text: // Copyright 2019 The Dawn Authors
  //
  // Licensed under the Apache License, Version 2.0 (the "License");
  // you may not use this file except in compliance with the License.
  // You may obtain a copy of the License at
  //
  //     http://www.apache.org/licenses/LICENSE-2.0
  //
  // Unless required by applicable law or agreed to in writing, software
  // distributed under the License is distributed on an "AS IS" BASIS,
  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  // See the License for the specific language governing permissions and
  // limitations under the License.
  
  #include "dawn/tests/DawnTest.h"
  
  #include "dawn/utils/ComboRenderPipelineDescriptor.h"
  #include "dawn/utils/WGPUHelpers.h"
  
  constexpr uint32_t kRTSize = 16;
  constexpr wgpu::TextureFormat kFormat = wgpu::TextureFormat::RGBA8Unorm;
  
  class RenderPassTest : public DawnTest {
    protected:
      void SetUp() override {
          DawnTest::SetUp();
  
          // Shaders to draw a bottom-left triangle in blue.
          mVSModule = utils::CreateShaderModule(device, R"(
              @stage(vertex)
              fn main(@builtin(vertex_index) VertexIndex : u32) -> @builtin(position) vec4<f32> {
                  var pos = array<vec2<f32>, 3>(
                      vec2<f32>(-1.0,  1.0),
                      vec2<f32>( 1.0, -1.0),
                      vec2<f32>(-1.0, -1.0));
  
                  return vec4<f32>(pos[VertexIndex], 0.0, 1.0);
              })");
  
          wgpu::ShaderModule fsModule = utils::CreateShaderModule(device, R"(
              @stage(fragment) fn main() -> @location(0) vec4<f32> {
                  return vec4<f32>(0.0, 0.0, 1.0, 1.0);
              })");
  
          utils::ComboRenderPipelineDescriptor descriptor;
          descriptor.vertex.module = mVSModule;
          descriptor.cFragment.module = fsModule;
          descriptor.primitive.topology = wgpu::PrimitiveTopology::TriangleList;
          descriptor.cTargets[0].format = kFormat;
  
          pipeline = device.CreateRenderPipeline(&descriptor);
      }
  
      wgpu::Texture CreateDefault2DTexture() {
          wgpu::TextureDescriptor descriptor;
          descriptor.dimension = wgpu::TextureDimension::e2D;
          descriptor.size.width = kRTSize;
          descriptor.size.height = kRTSize;
          descriptor.size.depthOrArrayLayers = 1;
          descriptor.sampleCount = 1;
          descriptor.format = kFormat;
          descriptor.mipLevelCount = 1;
          descriptor.usage = wgpu::TextureUsage::RenderAttachment | wgpu::TextureUsage::CopySrc;
          return device.CreateTexture(&descriptor);
      }
  
      wgpu::ShaderModule mVSModule;
      wgpu::RenderPipeline pipeline;
  };
  
  // Test using two different render passes in one commandBuffer works correctly.
  TEST_P(RenderPassTest, TwoRenderPassesInOneCommandBuffer) {
      if (IsOpenGL() || IsMetal()) {
          // crbug.com/950768
          // This test is consistently failing on OpenGL and flaky on Metal.
          return;
      }
  
      wgpu::Texture renderTarget1 = CreateDefault2DTexture();
      wgpu::Texture renderTarget2 = CreateDefault2DTexture();
      wgpu::CommandEncoder encoder = device.CreateCommandEncoder();
  
      {
          // In the first render pass we clear renderTarget1 to red and draw a blue triangle in the
          // bottom left of renderTarget1.
          utils::ComboRenderPassDescriptor renderPass({renderTarget1.CreateView()});
          renderPass.cColorAttachments[0].clearColor = {1.0f, 0.0f, 0.0f, 1.0f};
  
          wgpu::RenderPassEncoder pass = encoder.BeginRenderPass(&renderPass);
          pass.SetPipeline(pipeline);
          pass.Draw(3);
          pass.End();
      }
  
