인덱스 버퍼, 상수 버퍼의 사용

ID3D11Buffer *g_pIndexBuffer = NULL; // Create indices. unsigned int indices[] = { 0, 1, 2 }; // Fill in a buffer description. D3D11_BUFFER_DESC bufferDesc; bufferDesc.Usage = D3D11_USAGE_DEFAULT; bufferDesc.ByteWidth = sizeof( unsigned int ) * 3; bufferDesc.BindFlags = D3D11_BIND_INDEX_BUFFER; bufferDesc.CPUAccessFlags = 0; bufferDesc.MiscFlags = 0; // Define the resource data. D3D11_SUBRESOURCE_DATA InitData; InitData.pSysMem = indices; InitData.SysMemPitch = 0; InitData.SysMemSlicePitch = 0; // Create the buffer with the device. hr = g_pd3dDevice->CreateBuffer( &bufferDesc, &InitData, &g_pIndexBuffer ); if( FAILED( hr ) ) return hr; // Set the buffer. g_pd3dContext->IASetIndexBuffer( g_pIndexBuffer, DXGI_FORMAT_R32_UINT, 0 );

void IASetIndexBuffer( ID3D11Buffer *pIndexBuffer, // 인덱스 버퍼 DXGI_FORMAT Format, // 인덱스 포맷 UINT Offset // 시작 오프셋 (바이트) );

ID3D11Buffer* g_pConstantBuffer11 = NULL; // Define the constant data used to communicate with shaders. struct VS_CONSTANT_BUFFER { XMFLOAT4X4 mWorldViewProj; XMFLOAT4 vSomeVectorThatMayBeNeededByASpecificShader; float fSomeFloatThatMayBeNeededByASpecificShader; float fTime; float fSomeFloatThatMayBeNeededByASpecificShader2; float fSomeFloatThatMayBeNeededByASpecificShader3; }; // Supply the vertex shader constant data. VS_CONSTANT_BUFFER VsConstData; VsConstData.mWorldViewProj = {...}; VsConstData.vSomeVectorThatMayBeNeededByASpecificShader = XMFLOAT4(1,2,3,4); VsConstData.fSomeFloatThatMayBeNeededByASpecificShader = 3.0f; VsConstData.fTime = 1.0f; VsConstData.fSomeFloatThatMayBeNeededByASpecificShader2 = 2.0f; VsConstData.fSomeFloatThatMayBeNeededByASpecificShader3 = 4.0f; // Fill in a buffer description. D3D11_BUFFER_DESC cbDesc; cbDesc.ByteWidth = sizeof( VS_CONSTANT_BUFFER ); cbDesc.Usage = D3D11_USAGE_DYNAMIC; cbDesc.BindFlags = D3D11_BIND_CONSTANT_BUFFER; cbDesc.CPUAccessFlags = D3D11_CPU_ACCESS_WRITE; cbDesc.MiscFlags = 0; cbDesc.StructureByteStride = 0; // Fill in the subresource data. D3D11_SUBRESOURCE_DATA InitData; InitData.pSysMem = &VsConstData; InitData.SysMemPitch = 0; InitData.SysMemSlicePitch = 0; // Create the buffer. hr = g_pd3dDevice->CreateBuffer( &cbDesc, &InitData, &g_pConstantBuffer11 ); if( FAILED( hr ) ) return hr; // Set the buffer. g_pd3dContext->VSSetConstantBuffers( 0, 1, &g_pConstantBuffer11 );

cbDesc.Usage = D3D11_USAGE_DYNAMIC; cbDesc.CPUAccessFlags = D3D11_CPU_ACCESS_WRITE;

void VSSetConstantBuffers( UINT StartSlot, // 시작 슬롯 번호 UINT NumBuffers, // 버퍼 개수 ID3D11Buffer *const *ppConstantBuffers // 버퍼 배열 );

