Make sure texture bindings are correctly propagated.

engine/src/flutter/impeller/compiler/code_gen_template.h

@@ -80,15 +80,10 @@ struct {{camel_case(shader_name)}}{{camel_case(shader_stage)}}Shader {
   // ===========================================================================
 {% for sampled_image in sampled_images %}
 
-  static constexpr auto kInput{{camel_case(sampled_image.name)}} = ShaderStageIOSlot { // {{sampled_image.name}}
-    "{{sampled_image.name}}",             // name
-    {{sampled_image.location}}u,          // attribute location
-    {{sampled_image.descriptor_set}}u,    // attribute set
-    {{sampled_image.binding}}u,           // attribute binding
-    {{sampled_image.type.type_name}},     // type
-    {{sampled_image.type.bit_width}}u,    // bit width of type
-    {{sampled_image.type.vec_size}}u,     // vec size
-    {{sampled_image.type.columns}}u       // number of columns
+  static constexpr auto kSampledImage{{camel_case(sampled_image.name)}} = SampledImageSlot { // {{sampled_image.name}}
+    "{{sampled_image.name}}",      // name
+    {{sampled_image.msl_res_0}}u,  // auto primary
+    {{sampled_image.msl_res_1}}u,  // auto secondary
   };
 {% endfor %}
 {% endif %}

engine/src/flutter/impeller/compiler/reflector.cc

@@ -284,6 +284,14 @@ std::optional<nlohmann::json::object_t> Reflector::ReflectResource(
       resource.id, spv::Decoration::DecorationLocation);
   result["index"] =
       compiler_->get_decoration(resource.id, spv::Decoration::DecorationIndex);
+  result["msl_res_0"] =
+      compiler_->get_automatic_msl_resource_binding(resource.id);
+  result["msl_res_1"] =
+      compiler_->get_automatic_msl_resource_binding_secondary(resource.id);
+  result["msl_res_2"] =
+      compiler_->get_automatic_msl_resource_binding_tertiary(resource.id);
+  result["msl_res_3"] =
+      compiler_->get_automatic_msl_resource_binding_quaternary(resource.id);
   auto type = ReflectType(resource.type_id);
   if (!type.has_value()) {
     return std::nullopt;

engine/src/flutter/impeller/playground/playground.h

@@ -6,6 +6,7 @@
 #include "flutter/fml/macros.h"
 #include "gtest/gtest.h"
 #include "impeller/compositor/renderer.h"
+#include "impeller/compositor/texture.h"
 
 namespace impeller {
 
@@ -19,6 +20,9 @@ class Playground : public ::testing::Test {
 
   bool OpenPlaygroundHere(Renderer::RenderCallback render_callback);
 
+  std::shared_ptr<Texture> CreateTextureForFixture(
+      const char* fixture_name) const;
+
  private:
   Renderer renderer_;
 

engine/src/flutter/impeller/playground/playground.mm

@@ -6,11 +6,13 @@
 
 #include "flutter/fml/paths.h"
 #include "flutter/testing/testing.h"
+#include "impeller/compositor/allocator.h"
 #include "impeller/compositor/context.h"
 #include "impeller/compositor/formats_metal.h"
 #include "impeller/compositor/render_pass.h"
 #include "impeller/compositor/renderer.h"
 #include "impeller/compositor/surface.h"
+#include "impeller/image/compressed_image.h"
 #include "impeller/playground/playground.h"
 
 #define GLFW_INCLUDE_NONE
@@ -144,4 +146,37 @@ bool Playground::OpenPlaygroundHere(Renderer::RenderCallback render_callback) {
   return true;
 }
 
+std::shared_ptr<Texture> Playground::CreateTextureForFixture(
+    const char* fixture_name) const {
+  CompressedImage compressed_image(
+      flutter::testing::OpenFixtureAsMapping(fixture_name));
+  auto image = compressed_image.Decode().ConvertToRGBA();
+  if (!image.IsValid()) {
+    FML_LOG(ERROR) << "Could not find fixture named " << fixture_name;
+    return nullptr;
+  }
+  auto texture_descriptor = TextureDescriptor::MakeFromImageResult(image);
+  if (!texture_descriptor.has_value()) {
+    FML_LOG(ERROR) << "Could not figure out texture descriptor for fixture "
+                   << fixture_name;
+    return nullptr;
+  }
+  auto texture =
+      renderer_.GetContext()->GetPermanentsAllocator()->CreateTexture(
+          StorageMode::kHostVisible, texture_descriptor.value());
+  if (!texture) {
+    FML_LOG(ERROR) << "Could not allocate texture for fixture " << fixture_name;
+    return nullptr;
+  }
+  texture->SetLabel(fixture_name);
+  auto uploaded = texture->SetContents(image.GetAllocation()->GetMapping(),
+                                       image.GetAllocation()->GetSize());
+  if (!uploaded) {
+    FML_LOG(ERROR) << "Could not upload texture to device memory for fixture "
+                   << fixture_name;
+    return nullptr;
+  }
+  return texture;
+}
+
 }  // namespace impeller

engine/src/flutter/impeller/primitives/box.frag

@@ -2,13 +2,20 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+uniform FrameInfo {
+  float current_time;
+} frame;
+
 in vec4 color;
 in vec2 interporlated_texture_coordinates;
 
 out vec4 frag_color;
 
