[Impeller Scene] Depth attachment; baked lighting example

impeller/fixtures/BUILD.gn

@@ -59,6 +59,7 @@ test_fixtures("file_fixtures") {
     "boston.jpg",
     "embarcadero.jpg",
     "flutter_logo.glb",
+    "flutter_logo_baked.png",
     "kalimba.jpg",
     "multiple_stages.hlsl",
     "resources_limit.vert",

impeller/playground/backend/gles/playground_impl_gles.cc

@@ -68,7 +68,7 @@ PlaygroundImplGLES::PlaygroundImplGLES()
   ::glfwWindowHint(GLFW_GREEN_BITS, 8);
   ::glfwWindowHint(GLFW_BLUE_BITS, 8);
   ::glfwWindowHint(GLFW_ALPHA_BITS, 8);
-  ::glfwWindowHint(GLFW_DEPTH_BITS, 0);    // no depth buffer
+  ::glfwWindowHint(GLFW_DEPTH_BITS, 32);   // 32 bit depth buffer
   ::glfwWindowHint(GLFW_STENCIL_BITS, 8);  // 8 bit stencil buffer
   ::glfwWindowHint(GLFW_SAMPLES, 4);       // 4xMSAA
 

impeller/playground/playground.cc

@@ -263,35 +263,8 @@ bool Playground::OpenPlaygroundHere(
         }
         render_target.SetColorAttachment(color0, 0);
 
-#ifndef IMPELLER_ENABLE_VULKAN
-        {
-          TextureDescriptor stencil0_tex;
-          stencil0_tex.storage_mode = StorageMode::kDeviceTransient;
-          stencil0_tex.type = TextureType::kTexture2D;
-          stencil0_tex.sample_count = SampleCount::kCount1;
-          stencil0_tex.format = PixelFormat::kDefaultStencil;
-          stencil0_tex.size = color0.texture->GetSize();
-          stencil0_tex.usage =
-              static_cast<TextureUsageMask>(TextureUsage::kRenderTarget);
-          auto stencil_texture =
-              renderer->GetContext()->GetResourceAllocator()->CreateTexture(
-                  stencil0_tex);
-
-          if (!stencil_texture) {
-            VALIDATION_LOG << "Could not create stencil texture.";
-            return false;
-          }
-          stencil_texture->SetLabel("ImguiStencil");
-
-          StencilAttachment stencil0;
-          stencil0.texture = stencil_texture;
-          stencil0.clear_stencil = 0;
-          stencil0.load_action = LoadAction::kClear;
-          stencil0.store_action = StoreAction::kDontCare;
-
-          render_target.SetStencilAttachment(stencil0);
-        }
-#endif
+        render_target.SetStencilAttachment(std::nullopt);
+        render_target.SetDepthAttachment(std::nullopt);
 
         auto pass = buffer->CreateRenderPass(render_target);
         if (!pass) {

impeller/renderer/backend/gles/texture_gles.cc

@@ -109,6 +109,7 @@ struct TexImage2DData {
         break;
       case PixelFormat::kUnknown:
       case PixelFormat::kS8UInt:
+      case PixelFormat::kD32FloatS8UInt:
       case PixelFormat::kR8UNormInt:
       case PixelFormat::kR8G8UNormInt:
         return;
@@ -136,15 +137,11 @@ struct TexImage2DData {
         break;
       }
       case PixelFormat::kR8G8B8A8UNormIntSRGB:
-        return;
       case PixelFormat::kB8G8R8A8UNormInt:
-        return;
       case PixelFormat::kB8G8R8A8UNormIntSRGB:
-        return;
       case PixelFormat::kS8UInt:
-        return;
+      case PixelFormat::kD32FloatS8UInt:
       case PixelFormat::kR8UNormInt:
-        return;
       case PixelFormat::kR8G8UNormInt:
         return;
     }
@@ -279,6 +276,8 @@ static std::optional<GLenum> ToRenderBufferFormat(PixelFormat format) {
       return GL_RGBA4;
     case PixelFormat::kS8UInt:
       return GL_STENCIL_INDEX8;
+    case PixelFormat::kD32FloatS8UInt:
+      return GL_DEPTH32F_STENCIL8;
     case PixelFormat::kUnknown:
     case PixelFormat::kA8UNormInt:
     case PixelFormat::kR8UNormInt:

