DirectX 12 API Reference

ID3D12Device::CreateCommandAllocator

HRESULT CreateCommandAllocator( [in] D3D12_COMMAND_LIST_TYPE type, [in] REFIID riid, [out] void **ppCommandAllocator );

Description

Creates a command allocator object. A command allocator is required to record commands into a command list. Each command list must have its own command allocator.

Parameters

  • type: A D3D12_COMMAND_LIST_TYPE enumerated value that specifies the type of command list that the command allocator is associated with.
  • riid: The globally unique identifier (GUID) for the command allocator interface (e.g., IID_ID3D12CommandAllocator).
  • ppCommandAllocator: A pointer to a memory location that receives a pointer to the ID3D12CommandAllocator interface for the command allocator.

Return Value

Returns S_OK if successful, or an appropriate error code from Direct3D 12 Error Codes.

Remarks

A command allocator provides memory for recording command lists. When you create a command list, you must provide a command allocator that matches the command list's type. You can reset a command allocator to reuse it for recording new commands. This is more efficient than creating a new command allocator for each command list.

See Also

ID3D12GraphicsCommandList::DrawInstanced

void DrawInstanced( [in] UINT VertexCountPerInstance, [in] UINT InstanceCount, [in] UINT StartVertexLocation, [in] UINT StartInstanceLocation );

Description

Draws a range of vertices, taking an instance count into account.

Parameters

  • VertexCountPerInstance: The number of vertices to draw for each instance.
  • InstanceCount: The number of instances to draw.
  • StartVertexLocation: The starting vertex for the first vertex to draw.
  • StartInstanceLocation: The starting instance to draw.

Remarks

This method is used to draw geometry that consists of multiple instances. Instancing is a technique used to draw the same geometry multiple times with different transformations, colors, or other data per instance.

See Also

D3D12_RESOURCE_DESC

typedef struct D3D12_RESOURCE_DESC { D3D12_RESOURCE_DIMENSION Dimension; UINT64 Alignment; UINT64 Width; UINT Height; UINT16 DepthOrArraySize; UINT16 MipLevels; D3D12_FORMAT Format; D3D12_SAMPLE_DESC SampleDesc; D3D12_TEXTURE_LAYOUT Layout; D3D12_RESOURCE_FLAGS Flags; } D3D12_RESOURCE_DESC;

Description

Describes a resource.

Members

  • Dimension: A D3D12_RESOURCE_DIMENSION enumerated value that specifies the dimensions of the resource.
  • Alignment: The memory alignment for the resource. Must be 0, 4 KB, 64 KB, or 128 KB.
  • Width: The width of the resource (e.g., in texels for a texture, or bytes for a buffer).
  • Height: The height of the resource (e.g., in texels for a texture). For a buffer, set to 1.
  • DepthOrArraySize: The depth of the resource (for 3D textures) or the number of arrays (for texture arrays). For a buffer, set to 1.
  • MipLevels: The number of mipmap levels in the resource.
  • Format: A D3D12_FORMAT enumerated value that specifies the format of the resource.
  • SampleDesc: A D3D12_SAMPLE_DESC structure that describes the multi-sampling parameters for the resource.
  • Layout: A D3D12_TEXTURE_LAYOUT enumerated value that specifies the memory layout of the resource.
  • Flags: A D3D12_RESOURCE_FLAGS enumerated value that specifies resource flags (e.g., CPU read access, render target).

See Also