
        JsonArray scale = nodeData.getAsJsonArray("scale");
        if (scale != null) {
            transform.setScale(
                    scale.get(0).getAsFloat(),
                    scale.get(1).getAsFloat(),
                    scale.get(2).getAsFloat());
        }

        return transform;
    }

    public Geometry[] readMeshPrimitives(int meshIndex) throws IOException {
        Geometry[] geomArray = (Geometry[]) fetchFromCache("meshes", meshIndex, Object.class);
        if (geomArray != null) {
            // cloning the geoms.
            Geometry[] geoms = new Geometry[geomArray.length];
            for (int i = 0; i < geoms.length; i++) {
                geoms[i] = geomArray[i].clone(false);
            }
            return geoms;
        }
        JsonObject meshData = meshes.get(meshIndex).getAsJsonObject();
        JsonArray primitives = meshData.getAsJsonArray("primitives");
        assertNotNull(primitives, "Can't find any primitives in mesh " + meshIndex);
        String name = getAsString(meshData, "name");

        geomArray = new Geometry[primitives.size()];
        int index = 0;
        for (JsonElement primitive : primitives) {
            JsonObject meshObject = primitive.getAsJsonObject();
            Mesh mesh = new Mesh();
            addToCache("mesh", 0, mesh, 1);
            Integer mode = getAsInteger(meshObject, "mode");
            mesh.setMode(getMeshMode(mode));
            Integer indices = getAsInteger(meshObject, "indices");
            if (indices != null) {
                mesh.setBuffer(readAccessorData(indices, new VertexBufferPopulator(VertexBuffer.Type.Index)));
            }
            JsonObject attributes = meshObject.getAsJsonObject("attributes");
            assertNotNull(attributes, "No attributes defined for mesh " + mesh);

            skinBuffers.clear();

            for (Map.Entry<String, JsonElement> entry : attributes.entrySet()) {
                // special case for joints and weights buffer.
                // If there are more than 4 bones per vertex, there might be several of them
                // we need to read them all and to keep only the 4 that have the most weight on the vertex.
                String bufferType = entry.getKey();
                if (bufferType.startsWith("JOINTS")) {
                    SkinBuffers buffs = getSkinBuffers(bufferType);
                    SkinBuffers buffer
                            = readAccessorData(entry.getValue().getAsInt(), new JointArrayPopulator());
                    buffs.joints = buffer.joints;
                    buffs.componentSize = buffer.componentSize;
                } else if (bufferType.startsWith("WEIGHTS")) {
                    SkinBuffers buffs = getSkinBuffers(bufferType);
                    buffs.weights = readAccessorData(entry.getValue().getAsInt(), new FloatArrayPopulator());
                } else {
                    VertexBuffer vb = readAccessorData(entry.getValue().getAsInt(),
                            new VertexBufferPopulator(getVertexBufferType(bufferType)));
                    if (vb != null) {
                        mesh.setBuffer(vb);
                    }
                }
            }
            handleSkinningBuffers(mesh, skinBuffers);

            if (mesh.getBuffer(VertexBuffer.Type.BoneIndex) != null) {
                // the mesh has some skinning let's create needed buffers for HW skinning
                // creating empty buffers for HW skinning
                // the buffers will be setup if ever used.
                VertexBuffer weightsHW = new VertexBuffer(VertexBuffer.Type.HWBoneWeight);
                VertexBuffer indicesHW = new VertexBuffer(VertexBuffer.Type.HWBoneIndex);
                // setting usage to cpuOnly so that the buffer is not sent empty to the GPU
                indicesHW.setUsage(VertexBuffer.Usage.CpuOnly);
                weightsHW.setUsage(VertexBuffer.Usage.CpuOnly);
                mesh.setBuffer(weightsHW);
                mesh.setBuffer(indicesHW);
                mesh.generateBindPose();
            }

            // Read morph target names
            LinkedList<String> targetNames = new LinkedList<>();
            if (meshData.has("extras") && meshData.getAsJsonObject("extras").has("targetNames")) {
                JsonArray targetNamesJson = meshData.getAsJsonObject("extras").getAsJsonArray("targetNames");
                for (JsonElement target : targetNamesJson) {
                    targetNames.add(target.getAsString());
                }
            }

            // Read morph targets
            JsonArray targets = meshObject.getAsJsonArray("targets");
            if (targets != null) {
                for (JsonElement target : targets) {
                    MorphTarget morphTarget = new MorphTarget();
                    if (targetNames.size() > 0) {
                        morphTarget.setName(targetNames.pop());
                    }
                    for (Map.Entry<String, JsonElement> entry : target.getAsJsonObject().entrySet()) {
                        String bufferType = entry.getKey();
                        VertexBuffer.Type type = getVertexBufferType(bufferType);
                        VertexBuffer vb = readAccessorData(entry.getValue().getAsInt(),
                                new VertexBufferPopulator(type));
                        if (vb != null) {
                            morphTarget.setBuffer(type, (FloatBuffer) vb.getData());
                        }
                    }
                    mesh.addMorphTarget(morphTarget);
                }
            }

            // Read mesh extras
            mesh = customContentManager.readExtensionAndExtras("primitive", meshObject, mesh);
            Geometry geom = new Geometry(null, mesh);

            Integer materialIndex = getAsInteger(meshObject, "material");
            if (materialIndex == null) {
                geom.setMaterial(defaultMat);
            } else {
                useNormalsFlag = false;
                geom.setMaterial(readMaterial(materialIndex));
                if (geom.getMaterial().getAdditionalRenderState().getBlendMode()
                        == RenderState.BlendMode.Alpha) {
                    // Alpha blending is enabled for this material. Let's place the geom in the transparent bucket.
                    geom.setQueueBucket(RenderQueue.Bucket.Transparent);
                }
                if (useNormalsFlag && mesh.getBuffer(VertexBuffer.Type.Tangent) == null) {
                    // No tangent buffer, but there is a normal map, we have to generate them using MiiktSpace
                    MikktspaceTangentGenerator.generate(geom);
                }
            }

            if (name != null) {
                geom.setName(name + (primitives.size() > 1 ? ("_" + index) : ""));
            }

            geom.updateModelBound();
            geomArray[index] = geom;
            index++;
        }

        geomArray = customContentManager.readExtensionAndExtras("mesh", meshData, geomArray);

        addToCache("meshes", meshIndex, geomArray, meshes.size());
        return geomArray;
    }

    private SkinBuffers getSkinBuffers(String bufferType) {
        int bufIndex = getIndex(bufferType);
        SkinBuffers buffs = skinBuffers.get(bufIndex);
        if (buffs == null) {
            buffs = new SkinBuffers();
            skinBuffers.put(bufIndex, buffs);
        }
        return buffs;
    }

    private <R> R readAccessorData(int accessorIndex, Populator<R> populator) throws IOException {
        assertNotNull(accessors, "No accessor attribute in the gltf file");

        JsonObject accessor = accessors.get(accessorIndex).getAsJsonObject();
        Integer bufferViewIndex = getAsInteger(accessor, "bufferView");
        int byteOffset = getAsInteger(accessor, "byteOffset", 0);
        Integer componentType = getAsInteger(accessor, "componentType");
        assertNotNull(componentType, "No component type defined for accessor " + accessorIndex);
        Integer count = getAsInteger(accessor, "count");
        assertNotNull(count, "No count attribute defined for accessor " + accessorIndex);
        String type = getAsString(accessor, "type");
        assertNotNull(type, "No type attribute defined for accessor " + accessorIndex);

        boolean normalized = getAsBoolean(accessor, "normalized", false);

        // TODO min / max...don't know what to do about them.
        // TODO sparse

        R data = populator.populate(bufferViewIndex, componentType, type, count, byteOffset, normalized);
        data = customContentManager.readExtensionAndExtras("accessor", accessor, data);
        return data;
    }

    public Object readBuffer(Integer bufferViewIndex, int byteOffset, int count, Object store,
            int numComponents, VertexBuffer.Format format) throws IOException {
        JsonObject bufferView = bufferViews.get(bufferViewIndex).getAsJsonObject();
        Integer bufferIndex = getAsInteger(bufferView, "buffer");
        assertNotNull(bufferIndex, "No buffer defined for bufferView " + bufferViewIndex);
        int bvByteOffset = getAsInteger(bufferView, "byteOffset", 0);
        Integer byteLength = getAsInteger(bufferView, "byteLength");
        assertNotNull(byteLength, "No byte length defined for bufferView " + bufferViewIndex);
        int byteStride = getAsInteger(bufferView, "byteStride", 0);

        // target defines ELEMENT_ARRAY_BUFFER or ARRAY_BUFFER,
        // but we already know that since we know we load the index buffer or any other...
        // Not sure it's useful for us, but I guess it's useful when you map data directly to the GPU.
        // int target = getAsInteger(bufferView, "target", 0);

        byte[] data = readData(bufferIndex);
        data = customContentManager.readExtensionAndExtras("bufferView", bufferView, data);

        if (store == null) {
            store = new byte[byteLength];
        }

        if (count == -1) {
            count = byteLength;
        }

        populateBuffer(store, data, count, byteOffset + bvByteOffset, byteStride, numComponents, format);

        return store;
    }

    public byte[] readData(int bufferIndex) throws IOException {
        assertNotNull(buffers, "No buffer defined");

        JsonObject buffer = buffers.get(bufferIndex).getAsJsonObject();
        String uri = getAsString(buffer, "uri");
        Integer bufferLength = getAsInteger(buffer, "byteLength");
        assertNotNull(bufferLength, "No byteLength defined for buffer " + bufferIndex);
        byte[] data = (byte[]) fetchFromCache("buffers", bufferIndex, Object.class);
        if (data != null) {
            return data;
        }
        data = getBytes(bufferIndex, uri, bufferLength);

        data = customContentManager.readExtensionAndExtras("buffer", buffer, data);

        addToCache("buffers", bufferIndex, data, buffers.size());
        return data;
    }

    protected byte[] getBytes(int bufferIndex, String uri, Integer bufferLength) throws IOException {
        byte[] data;
        if (uri != null) {
            if (uri.startsWith("data:")) {
                // base 64 embed data
                data = Base64.getDecoder().decode(uri.substring(uri.indexOf(",") + 1));
            } else {
                // external file let's load it
                String decoded = decodeUri(uri);
                if (!decoded.endsWith(".bin")) {
                    throw new AssetLoadException(
                            "Cannot load " + decoded + ", a .bin extension is required.");
                }

                BinDataKey key = new BinDataKey(info.getKey().getFolder() + decoded);
                InputStream input = (InputStream) info.getManager().loadAsset(key);
                data = new byte[bufferLength];
                DataInputStream dataStream = new DataInputStream(input);
                dataStream.readFully(data);
                dataStream.close();
            }
        } else {
            // no URI this should not happen in a gltf file, only in glb files.
            throw new AssetLoadException("Buffer " + bufferIndex + " has no uri");
        }
        return data;
    }

    public Material readMaterial(int materialIndex) throws IOException {
        assertNotNull(materials, "There is no material defined yet a mesh references one");

