CUDA Driver API :: CUDA Toolkit Documentation

6.28. Texture Object Management

This section describes the texture object management functions of the low-level CUDA driver application programming interface. The texture object API is only supported on devices of compute capability 3.0 or higher.

Functions

CUresult cuTexObjectCreate ( CUtexObject* pTexObject, const CUDA_RESOURCE_DESC* pResDesc, const CUDA_TEXTURE_DESC* pTexDesc, const CUDA_RESOURCE_VIEW_DESC* pResViewDesc ): Creates a texture object.
CUresult cuTexObjectDestroy ( CUtexObject texObject ): Destroys a texture object.
CUresult cuTexObjectGetResourceDesc ( CUDA_RESOURCE_DESC* pResDesc, CUtexObject texObject ): Returns a texture object's resource descriptor.
CUresult cuTexObjectGetResourceViewDesc ( CUDA_RESOURCE_VIEW_DESC* pResViewDesc, CUtexObject texObject ): Returns a texture object's resource view descriptor.
CUresult cuTexObjectGetTextureDesc ( CUDA_TEXTURE_DESC* pTexDesc, CUtexObject texObject ): Returns a texture object's texture descriptor.

Functions

CUresult cuTexObjectCreate ( CUtexObject* pTexObject, const CUDA_RESOURCE_DESC* pResDesc, const CUDA_TEXTURE_DESC* pTexDesc, const CUDA_RESOURCE_VIEW_DESC* pResViewDesc )

Creates a texture object.

Parameters

pTexObject: - Texture object to create
pResDesc: - Resource descriptor
pTexDesc: - Texture descriptor
pResViewDesc: - Resource view descriptor

Returns

CUDA_SUCCESS, CUDA_ERROR_DEINITIALIZED, CUDA_ERROR_NOT_INITIALIZED, CUDA_ERROR_INVALID_CONTEXT, CUDA_ERROR_INVALID_VALUE

Description

Creates a texture object and returns it in pTexObject. pResDesc describes the data to texture from. pTexDesc describes how the data should be sampled. pResViewDesc is an optional argument that specifies an alternate format for the data described by pResDesc, and also describes the subresource region to restrict access to when texturing. pResViewDesc can only be specified if the type of resource is a CUDA array or a CUDA mipmapped array not in a block compressed format.

Texture objects are only supported on devices of compute capability 3.0 or higher. Additionally, a texture object is an opaque value, and, as such, should only be accessed through CUDA API calls.

The CUDA_RESOURCE_DESC structure is defined as:

‎        typedef struct CUDA_RESOURCE_DESC_st
              {
                  CUresourcetype resType;
      
                  union {
                      struct {
                          CUarray hArray;
                      } array;
                      struct {
                          CUmipmappedArray hMipmappedArray;
                      } mipmap;
                      struct {
                          CUdeviceptr devPtr;
                          CUarray_format format;
                          unsigned int numChannels;
                          size_t sizeInBytes;
                      } linear;
                      struct {
                          CUdeviceptr devPtr;
                          CUarray_format format;
                          unsigned int numChannels;
                          size_t width;
                          size_t height;
                          size_t pitchInBytes;
                      } pitch2D;
                  } res;
      
                  unsigned int flags;
              } CUDA_RESOURCE_DESC;

where:

CUDA_RESOURCE_DESC::resType specifies the type of resource to texture from. CUresourceType is defined as:

‎        typedef enum CUresourcetype_enum {
                  CU_RESOURCE_TYPE_ARRAY           = 0x00,
                  CU_RESOURCE_TYPE_MIPMAPPED_ARRAY = 0x01,
                  CU_RESOURCE_TYPE_LINEAR          = 0x02,
                  CU_RESOURCE_TYPE_PITCH2D         = 0x03
              } CUresourcetype;

If CUDA_RESOURCE_DESC::resType is set to CU_RESOURCE_TYPE_ARRAY, CUDA_RESOURCE_DESC::res::array::hArray must be set to a valid CUDA array handle.

If CUDA_RESOURCE_DESC::resType is set to CU_RESOURCE_TYPE_MIPMAPPED_ARRAY, CUDA_RESOURCE_DESC::res::mipmap::hMipmappedArray must be set to a valid CUDA mipmapped array handle.

If CUDA_RESOURCE_DESC::resType is set to CU_RESOURCE_TYPE_LINEAR, CUDA_RESOURCE_DESC::res::linear::devPtr must be set to a valid device pointer, that is aligned to CU_DEVICE_ATTRIBUTE_TEXTURE_ALIGNMENT. CUDA_RESOURCE_DESC::res::linear::format and CUDA_RESOURCE_DESC::res::linear::numChannels describe the format of each component and the number of components per array element. CUDA_RESOURCE_DESC::res::linear::sizeInBytes specifies the size of the array in bytes. The total number of elements in the linear address range cannot exceed CU_DEVICE_ATTRIBUTE_MAXIMUM_TEXTURE1D_LINEAR_WIDTH. The number of elements is computed as (sizeInBytes / (sizeof(format) * numChannels)).