impeller/renderer/backend/metal/formats_mtl.h

@@ -27,10 +27,12 @@ constexpr PixelFormat FromMTLPixelFormat(MTLPixelFormat format) {
       return PixelFormat::kB8G8R8A8UNormIntSRGB;
     case MTLPixelFormatRGBA8Unorm:
       return PixelFormat::kR8G8B8A8UNormInt;
-    case MTLPixelFormatStencil8:
-      return PixelFormat::kS8UInt;
     case MTLPixelFormatRGBA8Unorm_sRGB:
       return PixelFormat::kR8G8B8A8UNormIntSRGB;
+    case MTLPixelFormatStencil8:
+      return PixelFormat::kS8UInt;
+    case MTLPixelFormatDepth32Float_Stencil8:
+      return PixelFormat::kD32FloatS8UInt;
     default:
       return PixelFormat::kUnknown;
   }
@@ -53,10 +55,12 @@ constexpr MTLPixelFormat ToMTLPixelFormat(PixelFormat format) {
       return MTLPixelFormatBGRA8Unorm_sRGB;
     case PixelFormat::kR8G8B8A8UNormInt:
       return MTLPixelFormatRGBA8Unorm;
-    case PixelFormat::kS8UInt:
-      return MTLPixelFormatStencil8;
     case PixelFormat::kR8G8B8A8UNormIntSRGB:
       return MTLPixelFormatRGBA8Unorm_sRGB;
+    case PixelFormat::kS8UInt:
+      return MTLPixelFormatStencil8;
+    case PixelFormat::kD32FloatS8UInt:
+      return MTLPixelFormatDepth32Float_Stencil8;
   }
   return MTLPixelFormatInvalid;
 };

impeller/renderer/backend/vulkan/formats_vk.h

@@ -150,6 +150,8 @@ constexpr vk::Format ToVKImageFormat(PixelFormat format) {
       return vk::Format::eB8G8R8A8Srgb;
     case PixelFormat::kS8UInt:
       return vk::Format::eS8Uint;
+    case PixelFormat::kD32FloatS8UInt:
+      return vk::Format::eD32SfloatS8Uint;
     case PixelFormat::kR8UNormInt:
       return vk::Format::eR8Unorm;
     case PixelFormat::kR8G8UNormInt:
@@ -179,6 +181,9 @@ constexpr PixelFormat ToPixelFormat(vk::Format format) {
     case vk::Format::eS8Uint:
       return PixelFormat::kS8UInt;
 
+    case vk::Format::eD32SfloatS8Uint:
+      return PixelFormat::kD32FloatS8UInt;
+
     case vk::Format::eR8Unorm:
       return PixelFormat::kR8UNormInt;
 

impeller/renderer/formats.h

@@ -87,7 +87,10 @@ enum class PixelFormat {
   kR8G8B8A8UNormIntSRGB,
   kB8G8R8A8UNormInt,
   kB8G8R8A8UNormIntSRGB,
+
+  // Depth and stencil formats.
   kS8UInt,
+  kD32FloatS8UInt,
 
   // Defaults. If you don't know which ones to use, these are usually a safe
   // bet.
@@ -285,6 +288,8 @@ constexpr size_t BytesPerPixelForPixelFormat(PixelFormat format) {
     case PixelFormat::kB8G8R8A8UNormInt:
     case PixelFormat::kB8G8R8A8UNormIntSRGB:
       return 4u;
+    case PixelFormat::kD32FloatS8UInt:
+      return 5u;
   }
   return 0u;
 }

impeller/renderer/render_target.cc

@@ -149,15 +149,21 @@ RenderTarget& RenderTarget::SetColorAttachment(
   return *this;
 }
 
-RenderTarget& RenderTarget::SetDepthAttachment(DepthAttachment attachment) {
-  if (attachment.IsValid()) {
+RenderTarget& RenderTarget::SetDepthAttachment(
+    std::optional<DepthAttachment> attachment) {
+  if (!attachment.has_value()) {
+    depth_ = std::nullopt;
+  } else if (attachment->IsValid()) {
     depth_ = std::move(attachment);
   }
   return *this;
 }
 