        JsonObject matData = materials.get(materialIndex).getAsJsonObject();
        JsonObject pbrMat = matData.getAsJsonObject("pbrMetallicRoughness");

        MaterialAdapter adapter = null;

        if (pbrMat != null) {
            adapter = getAdapterForMaterial(info, "pbrMetallicRoughness");
            if (adapter == null) {
                adapter = defaultMaterialAdapters.get("pbrMetallicRoughness");
            }
            adapter.init(info.getManager());
        }

        adapter = customContentManager.readExtensionAndExtras("material", matData, adapter);

        if (adapter == null) {
            logger.log(Level.WARNING,
                    "Couldn't find any matching material definition for material " + materialIndex);
            adapter = defaultMaterialAdapters.get("pbrMetallicRoughness");
            adapter.init(info.getManager());
            setDefaultParams(adapter.getMaterial());
        }

        Integer metallicRoughnessIndex = null;
        if (pbrMat != null) {
            adapter.setParam("baseColorFactor", getAsColor(pbrMat, "baseColorFactor", ColorRGBA.White));
            adapter.setParam("metallicFactor", getAsFloat(pbrMat, "metallicFactor", 1f));
            adapter.setParam("roughnessFactor", getAsFloat(pbrMat, "roughnessFactor", 1f));
            adapter.setParam("baseColorTexture", readTexture(pbrMat.getAsJsonObject("baseColorTexture")));
            adapter.setParam("metallicRoughnessTexture",
                    readTexture(pbrMat.getAsJsonObject("metallicRoughnessTexture")));
            JsonObject metallicRoughnessJson = pbrMat.getAsJsonObject("metallicRoughnessTexture");
            metallicRoughnessIndex = metallicRoughnessJson != null ? getAsInteger(metallicRoughnessJson, "index") : null;            
        }

        adapter.getMaterial().setName(getAsString(matData, "name"));
        adapter.setParam("emissiveFactor", getAsColor(matData, "emissiveFactor", ColorRGBA.Black));
        String alphaMode = getAsString(matData, "alphaMode");
        adapter.setParam("alphaMode", alphaMode);
        if (alphaMode != null && alphaMode.equals("MASK")) {
            adapter.setParam("alphaCutoff", getAsFloat(matData, "alphaCutoff"));
        }
        adapter.setParam("doubleSided", getAsBoolean(matData, "doubleSided"));
        Texture2D normal = readTexture(matData.getAsJsonObject("normalTexture"));
        adapter.setParam("normalTexture", normal);
        if (normal != null) {
            useNormalsFlag = true;

            JsonObject normalTexture = matData.getAsJsonObject("normalTexture");
            Float normalScale = getAsFloat(normalTexture, "scale");
            if (normalScale != null) {
                adapter.setParam("normalScale", normalScale);
            }
        }
        JsonObject occlusionJson = matData.getAsJsonObject("occlusionTexture");
        Integer occlusionIndex = occlusionJson != null ? getAsInteger(occlusionJson, "index") : null;
        if (occlusionIndex != null && occlusionIndex.equals(metallicRoughnessIndex)) {
            adapter.getMaterial().setBoolean("AoPackedInMRMap", true);
        } else {        
            adapter.setParam("occlusionTexture", readTexture(matData.getAsJsonObject("occlusionTexture")));
        }
        adapter.setParam("emissiveTexture", readTexture(matData.getAsJsonObject("emissiveTexture")));

        return adapter.getMaterial();
    }

    public void readCameras() throws IOException {
        if (cameras == null) {
            return;
        }
        for (int i = 0; i < cameras.size(); i++) {
            // Can't access resolution here... actually it's a shame we can't access settings from anywhere.
            // users will have to call resize on the camera.
            Camera cam = new Camera(1, 1);

            JsonObject camObj = cameras.get(i).getAsJsonObject();
            String type = getAsString(camObj, "type");
            assertNotNull(type, "No type defined for camera");
            JsonObject camData = camObj.getAsJsonObject(type);
            if (type.equals("perspective")) {
                float aspectRatio = getAsFloat(camData, "aspectRation", 1f);
                Float yfov = getAsFloat(camData, "yfov");
                assertNotNull(yfov, "No yfov for perspective camera");
                Float zNear = getAsFloat(camData, "znear");
                assertNotNull(zNear, "No znear for perspective camera");
                Float zFar = getAsFloat(camData, "zfar", zNear * 1000f);

                cam.setFrustumPerspective(yfov * FastMath.RAD_TO_DEG, aspectRatio, zNear, zFar);
                cam = customContentManager.readExtensionAndExtras("camera.perspective", camData, cam);