If CUDA_RESOURCE_DESC::resType is set to CU_RESOURCE_TYPE_PITCH2D, CUDA_RESOURCE_DESC::res::pitch2D::devPtr must be set to a valid device pointer, that is aligned to CU_DEVICE_ATTRIBUTE_TEXTURE_ALIGNMENT. CUDA_RESOURCE_DESC::res::pitch2D::format and CUDA_RESOURCE_DESC::res::pitch2D::numChannels describe the format of each component and the number of components per array element. CUDA_RESOURCE_DESC::res::pitch2D::width and CUDA_RESOURCE_DESC::res::pitch2D::height specify the width and height of the array in elements, and cannot exceed CU_DEVICE_ATTRIBUTE_MAXIMUM_TEXTURE2D_LINEAR_WIDTH and CU_DEVICE_ATTRIBUTE_MAXIMUM_TEXTURE2D_LINEAR_HEIGHT respectively. CUDA_RESOURCE_DESC::res::pitch2D::pitchInBytes specifies the pitch between two rows in bytes and has to be aligned to CU_DEVICE_ATTRIBUTE_TEXTURE_PITCH_ALIGNMENT. Pitch cannot exceed CU_DEVICE_ATTRIBUTE_MAXIMUM_TEXTURE2D_LINEAR_PITCH.

flags must be set to zero.

The CUDA_TEXTURE_DESC struct is defined as

‎        typedef struct CUDA_TEXTURE_DESC_st {
                  CUaddress_mode addressMode[3];
                  CUfilter_mode filterMode;
                  unsigned int flags;
                  unsigned int maxAnisotropy;
                  CUfilter_mode mipmapFilterMode;
                  float mipmapLevelBias;
                  float minMipmapLevelClamp;
                  float maxMipmapLevelClamp;
              } CUDA_TEXTURE_DESC;

where

CUDA_TEXTURE_DESC::addressMode specifies the addressing mode for each dimension of the texture data. CUaddress_mode is defined as:

‎        typedef enum CUaddress_mode_enum {
                  CU_TR_ADDRESS_MODE_WRAP = 0,
                  CU_TR_ADDRESS_MODE_CLAMP = 1,
                  CU_TR_ADDRESS_MODE_MIRROR = 2,
                  CU_TR_ADDRESS_MODE_BORDER = 3
              } CUaddress_mode;

This is ignored if CUDA_RESOURCE_DESC::resType is CU_RESOURCE_TYPE_LINEAR. Also, if the flag, CU_TRSF_NORMALIZED_COORDINATES is not set, the only supported address mode is CU_TR_ADDRESS_MODE_CLAMP.

CUDA_TEXTURE_DESC::filterMode specifies the filtering mode to be used when fetching from the texture. CUfilter_mode is defined as:

‎        typedef enum CUfilter_mode_enum {
                  CU_TR_FILTER_MODE_POINT = 0,
                  CU_TR_FILTER_MODE_LINEAR = 1
              } CUfilter_mode;

This is ignored if CUDA_RESOURCE_DESC::resType is CU_RESOURCE_TYPE_LINEAR.

CUDA_TEXTURE_DESC::flags can be any combination of the following:
- CU_TRSF_READ_AS_INTEGER, which suppresses the default behavior of having the texture promote integer data to floating point data in the range [0, 1]. Note that texture with 32-bit integer format would not be promoted, regardless of whether or not this flag is specified.
- CU_TRSF_NORMALIZED_COORDINATES, which suppresses the default behavior of having the texture coordinates range from [0, Dim) where Dim is the width or height of the CUDA array. Instead, the texture coordinates [0, 1.0) reference the entire breadth of the array dimension; Note that for CUDA mipmapped arrays, this flag has to be set.
- CU_TRSF_DISABLE_TRILINEAR_OPTIMIZATION, which disables any trilinear filtering optimizations. Trilinear optimizations improve texture filtering performance by allowing bilinear filtering on textures in scenarios where it can closely approximate the expected results.
- CU_TRSF_SEAMLESS_CUBEMAP, which enables seamless cube map filtering. This flag can only be specified if the underlying resource is a CUDA array or a CUDA mipmapped array that was created with the flag CUDA_ARRAY3D_CUBEMAP. When seamless cube map filtering is enabled, texture address modes specified by CUDA_TEXTURE_DESC::addressMode are ignored. Instead, if the CUDA_TEXTURE_DESC::filterMode is set to CU_TR_FILTER_MODE_POINT the address mode CU_TR_ADDRESS_MODE_CLAMP will be applied for all dimensions. If the CUDA_TEXTURE_DESC::filterMode is set to CU_TR_FILTER_MODE_LINEAR seamless cube map filtering will be performed when sampling along the cube face borders.

CUDA_TEXTURE_DESC::maxAnisotropy specifies the maximum anisotropy ratio to be used when doing anisotropic filtering. This value will be clamped to the range [1,16].

