[Impeller] only use porter duff or vertices.uber for drawVertices. (#52345)

Simplifcation that will allow us to remove the special case position_color.vert and vertices.frag shaders, not done here because drawAtlas also needs to be updated. This  also fixes sparkle-party like rendering bugs where we incorrectly relied on a color filter.

The problem with doing advanced blends between the vertices with a color filters was three fold:

1. We would render incorrectly when vertices overlapped.
2. We had to disable MSAA to remove artifacts
3. The sub render pass was slow.

Below is an example of the incorrect rendering caused by overlapping vertices on the sparkle party app.

## Skia (Advanced blend)

![flutter_02](https://github.com/flutter/engine/assets/8975114/36cdd590-5b1e-4b9e-ae4d-cc187ba40bb6)

## Impeller (ToT)

![flutter_01](https://github.com/flutter/engine/assets/8975114/20ea5f42-6fb3-4f5e-b332-516ee904b8f6)

## Impeller w/ patch

![flutter_03](https://github.com/flutter/engine/assets/8975114/e88ccb6b-56ba-42de-8542-bbd94ba0fe44)

Fixes flutter/flutter#131345

Author: Jonah Williams

ci/licenses_golden/excluded_files

@@ -152,7 +152,6 @@
 ../../../flutter/impeller/entity/contents/host_buffer_unittests.cc
 ../../../flutter/impeller/entity/contents/test
 ../../../flutter/impeller/entity/contents/tiled_texture_contents_unittests.cc
-../../../flutter/impeller/entity/contents/vertices_contents_unittests.cc
 ../../../flutter/impeller/entity/entity_pass_target_unittests.cc
 ../../../flutter/impeller/entity/entity_pass_unittests.cc
 ../../../flutter/impeller/entity/entity_unittests.cc

impeller/aiks/canvas.cc

@@ -16,6 +16,7 @@
 #include "impeller/entity/contents/atlas_contents.h"
 #include "impeller/entity/contents/clip_contents.h"
 #include "impeller/entity/contents/color_source_contents.h"
+#include "impeller/entity/contents/content_context.h"
 #include "impeller/entity/contents/filters/filter_contents.h"
 #include "impeller/entity/contents/solid_rrect_blur_contents.h"
 #include "impeller/entity/contents/text_contents.h"
@@ -933,8 +934,19 @@ void Canvas::DrawVertices(const std::shared_ptr<VerticesGeometry>& vertices,
     return;
   }
 
-  // If there is are per-vertex colors, an image, and the blend mode
-  // is simple we can draw without a sub-renderpass.
+  // If the blend mode is destination don't bother to bind or create a texture.
+  if (blend_mode == BlendMode::kDestination) {
+    auto contents = std::make_shared<VerticesSimpleBlendContents>();
+    contents->SetBlendMode(blend_mode);
+    contents->SetAlpha(paint.color.alpha);
+    contents->SetGeometry(vertices);
+    entity.SetContents(paint.WithFilters(std::move(contents)));
+    AddRenderEntityToCurrentPass(std::move(entity));
+    return;
+  }
+
+  // If there is a texture, use this directly. Otherwise render the color
+  // source to a texture.
   if (std::optional<ImageData> maybe_image_data =
           GetImageColorSourceData(paint.color_source)) {
     const ImageData& image_data = maybe_image_data.value();
@@ -956,35 +968,35 @@ void Canvas::DrawVertices(const std::shared_ptr<VerticesGeometry>& vertices,
 
   std::shared_ptr<Contents> src_contents =
       src_paint.CreateContentsForGeometry(vertices);
-  if (vertices->HasTextureCoordinates()) {
-    // If the color source has an intrinsic size, then we use that to
-    // create the src contents as a simplification. Otherwise we use
-    // the extent of the texture coordinates to determine how large
-    // the src contents should be. If neither has a value we fall back
-    // to using the geometry coverage data.
-    Rect src_coverage;
-    auto size = src_contents->GetColorSourceSize();
-    if (size.has_value()) {
-      src_coverage = Rect::MakeXYWH(0, 0, size->width, size->height);
-    } else {
-      auto cvg = vertices->GetCoverage(Matrix{});
-      FML_CHECK(cvg.has_value());
-      src_coverage =
-          // Covered by FML_CHECK.
-          // NOLINTNEXTLINE(bugprone-unchecked-optional-access)
-          vertices->GetTextureCoordinateCoverge().value_or(cvg.value());
-    }
-    src_contents =
-        src_paint.CreateContentsForGeometry(Geometry::MakeRect(src_coverage));
+
+  // If the color source has an intrinsic size, then we use that to
+  // create the src contents as a simplification. Otherwise we use
+  // the extent of the texture coordinates to determine how large
+  // the src contents should be. If neither has a value we fall back
+  // to using the geometry coverage data.
+  Rect src_coverage;
+  auto size = src_contents->GetColorSourceSize();
+  if (size.has_value()) {
+    src_coverage = Rect::MakeXYWH(0, 0, size->width, size->height);
+  } else {
+    auto cvg = vertices->GetCoverage(Matrix{});
+    FML_CHECK(cvg.has_value());
+    src_coverage =
+        // Covered by FML_CHECK.
+        // NOLINTNEXTLINE(bugprone-unchecked-optional-access)
+        vertices->GetTextureCoordinateCoverge().value_or(cvg.value());
   }
+  src_contents =
+      src_paint.CreateContentsForGeometry(Geometry::MakeRect(src_coverage));
 