            } else {
                Float xmag = getAsFloat(camData, "xmag");
                assertNotNull(xmag, "No xmag for orthographic camera");
                Float ymag = getAsFloat(camData, "ymag");
                assertNotNull(ymag, "No ymag for orthographic camera");
                Float zNear = getAsFloat(camData, "znear");
                assertNotNull(zNear, "No znear for orthographic camera");
                Float zFar = getAsFloat(camData, "zfar", zNear * 1000f);
                assertNotNull(zFar, "No zfar for orthographic camera");

                cam.setParallelProjection(true);
                cam.setFrustum(zNear, zFar, -xmag, xmag, ymag, -ymag);

                cam = customContentManager.readExtensionAndExtras("camera.orthographic", camData, cam);
            }
            cam = customContentManager.readExtensionAndExtras("camera", camObj, cam);
            addToCache("cameras", i, cam, cameras.size());
        }
    }

    public Texture2D readTexture(JsonObject texture) throws IOException {
        return readTexture(texture, false);
    }

    public Texture2D readTexture(JsonObject texture, boolean flip) throws IOException {
        if (texture == null) {
            return null;
        }
        Integer textureIndex = getAsInteger(texture, "index");
        assertNotNull(textureIndex, "Texture has no index");
        assertNotNull(textures, "There are no textures, yet one is referenced by a material");

        JsonObject textureData = textures.get(textureIndex).getAsJsonObject();
        Integer sourceIndex = getAsInteger(textureData, "source");
        Integer samplerIndex = getAsInteger(textureData, "sampler");

        Texture2D texture2d = readImage(sourceIndex, flip);

        if (samplerIndex != null) {
            texture2d = readSampler(samplerIndex, texture2d);
        } else {
            texture2d.setWrap(Texture.WrapMode.Repeat);
        }

        texture2d = customContentManager.readExtensionAndExtras("texture", texture, texture2d);

        return texture2d;
    }

    public Texture2D readImage(int sourceIndex, boolean flip) throws IOException {
        if (images == null) {
            throw new AssetLoadException("No image defined");
        }

        JsonObject image = images.get(sourceIndex).getAsJsonObject();
        String uri = getAsString(image, "uri");
        Integer bufferView = getAsInteger(image, "bufferView");
        String mimeType = getAsString(image, "mimeType");
        Texture2D result;
        if (uri == null) {
            assertNotNull(bufferView, "Image " + sourceIndex + " should either have an uri or a bufferView");
            assertNotNull(mimeType, "Image " + sourceIndex + " should have a mimeType");
            byte[] data = (byte[]) readBuffer(bufferView, 0, -1, null, 1, VertexBuffer.Format.Byte);
            String extension = mimeType.split("/")[1];
            TextureKey key = new TextureKey("image" + sourceIndex + "." + extension, flip);
            result = (Texture2D) info.getManager().loadAssetFromStream(key, new ByteArrayInputStream(data));

        } else if (uri.startsWith("data:")) {
            // base64 encoded image
            String[] uriInfo = uri.split(",");
            byte[] data = Base64.getDecoder().decode(uriInfo[1]);
            String headerInfo = uriInfo[0].split(";")[0];
            String extension = headerInfo.split("/")[1];
            TextureKey key = new TextureKey("image" + sourceIndex + "." + extension, flip);
            result = (Texture2D) info.getManager().loadAssetFromStream(key, new ByteArrayInputStream(data));
        } else {
            // external file image
            String decoded = decodeUri(uri);
            TextureKey key = new TextureKey(info.getKey().getFolder() + decoded, flip);
            Texture tex = info.getManager().loadTexture(key);
            result = (Texture2D) tex;
        }
        return result;
    }

    public void readAnimation(int animationIndex) throws IOException {
        JsonObject animation = animations.get(animationIndex).getAsJsonObject();
        JsonArray channels = animation.getAsJsonArray("channels");
        JsonArray samplers = animation.getAsJsonArray("samplers");
        String name = getAsString(animation, "name");
        assertNotNull(channels, "No channels for animation " + name);
        assertNotNull(samplers, "No samplers for animation " + name);

        // temp data storage of track data
        TrackData[] tracks = new TrackData[nodes.size()];
        boolean hasMorphTrack = false;

        for (JsonElement channel : channels) {
            JsonObject target = channel.getAsJsonObject().getAsJsonObject("target");

            Integer targetNode = getAsInteger(target, "node");
            String targetPath = getAsString(target, "path");
            if (targetNode == null) {
                // no target node for the channel, specs say to ignore the channel.
                continue;
            }
            assertNotNull(targetPath, "No target path for channel");
//
//            if (targetPath.equals("weights")) {
//                // Morph animation, not implemented in JME, let's warn the user and skip the channel
//                logger.log(Level.WARNING,
//                    "Morph animation is not supported by JME yet, skipping animation track");
//                continue;
//            }

            TrackData trackData = tracks[targetNode];
            if (trackData == null) {
                trackData = new TrackData();
                tracks[targetNode] = trackData;
            }

            Integer samplerIndex = getAsInteger(channel.getAsJsonObject(), "sampler");
            assertNotNull(samplerIndex, "No animation sampler provided for channel");
            JsonObject sampler = samplers.get(samplerIndex).getAsJsonObject();
            Integer timeIndex = getAsInteger(sampler, "input");
            assertNotNull(timeIndex, "No input accessor Provided for animation sampler");
            Integer dataIndex = getAsInteger(sampler, "output");
            assertNotNull(dataIndex, "No output accessor Provided for animation sampler");