      {
          // In the second render pass we clear renderTarget2 to green and draw a blue triangle in the
          // bottom left of renderTarget2.
          utils::ComboRenderPassDescriptor renderPass({renderTarget2.CreateView()});
          renderPass.cColorAttachments[0].clearColor = {0.0f, 1.0f, 0.0f, 1.0f};
  
          wgpu::RenderPassEncoder pass = encoder.BeginRenderPass(&renderPass);
          pass.SetPipeline(pipeline);
          pass.Draw(3);
          pass.End();
      }
  
      wgpu::CommandBuffer commands = encoder.Finish();
      queue.Submit(1, &commands);
  
      EXPECT_PIXEL_RGBA8_EQ(RGBA8::kBlue, renderTarget1, 1, kRTSize - 1);
      EXPECT_PIXEL_RGBA8_EQ(RGBA8::kRed, renderTarget1, kRTSize - 1, 1);
  
      EXPECT_PIXEL_RGBA8_EQ(RGBA8::kBlue, renderTarget2, 1, kRTSize - 1);
      EXPECT_PIXEL_RGBA8_EQ(RGBA8::kGreen, renderTarget2, kRTSize - 1, 1);
  }
  
  // Verify that the content in the color attachment will not be changed if there is no corresponding
  // fragment shader outputs in the render pipeline, the load operation is LoadOp::Load and the store
  // operation is StoreOp::Store.
  TEST_P(RenderPassTest, NoCorrespondingFragmentShaderOutputs) {
      wgpu::Texture renderTarget = CreateDefault2DTexture();
      wgpu::CommandEncoder encoder = device.CreateCommandEncoder();
  
      wgpu::TextureView renderTargetView = renderTarget.CreateView();
  
      utils::ComboRenderPassDescriptor renderPass({renderTargetView});
      renderPass.cColorAttachments[0].clearColor = {1.0f, 0.0f, 0.0f, 1.0f};
      renderPass.cColorAttachments[0].loadOp = wgpu::LoadOp::Clear;
      renderPass.cColorAttachments[0].storeOp = wgpu::StoreOp::Store;
      wgpu::RenderPassEncoder pass = encoder.BeginRenderPass(&renderPass);
  
      {
          // First we draw a blue triangle in the bottom left of renderTarget.
          pass.SetPipeline(pipeline);
          pass.Draw(3);
      }
  
      {
          // Next we use a pipeline whose fragment shader has no outputs.
          wgpu::ShaderModule fsModule = utils::CreateShaderModule(device, R"(
              @stage(fragment) fn main() {
              })");
          utils::ComboRenderPipelineDescriptor descriptor;
          descriptor.vertex.module = mVSModule;
          descriptor.cFragment.module = fsModule;
          descriptor.primitive.topology = wgpu::PrimitiveTopology::TriangleList;
          descriptor.cTargets[0].format = kFormat;
          descriptor.cTargets[0].writeMask = wgpu::ColorWriteMask::None;
  
          wgpu::RenderPipeline pipelineWithNoFragmentOutput =
              device.CreateRenderPipeline(&descriptor);
  
          pass.SetPipeline(pipelineWithNoFragmentOutput);
          pass.Draw(3);
      }
  
      pass.End();
  
      wgpu::CommandBuffer commands = encoder.Finish();
      queue.Submit(1, &commands);
  
      EXPECT_PIXEL_RGBA8_EQ(RGBA8::kBlue, renderTarget, 2, kRTSize - 1);
      EXPECT_PIXEL_RGBA8_EQ(RGBA8::kRed, renderTarget, kRTSize - 1, 1);
  }
  
  DAWN_INSTANTIATE_TEST(RenderPassTest,
                        D3D12Backend(),
                        D3D12Backend({}, {"use_d3d12_render_pass"}),
                        MetalBackend(),
                        OpenGLBackend(),
                        OpenGLESBackend(),
                        VulkanBackend());
  