BufferHelpers

DirectXTK

Helpers functions for creating Direct3D resources from CPU data.

Header

#include <BufferHelpers.h>

Creating vertex/index buffers

The CreateStaticBuffer helper is used to create Direct3D buffer type resources such as vertex buffers or index buffers.

HRESULT CreateStaticBuffer(ID3D11Device* device,
    const void* ptr, size_t count, size_t stride,
    unsigned int bindFlags,
    ID3D11Buffer** pBuffer);

template<typename T>
HRESULT CreateStaticBuffer(ID3D11Device* device,
    T const* data,
    size_t count,
    unsigned int bindFlags,
    ID3D11Buffer** pBuffer);

template<typename T>
HRESULT CreateStaticBuffer(ID3D11Device* device,
    T const& data,
    unsigned int bindFlags,
    ID3D11Buffer** pBuffer);

Parameters

bindFlags is one or more D3D11_BIND_FLAG values. Typically D3D11_BIND_VERTEX_BUFFER for vertex buffers, or D3D11_BIND_INDEX_BUFFER for an index buffer.

Examples

static const VertexPositionColor s_vertexData[3] =
{
    { XMFLOAT3{ 0.0f,   0.5f,  0.5f }, XMFLOAT4{ 1.0f, 0.0f, 0.0f, 1.0f } },  // Top / Red
    { XMFLOAT3{ 0.5f,  -0.5f,  0.5f }, XMFLOAT4{ 0.0f, 1.0f, 0.0f, 1.0f } },  // Right / Green
    { XMFLOAT3{ -0.5f, -0.5f,  0.5f }, XMFLOAT4{ 0.0f, 0.0f, 1.0f, 1.0f } }   // Left / Blue
};

ComPtr<ID3D11Buffer> vb;
DX::ThrowIfFailed(
  CreateStaticBuffer(device,
    s_vertexData,                // const void *ptr
    std::size(s_vertexData),     // size_t count
    sizeof(VertexPositionColor), // size_t stride
    D3D11_BIND_VERTEX_BUFFER, &vb)
  );

When creating from an array using VertexTypes, a template simplifies this to:

ComPtr<ID3D11Buffer> vb;
DX::ThrowIfFailed(
  CreateStaticBuffer(device, s_vertexData, std::size(s_vertexData),
    D3D11_BIND_VERTEX_BUFFER, &vb)
  );

Finally, you can create from C++ containers like std::vector:

std::vector<uint16_t> indices;

...

ComPtr<ID3D11Buffer> ib;
DX::ThrowIfFailed(
  CreateStaticBuffer(device, indices, D3D11_BIND_INDEX_BUFFER, &ib)
  );

Note that using std::vector<uint32_t> indices; requires Direct3D Feature level 9.2 or better.

See Model for creating vertex buffers/index buffers from disk files.

Creating textures

The CreateTextureFromMemory helpers can be used to create Direct3D 1D, 2D, or 3D texture resources. For the 2D version, you can enable auto-generation of mipmaps.

HRESULT CreateTextureFromMemory(ID3D11Device* device,
    size_t width,
    DXGI_FORMAT format,
    const D3D11_SUBRESOURCE_DATA& initData,
    ID3D11Texture1D** texture,
    ID3D11ShaderResourceView** textureView,
    unsigned int bindFlags = D3D11_BIND_SHADER_RESOURCE);

HRESULT CreateTextureFromMemory(ID3D11Device* device,
    size_t width, size_t height,
    DXGI_FORMAT format,
    const D3D11_SUBRESOURCE_DATA& initData,
    ID3D11Texture2D** texture,
    ID3D11ShaderResourceView** textureView,
    unsigned int bindFlags = D3D11_BIND_SHADER_RESOURCE);

HRESULT  CreateTextureFromMemory(ID3D11Device* device,
    ID3D11DeviceContext* d3dContext,
    size_t width, size_t height,
    DXGI_FORMAT format,
    const D3D11_SUBRESOURCE_DATA& initData,
    ID3D11Texture2D** texture,
    ID3D11ShaderResourceView** textureView);

HRESULT CreateTextureFromMemory(ID3D11Device* device,
    size_t width, size_t height, size_t depth,
    DXGI_FORMAT format,
    const D3D11_SUBRESOURCE_DATA& initData,
    ID3D11Texture3D** texture,
    ID3D11ShaderResourceView** textureView,
    unsigned int bindFlags = D3D11_BIND_SHADER_RESOURCE);

Parameters

bindFlags is one or more D3D11_BIND_FLAG values. Typically D3D11_BIND_SHADER_RESOURCE textures.

Either texture or textureView can be nullptr, but not both. In most use cases for rendering, you only need the shader resource view (SRV) textureView interface.

The version that takes a d3dContext will attempt to use the auto-generation of mipmaps features in the Direct3D 11 API if supported for the pixel format. Note the quality of auto-gen mipmaps is up to the driver, so can vary widely. Also if a context is passed, the function is not thread safe.

Examples

To create a 'default' texture (i.e. a 1x1 white pixel):

const uint32_t s_pixel = 0xffffffff;

D3D11_SUBRESOURCE_DATA initData = { &s_pixel, sizeof(uint32_t), 0 };

ComPtr<ID3D11ShaderResourceView> defaultTex;
DX::ThrowIfFailed(
    CreateTextureFromMemory(device, 1u, 1u, DXGI_FORMAT_R8G8B8A8_UNORM, initData,
        nullptr, &defaultTex)
    );

See DDSTextureLoader and WICTextureLoader for creating textures from disk files.

Constant buffers

The ConstantBuffer template class is a strongly-typed helper for managing constant buffers.

struct MyCB
{
    XMMATRIX world;
};

static_assert((sizeof(MyCB) % 16) == 0, "CB size not padded correctly");

ConstantBuffer<MyCB> cbuffer;

...

cbuffer.Create(device);

...


MyCB updates = { ... };
cbuffer.SetData(deviceContext, updates);

auto buffer = cbuffer.GetBuffer();

deviceContext->VSSetConstantBuffers(0, 1, &buffer);
deviceContext->PSSetConstantBuffers(0, 1, &buffer);

For Xbox One XDK, the ConstantBuffer class supports "11.X fast semantics", requiring a slightly different calling pattern when rendering. Each time you call SetData the GraphicsMemory class is used to allocate video memory.

void *grfxMemory;
cbuffer.SetData(deviceContext, constants, &grfxMemory);

auto buffer = cbuffer.GetBuffer();

deviceContextX->VSSetPlacementConstantBuffer(0, buffer, grfxMemory);
deviceContextX->PSSetPlacementConstantBuffer(0, buffer, grfxMemory);