Studying D3D12HelloConstBuffers desktop sample

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

•Describe how to pass constant buffer to shaders.

Diff from D3DXHelloTriangle.h

struct SceneConstantBuffer

    {

        XMFLOAT4 offset;

    };

SceneConstantBuffer m_constantBufferData;

// constant buffer view (CBV) descriptor heap.

ComPtr<ID3D12DescriptorHeap> m_cbvHeap;

ComPtr<ID3D12Resource> m_constantBuffer;

UINT8* m_pCbvDataBegin;

D3D12HelloConstBuffers objects and their relations

•m_constantBuffer->Map() is called to get mapped pointer m_cbvDataBegin on OnInit() and m_constantBuffer is never Unmap() ed. Keep constant buffer mapped is OK

•OnUpdate(), constant buffer data is updated and memcpy() ed to m_cbvDataBegin.

•m_commandList->SetDescriptorHeaps() and m_commandList->SetGraphicsRootDesrptorTable() to set m_cbvHeap.

•on Shaders.hlsl, constant buffer is exposed at register(b0):

cbuffer SceneConstantBuffer : register(b0)

{

    float4 offset;

};