void UpdateConstantBuffer(ID3D11DeviceContext* context, ID3D11Buffer* constantBuffer, const MyConstantData& data) { D3D11_MAPPED_SUBRESOURCE mappedResource; // 버퍼를 CPU 메모리에 매핑 HRESULT hr = context->Map( constantBuffer, 0, D3D11_MAP_WRITE_DISCARD, // 기존 데이터 폐기 0, &mappedResource ); if (SUCCEEDED(hr)) { // 데이터 복사 memcpy(mappedResource.pData, &data, sizeof(MyConstantData)); // 매핑 해제 context->Unmap(constantBuffer, 0); } }

void UpdateConstantBufferDefault(ID3D11DeviceContext* context, ID3D11Buffer* constantBuffer, const MyConstantData& data) { // UpdateSubresource로 직접 업데이트 context->UpdateSubresource( constantBuffer, 0, nullptr, &data, 0, 0 ); }

// 상수 버퍼 구조체 정의 struct TransformCB { Matrix world; Matrix view; Matrix projection; }; // 생성 D3D11_BUFFER_DESC cbDesc = {}; cbDesc.ByteWidth = sizeof(TransformCB); cbDesc.Usage = D3D11_USAGE_DYNAMIC; cbDesc.BindFlags = D3D11_BIND_CONSTANT_BUFFER; cbDesc.CPUAccessFlags = D3D11_CPU_ACCESS_WRITE; ID3D11Buffer* transformCB = nullptr; device->CreateBuffer(&cbDesc, nullptr, &transformCB); // 매 프레임 업데이트 void Render() { TransformCB cbData; cbData.world = GetWorldMatrix(); cbData.view = GetViewMatrix(); cbData.projection = GetProjectionMatrix(); D3D11_MAPPED_SUBRESOURCE mapped; context->Map(transformCB, 0, D3D11_MAP_WRITE_DISCARD, 0, &mapped); memcpy(mapped.pData, &cbData, sizeof(TransformCB)); context->Unmap(transformCB, 0); context->VSSetConstantBuffers(0, 1, &transformCB); // Draw... }

struct MaterialCB { Vector4 albedoColor; float metallic; float roughness; float ao; float padding; }; // Material 변경 시 업데이트 void SetMaterial(const Material& material) { MaterialCB cbData; cbData.albedoColor = material.albedoColor; cbData.metallic = material.metallic; cbData.roughness = material.roughness; cbData.ao = material.ao; context->UpdateSubresource(materialCB, 0, nullptr, &cbData, 0, 0); context->PSSetConstantBuffers(1, 1, &materialCB); }

// 나쁜 예: 비효율적인 패킹 struct BadCB { float value1; // 0-3 bytes // 12 bytes 패딩! float4 vector; // 16-31 bytes float value2; // 32-35 bytes // 12 bytes 패딩! // 총 48 bytes }; // 좋은 예: 효율적인 패킹 struct GoodCB { float4 vector; // 0-15 bytes float value1; // 16-19 bytes float value2; // 20-23 bytes float padding1; // 24-27 bytes float padding2; // 28-31 bytes // 총 32 bytes (33% 절약) };

// 업데이트 빈도에 따라 분할 cbuffer PerFrame : register(b0) // 매 프레임 { float4x4 view; float4x4 projection; float time; }; cbuffer PerObject : register(b1) // 오브젝트마다 { float4x4 world; }; cbuffer PerMaterial : register(b2) // Material마다 { float4 albedoColor; float metallic; float roughness; };

// 나쁜 예: 매번 업데이트 for (auto& obj : objects) { UpdateConstantBuffer(obj.transform); Draw(obj); } // 좋은 예: 같은 데이터는 한 번만 UpdateConstantBuffer(sharedData); for (auto& obj : objects) { if (obj.needsUpdate) { UpdateConstantBuffer(obj.transform); } Draw(obj); }

class ConstantBufferCache { std::vector<byte> cachedData; bool NeedsUpdate(const void* newData, size_t size) { if (cachedData.size() != size) return true; return memcmp(cachedData.data(), newData, size) != 0; } void Update(ID3D11Buffer* cb, const void* newData, size_t size) { if (NeedsUpdate(newData, size)) { // 실제로 변경된 경우에만 업데이트 UpdateConstantBuffer(cb, newData, size); cachedData.assign((byte*)newData, (byte*)newData + size); } } };