Studying D3D12HelloTexture desktop project

•DirectX-Graphics-Samples-master\Samples\Desktop\D3D12HelloWorld\src\HelloTexture

•Paints 2d texture (checkerboard image) to triangle.

Difference from D3D12HelloTriangle

 

Took diff with WinMerge to find difference.

•D3D12HelloTexture.h

– static const UINT TextureWidth = 256;

– static const UINT TextureHeight = 256;

– static const UINT TexturePixelSize = 4;

– struct Vertex

–    {

–        XMFLOAT3 position;

–        XMFLOAT2 uv; //< texture UV instead of vertex color.

–    };

–ComPtr<ID3D12DescriptorHeap> m_srvHeap;

–ComPtr<ID3D12Resource> m_texture;

Texture UV corrdinate

Direct X traditionally uses right=X+, down=Y+ coordinates for UV.

 

 Objects and their relations

 Changes from HelloTriangle example is highlighted in orange.

 

•m_texture

–width=256px, height=256px, pixelformat=RGBA8888

–mipmap level=1

–initialized as COPY_DEST state (ready to update texture image)

–UpdateSubResources() to upload texture image of CPU memory to texture GPU memory

–change resource state to PIXEL_SHADER_RESOURCE for pixel shader to read

•sampler

–defines texture sampler behavior such as texture clamp and mip map parameters.

–m_rootSignature has this sampler info.

•m_srvHeap (Shader Resource View heap)

–Pixel shader sees m_texture via m_srvHeap.

–m_commandList connects m_srvHeap via those calls:

ID3D12DescriptorHeap* ppHeaps[] = { m_srvHeap.Get() };

m_commandList->SetDescriptorHeaps(_countof(ppHeaps), ppHeaps);

m_commandList->SetGraphicsRootDescriptorTable(

  0, m_srvHeap->GetGPUDescriptorHandleForHeapStart());

 

PipelineStateDesc.InputLayout is changed to input texture UV instead of vertex color.

 Shader code

 DirectX-Graphics-Samples-master\Samples\Desktop\D3D12HelloWorld\src\HelloTexture\shaders.hlsl

Vertex shader pass through input position and UV value.

Pixel shader samples texture to get pixel color.