Implement Culling and FrontFace

This patch implements Culling and FrontFace on backends, and add tests too.

This test also verified that we couldn't invert FrontFace on Metal backend.
Otherwise, the tests would fail on all HWs.

But we do need to invert CCW/CW on OpenGL backend. Because Y axis is up in
OpenGL while Y axis is down in WebGPU.

Bug=dawn:43

Change-Id: I7dd0922477397a13c5f7208e104ff352a673a556
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/8420
Reviewed-by: Kai Ninomiya <kainino@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Yunchao He <yunchao.he@intel.com>

src/tests/end2end/CullingTests.cpp

@@ -0,0 +1,127 @@
+// 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 "tests/DawnTest.h"
+
+#include "utils/ComboRenderPipelineDescriptor.h"
+#include "utils/DawnHelpers.h"
+
+class CullingTest : public DawnTest {
+  protected:
+    dawn::RenderPipeline CreatePipelineForTest(dawn::FrontFace frontFace, dawn::CullMode cullMode) {
+        utils::ComboRenderPipelineDescriptor pipelineDescriptor(device);
+
+        // Draw two triangles with different winding orders:
+        // 1. The top-left one is counterclockwise (CCW)
+        // 2. The bottom-right one is clockwise (CW)
+        const char* vs =
+            R"(#version 450
+        const vec2 pos[6] = vec2[6](vec2(-1.0f, -1.0f),
+                                    vec2(-1.0f,  0.0f),
+                                    vec2( 0.0f, -1.0f),
+                                    vec2( 0.0f,  1.0f),
+                                    vec2( 1.0f,  0.0f),
+                                    vec2( 1.0f,  1.0f));
+        void main() {
+           gl_Position = vec4(pos[gl_VertexIndex], 0.0, 1.0);
+       })";
+        pipelineDescriptor.cVertexStage.module =
+            utils::CreateShaderModule(device, dawn::ShaderStage::Vertex, vs);
+
+        const char* fs =
+            "#version 450\n"
+            "layout(location = 0) out vec4 fragColor;"
+            "void main() {\n"
+            "   fragColor = vec4(1.0, 0.0, 0.0, 1.0);\n"
+            "}\n";
+        pipelineDescriptor.cFragmentStage.module =
+            utils::CreateShaderModule(device, dawn::ShaderStage::Fragment, fs);
+
+        // Set culling mode and front face according to the parameters
+        pipelineDescriptor.cRasterizationState.frontFace = frontFace;
+        pipelineDescriptor.cRasterizationState.cullMode = cullMode;
+
+        return device.CreateRenderPipeline(&pipelineDescriptor);
+    }
+
+    dawn::Texture Create2DTextureForTest(dawn::TextureFormat format) {
+        dawn::TextureDescriptor textureDescriptor;
+        textureDescriptor.dimension = dawn::TextureDimension::e2D;
+        textureDescriptor.format = format;
+        textureDescriptor.usage =
+            dawn::TextureUsageBit::OutputAttachment | dawn::TextureUsageBit::TransferSrc;
+        textureDescriptor.arrayLayerCount = 1;
+        textureDescriptor.mipLevelCount = 1;
+        textureDescriptor.sampleCount = 1;
+        textureDescriptor.size = {kSize, kSize, 1};
+        return device.CreateTexture(&textureDescriptor);
+    }
+
+    void DoTest(dawn::FrontFace frontFace,
+                dawn::CullMode cullMode,
+                bool isCCWTriangleCulled,
+                bool isCWTriangleCulled) {
+        dawn::Texture colorTexture = Create2DTextureForTest(dawn::TextureFormat::RGBA8Unorm);
+
+        utils::ComboRenderPassDescriptor renderPassDescriptor({colorTexture.CreateDefaultView()});
+        renderPassDescriptor.cColorAttachmentsInfoPtr[0]->clearColor = {0.0, 1.0, 0.0, 1.0};
+        renderPassDescriptor.cColorAttachmentsInfoPtr[0]->loadOp = dawn::LoadOp::Clear;
+
+        dawn::CommandEncoder commandEncoder = device.CreateCommandEncoder();
+        dawn::RenderPassEncoder renderPass = commandEncoder.BeginRenderPass(&renderPassDescriptor);
+        renderPass.SetPipeline(CreatePipelineForTest(frontFace, cullMode));
+        renderPass.Draw(6, 1, 0, 0);
+        renderPass.EndPass();
+        dawn::CommandBuffer commandBuffer = commandEncoder.Finish();
+        dawn::Queue queue = device.CreateQueue();
+        queue.Submit(1, &commandBuffer);
+
+        constexpr RGBA8 kDrawingColor = RGBA8(255, 0, 0, 255);
+        constexpr RGBA8 kBackgroundColor = RGBA8(0, 255, 0, 255);
+
+        RGBA8 kCCWTriangleColor = isCCWTriangleCulled ? kBackgroundColor : kDrawingColor;
+        EXPECT_PIXEL_RGBA8_EQ(kCCWTriangleColor, colorTexture, 0, 0);
+
+        RGBA8 kCWTriangleColor = isCWTriangleCulled ? kBackgroundColor : kDrawingColor;
+        EXPECT_PIXEL_RGBA8_EQ(kCWTriangleColor, colorTexture, kSize - 1, kSize - 1);
+    }
+
+    static constexpr uint32_t kSize = 4;
+};
+
+TEST_P(CullingTest, CullNoneWhenCCWIsFrontFace) {
+    DoTest(dawn::FrontFace::CCW, dawn::CullMode::None, false, false);
+}
+
+TEST_P(CullingTest, CullFrontFaceWhenCCWIsFrontFace) {
+    DoTest(dawn::FrontFace::CCW, dawn::CullMode::Front, true, false);
+}
+
+TEST_P(CullingTest, CullBackFaceWhenCCWIsFrontFace) {
+    DoTest(dawn::FrontFace::CCW, dawn::CullMode::Back, false, true);
+}
+
+TEST_P(CullingTest, CullNoneWhenCWIsFrontFace) {
+    DoTest(dawn::FrontFace::CW, dawn::CullMode::None, false, false);
+}
+
+TEST_P(CullingTest, CullFrontFaceWhenCWIsFrontFace) {
+    DoTest(dawn::FrontFace::CW, dawn::CullMode::Front, false, true);
+}
+
+TEST_P(CullingTest, CullBackFaceWhenCWIsFrontFace) {
+    DoTest(dawn::FrontFace::CW, dawn::CullMode::Back, true, false);
+}
+
+DAWN_INSTANTIATE_TEST(CullingTest, D3D12Backend, MetalBackend, OpenGLBackend, VulkanBackend);