+ 添加箱子的alpha绘制

* 箱子的alpha绘制，需要修改ps shader，alpha值小于0.1的就不输出颜色了。
* 对于这种绘制需求，因为需要看到透过去的部分，添加一个不做背面剔除的PSO
* GraphicsCore再调用update时的入参，在关闭了垂直同步的情况下，第二次的update会传入一个极大值。
对变量s_FrameStartTick添加初始化

Author: [email protected]

Chapter 10 Blending/Core/Graphics/GraphicsCore.cpp

@@ -525,6 +525,7 @@ bool Graphics::Initialize(void)
 //     GraphRenderer::Initialize();
 //     ParticleEffects::Initialize(kMaxNativeWidth, kMaxNativeHeight);
 
+    s_FrameStartTick = SystemTime::GetCurrentTick();;
     return true;
 }
 

Chapter 10 Blending/Core/Shaders/defaultPS.hlsl

@@ -59,6 +59,12 @@ float4 main(VertexOut pin) : SV_Target0
 {
     float4 diffuseAlbedo = gDiffuseMap.Sample(gsamAnisotropicWrap, pin.TexC) * gDiffuseAlbedo;
 
+    // ͸Ã÷ÏñËصãÌÞ³ý
+    // Discard pixel if texture alpha < 0.1.  We do this test as soon 
+    // as possible in the shader so that we can potentially exit the
+    // shader early, thereby skipping the rest of the shader code.
+    clip(diffuseAlbedo.a - 0.1f);
+
     // Interpolating normal can unnormalize it, so renormalize it.
     pin.NormalW = normalize(pin.NormalW);
 

Chapter 10 Blending/GameApp.cpp

@@ -81,6 +81,15 @@ void GameApp::Startup(void)
     wireFramPSO.SetRasterizerState(raster);
     wireFramPSO.Finalize();
     m_mapPSO[E_EPT_WIREFRAME] = wireFramPSO;
+
+    // alpha test PSO
+    // 对于本例箱子一些面是透明的，要求显示到背面的东西
+    GraphicsPSO alphaTestPSO = defaultPSO;
+    raster = Graphics::RasterizerDefault;
+    raster.CullMode = D3D12_CULL_MODE_NONE;
+    alphaTestPSO.SetRasterizerState(raster);
+    alphaTestPSO.Finalize();
+    m_mapPSO[E_EPT_ALPHATEST] = alphaTestPSO;
 }
 
 void GameApp::Cleanup(void)
@@ -418,7 +427,7 @@ void GameApp::buildLandAndWaves()
     const ManagedTexture* MatTextures[3] = {};
     MatTextures[0] = TextureManager::LoadFromFile(L"grass", true);
     MatTextures[1] = TextureManager::LoadFromFile(L"water1", true);
-    MatTextures[2] = TextureManager::LoadFromFile(L"WoodCrate01", true);
+    MatTextures[2] = TextureManager::LoadFromFile(L"WireFence", true);
 
     GeometryGenerator geoGen;
     GeometryGenerator::MeshData grid = geoGen.CreateGrid(160.0f, 160.0f, 50, 50);
@@ -594,6 +603,8 @@ void GameApp::renderLandAndWaves(GraphicsContext& gfxContext)
 
         setShaderParam(gfxContext, m_renderItemBox);
 
+        gfxContext.SetPipelineState(m_mapPSO[E_EPT_ALPHATEST]);
+
         // 绘制
         gfxContext.DrawIndexedInstanced(m_IndexBufferBox.GetElementCount(), 1, 0, 0, 0);
     }

Chapter 10 Blending/GameApp.h

@@ -64,11 +64,12 @@ class GameApp : public GameCore::IGameApp
     enum ePSOType
     {
         E_EPT_DEFAULT = 1,
-        E_EPT_WIREFRAME = 2
+        E_EPT_WIREFRAME = 2,
+        E_EPT_ALPHATEST = 3,
     };
     std::unordered_map<int, GraphicsPSO> m_mapPSO;
 
-    bool m_bRenderShapes = true;
+    bool m_bRenderShapes = false;
     bool m_bRenderFill = true;
 
     // shapes