-RenderTarget& RenderTarget::SetStencilAttachment(StencilAttachment attachment) {
-  if (attachment.IsValid()) {
+RenderTarget& RenderTarget::SetStencilAttachment(
+    std::optional<StencilAttachment> attachment) {
+  if (!attachment.has_value()) {
+    stencil_ = std::nullopt;
+  } else if (attachment->IsValid()) {
     stencil_ = std::move(attachment);
   }
   return *this;

impeller/renderer/render_target.h

@@ -61,9 +61,10 @@ class RenderTarget {
   RenderTarget& SetColorAttachment(const ColorAttachment& attachment,
                                    size_t index);
 
-  RenderTarget& SetDepthAttachment(DepthAttachment attachment);
+  RenderTarget& SetDepthAttachment(std::optional<DepthAttachment> attachment);
 
-  RenderTarget& SetStencilAttachment(StencilAttachment attachment);
+  RenderTarget& SetStencilAttachment(
+      std::optional<StencilAttachment> attachment);
 
   const std::map<size_t, ColorAttachment>& GetColorAttachments() const;
 

impeller/scene/material.cc

@@ -55,6 +55,10 @@ void UnlitMaterial::SetColorTexture(std::shared_ptr<Texture> color_texture) {
   color_texture_ = std::move(color_texture);
 }
 
+void UnlitMaterial::SetVertexColorWeight(Scalar weight) {
+  vertex_color_weight_ = weight;
+}
+
 // |Material|
 std::shared_ptr<Pipeline<PipelineDescriptor>> UnlitMaterial::GetPipeline(
     const SceneContext& scene_context,
@@ -69,6 +73,7 @@ void UnlitMaterial::BindToCommand(const SceneContext& scene_context,
   // Uniform buffer.
   UnlitPipeline::FragmentShader::FragInfo info;
   info.color = color_;
+  info.vertex_color_weight = vertex_color_weight_;
   UnlitPipeline::FragmentShader::BindFragInfo(command,
                                               buffer.EmplaceUniform(info));
 

impeller/scene/material.h

@@ -66,6 +66,8 @@ class UnlitMaterial final : public Material {
 
   void SetColorTexture(std::shared_ptr<Texture> color_texture);
 
+  void SetVertexColorWeight(Scalar weight);
+
   // |Material|
   std::shared_ptr<Pipeline<PipelineDescriptor>> GetPipeline(
       const SceneContext& scene_context,
@@ -79,6 +81,7 @@ class UnlitMaterial final : public Material {
  private:
   Color color_ = Color::White();
   std::shared_ptr<Texture> color_texture_;
+  Scalar vertex_color_weight_ = 1;
 };
 
 class StandardMaterial final : public Material {

impeller/scene/scene_context.cc

@@ -10,6 +10,18 @@ namespace scene {
 
 void SceneContextOptions::ApplyToPipelineDescriptor(
     PipelineDescriptor& desc) const {
+  DepthAttachmentDescriptor depth;
+  depth.depth_compare = CompareFunction::kLess;
+  depth.depth_write_enabled = true;
+  desc.SetDepthStencilAttachmentDescriptor(depth);
+  desc.SetDepthPixelFormat(PixelFormat::kD32FloatS8UInt);
+
+  StencilAttachmentDescriptor stencil;
+  stencil.stencil_compare = CompareFunction::kAlways;
+  stencil.depth_stencil_pass = StencilOperation::kKeep;
+  desc.SetStencilAttachmentDescriptors(stencil);
+  desc.SetStencilPixelFormat(PixelFormat::kD32FloatS8UInt);
+
   desc.SetSampleCount(sample_count);
   desc.SetPrimitiveType(primitive_type);
 }