-  auto contents = std::make_shared<VerticesContents>();
-  contents->SetAlpha(paint.color.alpha);
+  auto contents = std::make_shared<VerticesSimpleBlendContents>();
   contents->SetBlendMode(blend_mode);
+  contents->SetAlpha(paint.color.alpha);
   contents->SetGeometry(vertices);
-  contents->SetSourceContents(std::move(src_contents));
+  contents->SetLazyTexture([src_contents](const ContentContext& renderer) {
+    return src_contents->RenderToSnapshot(renderer, {})->texture;
+  });
   entity.SetContents(paint.WithFilters(std::move(contents)));
-
   AddRenderEntityToCurrentPass(std::move(entity));
 }
 

impeller/entity/BUILD.gn

@@ -262,7 +262,6 @@ impeller_component("entity_unittests") {
     "contents/filters/inputs/filter_input_unittests.cc",
     "contents/host_buffer_unittests.cc",
     "contents/tiled_texture_contents_unittests.cc",
-    "contents/vertices_contents_unittests.cc",
     "entity_pass_target_unittests.cc",
     "entity_pass_unittests.cc",
     "entity_playground.cc",

impeller/entity/contents/content_context.cc

@@ -11,6 +11,7 @@
 #include "impeller/base/strings.h"
 #include "impeller/base/validation.h"
 #include "impeller/core/formats.h"
+#include "impeller/core/texture_descriptor.h"
 #include "impeller/entity/contents/framebuffer_blend_contents.h"
 #include "impeller/entity/entity.h"
 #include "impeller/entity/render_target_cache.h"
@@ -255,6 +256,18 @@ ContentContext::ContentContext(
     return;
   }
 
+  {
+    TextureDescriptor desc;
+    desc.storage_mode = StorageMode::kHostVisible;
+    desc.format = PixelFormat::kR8G8B8A8UNormInt;
+    desc.size = ISize{1, 1};
+    empty_texture_ = GetContext()->GetResourceAllocator()->CreateTexture(desc);
+    auto data = Color::BlackTransparent().ToR8G8B8A8();
+    if (!empty_texture_->SetContents(data.data(), 4)) {
+      VALIDATION_LOG << "Failed to create empty texture.";
+    }
+  }
+
   auto options = ContentContextOptions{
       .sample_count = SampleCount::kCount4,
       .color_attachment_pixel_format =
@@ -448,6 +461,10 @@ bool ContentContext::IsValid() const {
   return is_valid_;
 }
 
+std::shared_ptr<Texture> ContentContext::GetEmptyTexture() const {
+  return empty_texture_;
+}
+
 fml::StatusOr<RenderTarget> ContentContext::MakeSubpass(
     std::string_view label,
     ISize texture_size,
@@ -567,22 +584,6 @@ void ContentContext::ClearCachedRuntimeEffectPipeline(
 void ContentContext::InitializeCommonlyUsedShadersIfNeeded() const {
   TRACE_EVENT0("flutter", "InitializeCommonlyUsedShadersIfNeeded");
   GetContext()->InitializeCommonlyUsedShadersIfNeeded();
-
-  // On ARM devices, the initial usage of vkCmdCopyBufferToImage has been
-  // observed to take 10s of ms as an internal shader is compiled to perform
-  // the operation. Similarly, the initial render pass can also take 10s of ms
-  // for a similar reason. Because the context object is initialized far
-  // before the first frame, create a trivial texture and render pass to force
-  // the driver to compiler these shaders before the frame begins.
-  TextureDescriptor desc;
-  desc.size = {1, 1};
-  desc.storage_mode = StorageMode::kHostVisible;
-  desc.format = PixelFormat::kR8G8B8A8UNormInt;
-  auto texture = GetContext()->GetResourceAllocator()->CreateTexture(desc);
-  uint32_t color = 0;
-  if (!texture->SetContents(reinterpret_cast<uint8_t*>(&color), 4u)) {
-    VALIDATION_LOG << "Failed to set bootstrap texture.";
-  }
 }
 
 }  // namespace impeller

impeller/entity/contents/content_context.h

@@ -714,6 +714,10 @@ class ContentContext {
     return GetPipeline(vertices_uber_shader_, opts);
   }
 
+  // An empty 1x1 texture for binding drawVertices/drawAtlas or other cases
+  // that don't always have a texture (due to blending).
+  std::shared_ptr<Texture> GetEmptyTexture() const;
+
   std::shared_ptr<Context> GetContext() const;
 
   const Capabilities& GetDeviceCapabilities() const;
@@ -1034,6 +1038,7 @@ class ContentContext {
 #endif  // IMPELLER_ENABLE_3D
   std::shared_ptr<RenderTargetAllocator> render_target_cache_;
   std::shared_ptr<HostBuffer> host_buffer_;
+  std::shared_ptr<Texture> empty_texture_;
   bool wireframe_ = false;
 
   ContentContext(const ContentContext&) = delete;