            String interpolation = getAsString(sampler, "interpolation");
            if (interpolation == null || !interpolation.equals("LINEAR")) {
                // JME anim system only supports Linear interpolation (will be possible with monkanim though)
                // TODO rework this once monkanim is core,
                // or allow a hook for animation loading to fit custom animation systems
                logger.log(Level.WARNING, "JME only supports linear interpolation for animations");
            }

            trackData = customContentManager.readExtensionAndExtras("animation.sampler", sampler, trackData);

            float[] times = fetchFromCache("accessors", timeIndex, float[].class);
            if (times == null) {
                times = readAccessorData(timeIndex, floatArrayPopulator);
                addToCache("accessors", timeIndex, times, accessors.size());
            }

            if (targetPath.equals("translation")) {
                trackData.timeArrays.add(new TrackData.TimeData(times, TrackData.Type.Translation));
                Vector3f[] translations = readAccessorData(dataIndex, vector3fArrayPopulator);
                trackData.translations = translations;
            } else if (targetPath.equals("scale")) {
                trackData.timeArrays.add(new TrackData.TimeData(times, TrackData.Type.Scale));
                Vector3f[] scales = readAccessorData(dataIndex, vector3fArrayPopulator);
                trackData.scales = scales;
            } else if (targetPath.equals("rotation")) {
                trackData.timeArrays.add(new TrackData.TimeData(times, TrackData.Type.Rotation));
                Quaternion[] rotations = readAccessorData(dataIndex, quaternionArrayPopulator);
                trackData.rotations = rotations;
            } else {
                trackData.timeArrays.add(new TrackData.TimeData(times, TrackData.Type.Morph));
                float[] weights = readAccessorData(dataIndex, floatArrayPopulator);
                trackData.weights = weights;
                hasMorphTrack = true;
            }
            tracks[targetNode] = customContentManager.readExtensionAndExtras("channel", channel, trackData);
        }

        if (name == null) {
            name = "anim_" + animationIndex;
        }

        List<Spatial> spatials = new ArrayList<>();
        AnimClip anim = new AnimClip(name);
        List<AnimTrack> aTracks = new ArrayList<>();
        int skinIndex = -1;

        List<Joint> usedJoints = new ArrayList<>();
        for (int i = 0; i < tracks.length; i++) {
            TrackData trackData = tracks[i];
            if (trackData == null || trackData.timeArrays.isEmpty()) {
                continue;
            }
            trackData.update();
            Object node = fetchFromCache("nodes", i, Object.class);
            if (node instanceof Spatial) {
                Spatial s = (Spatial) node;
                spatials.add(s);
                if (trackData.rotations != null || trackData.translations != null
                        || trackData.scales != null) {
                    TransformTrack track = new TransformTrack(s, trackData.times,
                            trackData.translations, trackData.rotations, trackData.scales);
                    aTracks.add(track);
                }
                if (trackData.weights != null && s instanceof Geometry) {
                    Geometry g = (Geometry) s;
                    int nbMorph = g.getMesh().getMorphTargets().length;
//                    for (int k = 0; k < trackData.weights.length; k++) {
//                        System.err.print(trackData.weights[k] + ",");
//                        if(k % nbMorph == 0 && k!=0){
//                            System.err.println(" ");
//                        }
//                    }
                    MorphTrack track = new MorphTrack(g, trackData.times, trackData.weights, nbMorph);
                    aTracks.add(track);
                }
            } else if (node instanceof JointWrapper) {
                JointWrapper jw = (JointWrapper) node;
                usedJoints.add(jw.joint);

                if (skinIndex == -1) {
                    skinIndex = jw.skinIndex;
                } else {
                    // Check if all joints affected by this animation are from the same skin,
                    // the track will be skipped.
                    if (skinIndex != jw.skinIndex) {
                        logger.log(Level.WARNING, "Animation " + animationIndex + " (" + name
                                + ") applies to joints that are not from the same skin: skin "
                                + skinIndex + ", joint " + jw.joint.getName()
                                + " from skin " + jw.skinIndex);
                        continue;
                    }
                }

                TransformTrack track = new TransformTrack(jw.joint, trackData.times,
                        trackData.translations, trackData.rotations, trackData.scales);
                aTracks.add(track);
            }
        }

        // Check each bone to see if their local pose is different from their bind pose.
        // If it is, we ensure that the bone has an animation track,
        // else JME way of applying anim transforms will apply the bind pose to those bones,
        // instead of the local pose that is supposed to be the default
        if (skinIndex != -1) {
            SkinData skin = fetchFromCache("skins", skinIndex, SkinData.class);
            for (Joint joint : skin.joints) {
                if (!usedJoints.contains(joint)) {
                    // create a track
                    float[] times = new float[]{0};

                    Vector3f[] translations = new Vector3f[]{joint.getLocalTranslation()};
                    Quaternion[] rotations = new Quaternion[]{joint.getLocalRotation()};
                    Vector3f[] scales = new Vector3f[]{joint.getLocalScale()};
                    TransformTrack track = new TransformTrack(joint, times, translations, rotations, scales);
                    aTracks.add(track);
                }
            }
        }

        anim.setTracks(aTracks.toArray(new AnimTrack[aTracks.size()]));
        anim = customContentManager.readExtensionAndExtras("animations", animation, anim);

        if (skinIndex != -1) {
            // we have an armature animation.
            SkinData skin = fetchFromCache("skins", skinIndex, SkinData.class);
            skin.animComposer.addAnimClip(anim);
        }

        if (!spatials.isEmpty()) {
            if (skinIndex != -1) {
                // there are some spatial or morph tracks in this bone animation... or the other way around.
                // Let's add the spatials in the skinnedSpatials.
                SkinData skin = fetchFromCache("skins", skinIndex, SkinData.class);
                List<Spatial> spat = skinnedSpatials.get(skin);
                spat.addAll(spatials);
                // the animControl will be added in the setupControls();
                if (hasMorphTrack && skin.morphControl == null) {
                    skin.morphControl = new MorphControl();
                }
            } else {
                // Spatial animation
                Spatial spatial = null;
                if (spatials.size() == 1) {
                    spatial = spatials.get(0);
                } else {
                    spatial = findCommonAncestor(spatials);
                }

                AnimComposer composer = spatial.getControl(AnimComposer.class);
                if (composer == null) {
                    composer = new AnimComposer();
                    spatial.addControl(composer);
                }
                composer.addAnimClip(anim);
                if (hasMorphTrack && spatial.getControl(MorphControl.class) == null) {
                    spatial.addControl(new MorphControl());
                }
            }
        }
    }

    public Texture2D readSampler(int samplerIndex, Texture2D texture) throws IOException {
        if (samplers == null) {
            throw new AssetLoadException("No samplers defined");
        }
        JsonObject sampler = samplers.get(samplerIndex).getAsJsonObject();
        Texture.MagFilter magFilter = getMagFilter(getAsInteger(sampler, "magFilter"));
        Texture.MinFilter minFilter = getMinFilter(getAsInteger(sampler, "minFilter"));
        Texture.WrapMode wrapS = getWrapMode(getAsInteger(sampler, "wrapS"));
        Texture.WrapMode wrapT = getWrapMode(getAsInteger(sampler, "wrapT"));

        if (magFilter != null) {
            texture.setMagFilter(magFilter);
        }
        if (minFilter != null) {
            texture.setMinFilter(minFilter);
        }
        texture.setWrap(Texture.WrapAxis.S, wrapS);
        texture.setWrap(Texture.WrapAxis.T, wrapT);

        texture = customContentManager.readExtensionAndExtras("texture.sampler", sampler, texture);

        return texture;
    }

    public void readSkins() throws IOException {
        if (skins == null) {
            // no skins, no bone animation.
            return;
        }
        List<JsonArray> allJoints = new ArrayList<>();
        for (int index = 0; index < skins.size(); index++) {
            JsonObject skin = skins.get(index).getAsJsonObject();

            // Note that the "skeleton" index is intentionally ignored.
            // It's not mandatory and exporters tends to mix up how it should be used
            // because the specs are not clear.
            // Anyway we have other means to detect both armature structures and root bones.

            JsonArray jsonJoints = skin.getAsJsonArray("joints");
            assertNotNull(jsonJoints, "No joints defined for skin");
            int idx = allJoints.indexOf(jsonJoints);
            if (idx >= 0) {
                // skin already exists let's just set it in the cache
                SkinData sd = fetchFromCache("skins", idx, SkinData.class);
                addToCache("skins", index, sd, nodes.size());
                continue;
            } else {
                allJoints.add(jsonJoints);
            }

            // These inverse bind matrices, once inverted again,
            // will give us the real bind pose of the bones (in model space),
            // since the skeleton in not guaranteed to be exported in bind pose.
            Integer matricesIndex = getAsInteger(skin, "inverseBindMatrices");
            Matrix4f[] inverseBindMatrices = null;
            if (matricesIndex != null) {
                inverseBindMatrices = readAccessorData(matricesIndex, matrix4fArrayPopulator);
            } else {
                inverseBindMatrices = new Matrix4f[jsonJoints.size()];
                for (int i = 0; i < inverseBindMatrices.length; i++) {
                    inverseBindMatrices[i] = new Matrix4f();
                }
            }

            Joint[] joints = new Joint[jsonJoints.size()];
            for (int i = 0; i < jsonJoints.size(); i++) {
                int boneIndex = jsonJoints.get(i).getAsInt();
                Matrix4f inverseModelBindMatrix = inverseBindMatrices[i];
                joints[i] = readNodeAsBone(boneIndex, i, index, inverseModelBindMatrix);
            }

            for (int i = 0; i < jsonJoints.size(); i++) {
                findChildren(jsonJoints.get(i).getAsInt());
            }

            Armature armature = new Armature(joints);
            armature = customContentManager.readExtensionAndExtras("skin", skin, armature);
            SkinData skinData = new SkinData();
            skinData.joints = joints;
            skinData.skinningControl = new SkinningControl(armature);
            skinData.animComposer = new AnimComposer();
            addToCache("skins", index, skinData, nodes.size());
            skinnedSpatials.put(skinData, new ArrayList<Spatial>());

            armature.update();
            armature.saveInitialPose();
        }
    }

    public Joint readNodeAsBone(int nodeIndex, int jointIndex, int skinIndex, Matrix4f inverseModelBindMatrix)
            throws IOException {
        JointWrapper jointWrapper = fetchFromCache("nodes", nodeIndex, JointWrapper.class);
        if (jointWrapper != null) {
            return jointWrapper.joint;
        }
        JsonObject nodeData = nodes.get(nodeIndex).getAsJsonObject();
        String name = getAsString(nodeData, "name");
        if (name == null) {
            name = "Joint_" + nodeIndex;
        }
        Joint joint = new Joint(name);
        Transform boneTransforms = null;
        boneTransforms = readTransforms(nodeData);
        joint.setLocalTransform(boneTransforms);
        joint.setInverseModelBindMatrix(inverseModelBindMatrix);

        addToCache("nodes", nodeIndex, new JointWrapper(joint, jointIndex, skinIndex), nodes.size());

        return joint;
    }

    private void findChildren(int nodeIndex) throws IOException {
        JointWrapper jw = fetchFromCache("nodes", nodeIndex, JointWrapper.class);
        if (jw == null) {
            logger.log(Level.WARNING,
                    "No JointWrapper found for nodeIndex={0}.", nodeIndex);
            return;
        }