impeller/scene/scene_encoder.cc

@@ -49,7 +49,37 @@ static void EncodeCommand(const SceneContext& scene_context,
 std::shared_ptr<CommandBuffer> SceneEncoder::BuildSceneCommandBuffer(
     const SceneContext& scene_context,
     const Camera& camera,
-    const RenderTarget& render_target) const {
+    RenderTarget render_target) const {
+  {
+    TextureDescriptor ds_texture;
+    ds_texture.type = TextureType::kTexture2DMultisample;
+    ds_texture.format = PixelFormat::kD32FloatS8UInt;
+    ds_texture.size = render_target.GetRenderTargetSize();
+    ds_texture.usage =
+        static_cast<TextureUsageMask>(TextureUsage::kRenderTarget);
+    ds_texture.sample_count = SampleCount::kCount4;
+    ds_texture.storage_mode = StorageMode::kDeviceTransient;
+    auto texture =
+        scene_context.GetContext()->GetResourceAllocator()->CreateTexture(
+            ds_texture);
+
+    DepthAttachment depth;
+    depth.load_action = LoadAction::kClear;
+    depth.store_action = StoreAction::kDontCare;
+    depth.clear_depth = 1.0;
+    depth.texture = texture;
+    render_target.SetDepthAttachment(depth);
+
+    // The stencil and depth buffers must be the same texture for MacOS ARM
+    // and Vulkan.
+    StencilAttachment stencil;
+    stencil.load_action = LoadAction::kClear;
+    stencil.store_action = StoreAction::kDontCare;
+    stencil.clear_stencil = 0u;
+    stencil.texture = texture;
+    render_target.SetStencilAttachment(stencil);
+  }
+
   auto command_buffer = scene_context.GetContext()->CreateCommandBuffer();
   if (!command_buffer) {
     FML_LOG(ERROR) << "Failed to create command buffer.";

impeller/scene/scene_encoder.h

@@ -36,7 +36,7 @@ class SceneEncoder {
   std::shared_ptr<CommandBuffer> BuildSceneCommandBuffer(
       const SceneContext& scene_context,
       const Camera& camera,
-      const RenderTarget& render_target) const;
+      RenderTarget render_target) const;
 
   std::vector<SceneCommand> commands_;
 

impeller/scene/scene_unittests.cc

@@ -2,13 +2,18 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+#include <cmath>
+#include <memory>
+
 #include "flutter/testing/testing.h"
 #include "impeller/geometry/color.h"
 #include "impeller/geometry/constants.h"
 #include "impeller/geometry/matrix.h"
+#include "impeller/geometry/quaternion.h"
 #include "impeller/geometry/vector.h"
 #include "impeller/playground/playground.h"
 #include "impeller/playground/playground_test.h"
+#include "impeller/renderer/formats.h"
 #include "impeller/scene/camera.h"
 #include "impeller/scene/geometry.h"
 #include "impeller/scene/importer/scene_flatbuffers.h"
@@ -80,18 +85,27 @@ TEST_P(SceneTest, GLTFScene) {
   auto geometry = Geometry::MakeFromFBMesh(*fb_mesh, *allocator);
   ASSERT_NE(geometry, nullptr);
 
+  std::shared_ptr<UnlitMaterial> material = Material::MakeUnlit();
+  auto bridge = CreateTextureForFixture("flutter_logo_baked.png");
+  material->SetColorTexture(bridge);
+  material->SetVertexColorWeight(0);
+
   Renderer::RenderCallback callback = [&](RenderTarget& render_target) {
     auto scene = Scene(GetContext());
 
     auto mesh = SceneEntity::MakeStaticMesh();
-    mesh->SetMaterial(Material::MakeUnlit());
+    mesh->SetMaterial(material);
     mesh->SetGeometry(geometry);
+    mesh->SetLocalTransform(Matrix::MakeScale({3, 3, 3}));
     scene.Add(mesh);
 
+    Quaternion rotation({0, 1, 0}, -GetSecondsElapsed() * 0.5);
+    Vector3 start_position(-1, -1.5, -5);
+
     // Face towards the +Z direction (+X right, +Y up).
     auto camera = Camera::MakePerspective(
-                      /* fov */ Radians(kPiOver4),
-                      /* position */ {2, 2, -5})
+                      /* fov */ Degrees(60),
+                      /* position */ rotation * start_position)
                       .LookAt(
                           /* target */ Vector3(),
                           /* up */ {0, 1, 0});

impeller/scene/shaders/unlit.frag

@@ -4,6 +4,7 @@
 
 uniform FragInfo {
   vec4 color;
+  float vertex_color_weight;
 }
 frag_info;
 
@@ -17,6 +18,7 @@ in vec4 v_color;
 out vec4 frag_color;
 
 void main() {
-  frag_color =
-      texture(base_color_texture, v_texture_coords) * v_color * frag_info.color;
+  vec4 vertex_color = mix(vec4(1), v_color, frag_info.vertex_color_weight);
+  frag_color = texture(base_color_texture, v_texture_coords) * vertex_color *
+               frag_info.color;
 }