-uniform sampler2D contents_texture;
+uniform sampler2D contents1_texture;
+uniform sampler2D contents2_texture;
 
 void main() {
-  frag_color = texture(contents_texture, interporlated_texture_coordinates);
+  vec4 tex1 = texture(contents1_texture, interporlated_texture_coordinates);
+  vec4 tex2 = texture(contents2_texture, interporlated_texture_coordinates);
+  frag_color = mix(tex1, tex2, frame.current_time - floor(frame.current_time));
 }

engine/src/flutter/impeller/primitives/primitives_unittests.mm

@@ -47,20 +47,9 @@ TEST_F(PrimitivesTest, CanCreateBoxPrimitive) {
       vertex_builder.CreateVertexBuffer(*context->GetPermanentsAllocator());
   ASSERT_TRUE(vertex_buffer);
 
-  // Contents texture.
-  CompressedImage compressed_image(
-      flutter::testing::OpenFixtureAsMapping("bay_bridge.jpg"));
-  auto image = compressed_image.Decode().ConvertToRGBA();
-  ASSERT_TRUE(image.IsValid());
-  auto texture_descriptor = TextureDescriptor::MakeFromImageResult(image);
-  ASSERT_TRUE(texture_descriptor.has_value());
-  auto texture = context->GetPermanentsAllocator()->CreateTexture(
-      StorageMode::kHostVisible, texture_descriptor.value());
-  ASSERT_TRUE(texture);
-  texture->SetLabel("Bay Bridge");
-  auto uploaded = texture->SetContents(image.GetAllocation()->GetMapping(),
-                                       image.GetAllocation()->GetSize());
-  ASSERT_TRUE(uploaded);
+  auto bridge = CreateTextureForFixture("bay_bridge.jpg");
+  auto boston = CreateTextureForFixture("boston.jpg");
+  ASSERT_TRUE(bridge && boston);
   auto sampler = context->GetSamplerLibrary()->GetSampler({});
   ASSERT_TRUE(sampler);
   Renderer::RenderCallback callback = [&](const Surface& surface,
@@ -78,10 +67,23 @@ TEST_F(PrimitivesTest, CanCreateBoxPrimitive) {
         .buffers[BoxVertexShader::kUniformUniformBuffer.binding] =
         pass.GetTransientsBuffer().EmplaceUniform(uniforms);
 
+    BoxFragmentShader::FrameInfo frame_info;
+    frame_info.current_time = fml::TimePoint::Now().ToEpochDelta().ToSecondsF();
     cmd.fragment_bindings
-        .textures[BoxFragmentShader::kInputContentsTexture.location] = texture;
+        .buffers[BoxFragmentShader::kUniformFrameInfo.binding] =
+        pass.GetTransientsBuffer().EmplaceUniform(frame_info);
     cmd.fragment_bindings
-        .samplers[BoxFragmentShader::kInputContentsTexture.location] = sampler;
+        .textures[BoxFragmentShader::kSampledImageContents1Texture
+                      .texture_index] = bridge;
+    cmd.fragment_bindings
+        .samplers[BoxFragmentShader::kSampledImageContents1Texture
+                      .sampler_index] = sampler;
+    cmd.fragment_bindings
+        .textures[BoxFragmentShader::kSampledImageContents2Texture
+                      .texture_index] = boston;
+    cmd.fragment_bindings
+        .samplers[BoxFragmentShader::kSampledImageContents2Texture
+                      .sampler_index] = sampler;
 
     cmd.index_buffer = vertex_buffer.index_buffer;
     cmd.index_count = vertex_buffer.index_count;

engine/src/flutter/impeller/shader_glue/shader_types.h

@@ -58,6 +58,16 @@ struct ShaderStageIOSlot {
   size_t columns;
 };
 
+struct SampledImageSlot {
+  const char* name;
+  size_t texture_index;
+  size_t sampler_index;
+
+  constexpr bool HasTexture() const { return texture_index < 32u; }
+
+  constexpr bool HasSampler() const { return sampler_index < 32u; }
+};
+
 template <size_t Size>
 struct Padding {
  private: