Add fast render path for SOGS spherical harmonics

src/scene/gsplat/gsplat-instance.js

@@ -2,7 +2,9 @@ import { Mat4 } from '../../core/math/mat4.js';
 import { Vec3 } from '../../core/math/vec3.js';
 import { CULLFACE_NONE, SEMANTIC_ATTR13, SEMANTIC_POSITION, PIXELFORMAT_R32U } from '../../platform/graphics/constants.js';
 import { MeshInstance } from '../mesh-instance.js';
+import { GSplatResolveSH } from './gsplat-resolve-sh.js';
 import { GSplatSorter } from './gsplat-sorter.js';
+import { GSplatSogsData } from './gsplat-sogs-data.js';
 import { ShaderMaterial } from '../materials/shader-material.js';
 import { BLEND_NONE, BLEND_PREMULTIPLIED } from '../constants.js';
 
@@ -34,13 +36,16 @@ class GSplatInstance {
 
     options = {};
 
-    /** @type {GSplatSorter | null} */
+    /** @type {GSplatSorter|null} */
     sorter = null;
 
     lastCameraPosition = new Vec3();
 
     lastCameraDirection = new Vec3();
 
+    /** @type {GSplatResolveSH|null} */
+    resolveSH = null;
+
     /**
      * List of cameras this instance is visible for. Updated every frame by the renderer.
      *
@@ -111,9 +116,17 @@ class GSplatInstance {
             // update splat count on the material
             this.material.setParameter('numSplats', count);
         });
+
+        // configure sogs sh resolve
+        const { gsplatData } = resource;
+        if (gsplatData instanceof GSplatSogsData && gsplatData.shBands > 0 && !gsplatData.fullSH) {
+            this.resolveSH = new GSplatResolveSH(resource.device, this);
+            this.material.setDefine('SH_BANDS', '0');
+        }
     }
 
     destroy() {
+        this.resolveSH?.destroy();
         this.material?.destroy();
         this.meshInstance?.destroy();
         this.sorter?.destroy();
@@ -212,6 +225,9 @@ class GSplatInstance {
             const camera = this.cameras[0];
             this.sort(camera._node);
 
+            // resolve spherical harmonics
+            this.resolveSH?.render(camera._node, this.meshInstance.node.getWorldTransform());
+
             // we get new list of cameras each frame
             this.cameras.length = 0;
         }