        JsonObject nodeData = nodes.get(nodeIndex).getAsJsonObject();
        JsonArray children = nodeData.getAsJsonArray("children");

        if (children != null) {
            for (JsonElement child : children) {
                int childIndex = child.getAsInt();
                if (jw.children.contains(childIndex)) {
                    // bone already has the child in its children
                    continue;
                }
                JointWrapper cjw = fetchFromCache("nodes", childIndex, JointWrapper.class);
                if (cjw != null) {
                    jw.joint.addChild(cjw.joint);
                    jw.children.add(childIndex);
                } else {
                    // The child might be a Node
                    // Creating a dummy node to read the subgraph
                    Node n = new Node();
                    readChild(n, child);
                    Spatial s = n.getChild(0);
                    // removing the spatial from the dummy node,
                    // it will be attached to the attachment node of the bone
                    s.removeFromParent();
                    jw.attachedSpatial = s;
                }
            }
        }
    }

    private void setupControls() {
        for (SkinData skinData : skinnedSpatials.keySet()) {
            List<Spatial> spatials = skinnedSpatials.get(skinData);
            if (spatials.isEmpty()) {
                continue;
            }
            Spatial spatial = skinData.parent;

            if (spatials.size() >= 1) {
                spatial = findCommonAncestor(spatials);
            }
//            if (spatial != skinData.parent) {
//                skinData.rootBoneTransformOffset = spatial.getWorldTransform().invert();
//                if (skinData.parent != null) {
//                    skinData.rootBoneTransformOffset.combineWithParent(skinData.parent.getWorldTransform());
//                }
//            }
            if (skinData.animComposer != null && skinData.animComposer.getSpatial() == null) {
                spatial.addControl(skinData.animComposer);
            }
            spatial.addControl(skinData.skinningControl);
            if (skinData.morphControl != null) {
                spatial.addControl(skinData.morphControl);
            }
        }

        for (int i = 0; i < nodes.size(); i++) {
            JointWrapper bw = fetchFromCache("nodes", i, JointWrapper.class);
            if (bw == null || bw.attachedSpatial == null) {
                continue;
            }
            String jointName = bw.joint.getName();
            SkinData skinData = fetchFromCache("skins", bw.skinIndex, SkinData.class);
            SkinningControl skinControl = skinData.skinningControl;
            if (skinControl.getSpatial() == null) {
                logger.log(Level.WARNING,
                        "No skinned Spatial for joint \"{0}\" -- will skin the model's root node!",
                        jointName);
                rootNode.addControl(skinControl);
            }
            skinControl.getAttachmentsNode(jointName).attachChild(bw.attachedSpatial);
        }
    }

    private String readMeshName(int meshIndex) {
        JsonObject meshData = meshes.get(meshIndex).getAsJsonObject();
        return getAsString(meshData, "name");
    }

    public <T> T fetchFromCache(String name, int index, Class<T> type) {
        Object[] data = dataCache.get(name);
        if (data == null) {
            return null;
        }
        try {
            T ret = type.cast(data[index]);
            return ret;
        } catch (ClassCastException e) {
            return null;
        }
    }

    public void addToCache(String name, int index, Object object, int maxLength) {
        Object[] data = dataCache.get(name);
        if (data == null) {
            data = new Object[maxLength];
            dataCache.put(name, data);
        }
        data[index] = object;
    }

    public AssetInfo getInfo() {
        return info;
    }

    public JsonObject getDocRoot() {
        return docRoot;
    }

    public Node getRootNode() {
        return rootNode;
    }

    private String decodeUri(String uri) {
        try {
            return URLDecoder.decode(uri, "UTF-8");
        } catch (UnsupportedEncodingException e) {
            return uri; // This would mean that UTF-8 is unsupported on the platform.
        }
    }

    public static class WeightData {
        float value;
        short index;
        int componentSize;

        public WeightData(float value, short index, int componentSize) {
            this.value = value;
            this.index = index;
            this.componentSize = componentSize;
        }
    }

    private class JointWrapper {
        Joint joint;
        int jointIndex;
        int skinIndex;
        boolean isRoot = false;
        Spatial attachedSpatial;
        List<Integer> children = new ArrayList<>();

        public JointWrapper(Joint joint, int jointIndex, int skinIndex) {
            this.joint = joint;
            this.jointIndex = jointIndex;
            this.skinIndex = skinIndex;
        }
    }

    private class SkinData {
        SkinningControl skinningControl;
        MorphControl morphControl;
        AnimComposer animComposer;
        Spatial spatial;
        Spatial parent;
        Transform rootBoneTransformOffset;
        Joint[] joints;
        boolean used = false;
    }

    public static class SkinBuffers {
        short[] joints;
        float[] weights;
        int componentSize;

        public SkinBuffers(short[] joints, int componentSize) {
            this.joints = joints;
            this.componentSize = componentSize;
        }

        public SkinBuffers() {}
    }

    private interface Populator<T> {
        T populate(Integer bufferViewIndex, int componentType, String type, int count, int byteOffset,
                boolean normalized) throws IOException;
    }

    private class VertexBufferPopulator implements Populator<VertexBuffer> {
        VertexBuffer.Type bufferType;

        public VertexBufferPopulator(VertexBuffer.Type bufferType) {
            this.bufferType = bufferType;
        }

        @Override
        public VertexBuffer populate(Integer bufferViewIndex, int componentType, String type, int count,
                int byteOffset, boolean normalized) throws IOException {
            if (bufferType == null) {
                logger.log(Level.WARNING, "could not assign data to any VertexBuffer type for buffer view {0}", bufferViewIndex);
                return null;
            }

            VertexBuffer vb = new VertexBuffer(bufferType);
            VertexBuffer.Format format = getVertexBufferFormat(componentType);
            VertexBuffer.Format originalFormat = format;
            if (normalized) {
                // Some float data can be packed into short buffers,
                // "normalized" means they have to be unpacked.
                // In that case the buffer is a FloatBuffer
                format = VertexBuffer.Format.Float;
            }
            int numComponents = getNumberOfComponents(type);

            Buffer buff = VertexBuffer.createBuffer(format, numComponents, count);
            int bufferSize = numComponents * count;
            if (bufferViewIndex == null) {
                // no referenced buffer, specs says to pad the buffer with zeros.
                padBuffer(buff, bufferSize);
            } else {
                readBuffer(bufferViewIndex, byteOffset, count, buff, numComponents, originalFormat);
            }

            if (bufferType == VertexBuffer.Type.Index) {
                numComponents = 3;
            }
            vb.setupData(VertexBuffer.Usage.Dynamic, numComponents, format, buff);

            return vb;
        }
    }

    private class FloatArrayPopulator implements Populator<float[]> {

        @Override
        public float[] populate(Integer bufferViewIndex, int componentType, String type, int count,
                int byteOffset, boolean normalized) throws IOException {
            int numComponents = getNumberOfComponents(type);
            int dataSize = numComponents * count;
            float[] data = new float[dataSize];

            if (bufferViewIndex == null) {
                // no referenced buffer, specs says to pad the data with zeros.
                padBuffer(data, dataSize);
            } else {
                readBuffer(bufferViewIndex, byteOffset, count, data, numComponents,
                        getVertexBufferFormat(componentType));
            }

            return data;
        }
    }
//
//    private class FloatGridPopulator implements Populator<float[]> {
//
//        @Override
//        public float[][] populate(Integer bufferViewIndex, int componentType, String type, int count,
//                int byteOffset, boolean normalized) throws IOException {
//
//            int numComponents = getNumberOfComponents(type);
//            int dataSize = numComponents * count;
//            float[] data = new float[dataSize];
//
//            if (bufferViewIndex == null) {
//                // no referenced buffer, specs says to pad the data with zeros.
//                padBuffer(data, dataSize);
//            } else {
//                readBuffer(bufferViewIndex, byteOffset, count, data, numComponents,
//                        getVertexBufferFormat(componentType));
//            }
//
//            return data;
//        }
//
//    }

    private class Vector3fArrayPopulator implements Populator<Vector3f[]> {

        @Override
        public Vector3f[] populate(Integer bufferViewIndex, int componentType, String type, int count,
                int byteOffset, boolean normalized) throws IOException {
            int numComponents = getNumberOfComponents(type);
            int dataSize = numComponents * count;
            Vector3f[] data = new Vector3f[count];

            if (bufferViewIndex == null) {
                // no referenced buffer, specs says to pad the data with zeros.
                padBuffer(data, dataSize);
            } else {
                readBuffer(bufferViewIndex, byteOffset, count, data, numComponents,
                        getVertexBufferFormat(componentType));
            }
            return data;
        }
    }

    private class QuaternionArrayPopulator implements Populator<Quaternion[]> {

        @Override
        public Quaternion[] populate(Integer bufferViewIndex, int componentType, String type, int count,
                int byteOffset, boolean normalized) throws IOException {
            int numComponents = getNumberOfComponents(type);
            int dataSize = numComponents * count;
            Quaternion[] data = new Quaternion[count];

            if (bufferViewIndex == null) {
                // no referenced buffer, specs says to pad the data with zeros.
                padBuffer(data, dataSize);
            } else {
                readBuffer(bufferViewIndex, byteOffset, count, data, numComponents,
                        getVertexBufferFormat(componentType));
            }

            return data;
        }
    }

    private class Matrix4fArrayPopulator implements Populator<Matrix4f[]> {

        @Override
        public Matrix4f[] populate(Integer bufferViewIndex, int componentType, String type, int count,
                int byteOffset, boolean normalized) throws IOException {
            int numComponents = getNumberOfComponents(type);
            int dataSize = numComponents * count;
            Matrix4f[] data = new Matrix4f[count];

            if (bufferViewIndex == null) {
                // no referenced buffer, specs says to pad the data with zeros.
                padBuffer(data, dataSize);
            } else {
                readBuffer(bufferViewIndex, byteOffset, count, data, numComponents,
                        getVertexBufferFormat(componentType));
            }

            return data;
        }
    }

    private class JointArrayPopulator implements Populator<SkinBuffers> {

        @Override
        public SkinBuffers populate(Integer bufferViewIndex, int componentType, String type, int count,
                int byteOffset, boolean normalized) throws IOException {
            int numComponents = getNumberOfComponents(type);

            // can be bytes or shorts.
            VertexBuffer.Format format = VertexBuffer.Format.Byte;
            if (componentType == 5123) {
                format = VertexBuffer.Format.Short;
            }

            int dataSize = numComponents * count;
            short[] data = new short[dataSize];

            if (bufferViewIndex == null) {
                // no referenced buffer, specs says to pad the data with zeros.
                padBuffer(data, dataSize);
            } else {
                readBuffer(bufferViewIndex, byteOffset, count, data, numComponents, format);
            }

            return new SkinBuffers(data, format.getComponentSize());
        }
    }
}