CUDA_TEXTURE_DESC::mipmapFilterMode specifies the filter mode when the calculated mipmap level lies between two defined mipmap levels.

CUDA_TEXTURE_DESC::mipmapLevelBias specifies the offset to be applied to the calculated mipmap level.

CUDA_TEXTURE_DESC::minMipmapLevelClamp specifies the lower end of the mipmap level range to clamp access to.

CUDA_TEXTURE_DESC::maxMipmapLevelClamp specifies the upper end of the mipmap level range to clamp access to.

The CUDA_RESOURCE_VIEW_DESC struct is defined as

‎        typedef struct CUDA_RESOURCE_VIEW_DESC_st
              {
                  CUresourceViewFormat format;
                  size_t width;
                  size_t height;
                  size_t depth;
                  unsigned int firstMipmapLevel;
                  unsigned int lastMipmapLevel;
                  unsigned int firstLayer;
                  unsigned int lastLayer;
              } CUDA_RESOURCE_VIEW_DESC;

where:

CUDA_RESOURCE_VIEW_DESC::format specifies how the data contained in the CUDA array or CUDA mipmapped array should be interpreted. Note that this can incur a change in size of the texture data. If the resource view format is a block compressed format, then the underlying CUDA array or CUDA mipmapped array has to have a base of format CU_AD_FORMAT_UNSIGNED_INT32. with 2 or 4 channels, depending on the block compressed format. For ex., BC1 and BC4 require the underlying CUDA array to have a format of CU_AD_FORMAT_UNSIGNED_INT32 with 2 channels. The other BC formats require the underlying resource to have the same base format but with 4 channels.

CUDA_RESOURCE_VIEW_DESC::width specifies the new width of the texture data. If the resource view format is a block compressed format, this value has to be 4 times the original width of the resource. For non block compressed formats, this value has to be equal to that of the original resource.

CUDA_RESOURCE_VIEW_DESC::height specifies the new height of the texture data. If the resource view format is a block compressed format, this value has to be 4 times the original height of the resource. For non block compressed formats, this value has to be equal to that of the original resource.

CUDA_RESOURCE_VIEW_DESC::depth specifies the new depth of the texture data. This value has to be equal to that of the original resource.

CUDA_RESOURCE_VIEW_DESC::firstMipmapLevel specifies the most detailed mipmap level. This will be the new mipmap level zero. For non-mipmapped resources, this value has to be zero.CUDA_TEXTURE_DESC::minMipmapLevelClamp and CUDA_TEXTURE_DESC::maxMipmapLevelClamp will be relative to this value. For ex., if the firstMipmapLevel is set to 2, and a minMipmapLevelClamp of 1.2 is specified, then the actual minimum mipmap level clamp will be 3.2.

CUDA_RESOURCE_VIEW_DESC::lastMipmapLevel specifies the least detailed mipmap level. For non-mipmapped resources, this value has to be zero.

CUDA_RESOURCE_VIEW_DESC::firstLayer specifies the first layer index for layered textures. This will be the new layer zero. For non-layered resources, this value has to be zero.

CUDA_RESOURCE_VIEW_DESC::lastLayer specifies the last layer index for layered textures. For non-layered resources, this value has to be zero.

CUresult cuTexObjectDestroy ( CUtexObject texObject )

Destroys a texture object.

Parameters

texObject: - Texture object to destroy

Returns

CUDA_SUCCESS, CUDA_ERROR_DEINITIALIZED, CUDA_ERROR_NOT_INITIALIZED, CUDA_ERROR_INVALID_CONTEXT, CUDA_ERROR_INVALID_VALUE

Description

Destroys the texture object specified by texObject.

CUresult cuTexObjectGetResourceDesc ( CUDA_RESOURCE_DESC* pResDesc, CUtexObject texObject )

Returns a texture object's resource descriptor.

Parameters

pResDesc: - Resource descriptor
texObject: - Texture object

Returns

CUDA_SUCCESS, CUDA_ERROR_DEINITIALIZED, CUDA_ERROR_NOT_INITIALIZED, CUDA_ERROR_INVALID_CONTEXT, CUDA_ERROR_INVALID_VALUE

Description

Returns the resource descriptor for the texture object specified by texObject.

CUresult cuTexObjectGetResourceViewDesc ( CUDA_RESOURCE_VIEW_DESC* pResViewDesc, CUtexObject texObject )

Returns a texture object's resource view descriptor.

Parameters

pResViewDesc: - Resource view descriptor
texObject: - Texture object

Returns

CUDA_SUCCESS, CUDA_ERROR_DEINITIALIZED, CUDA_ERROR_NOT_INITIALIZED, CUDA_ERROR_INVALID_CONTEXT, CUDA_ERROR_INVALID_VALUE

Description

Returns the resource view descriptor for the texture object specified by texObject. If no resource view was set for texObject, the CUDA_ERROR_INVALID_VALUE is returned.

CUresult cuTexObjectGetTextureDesc ( CUDA_TEXTURE_DESC* pTexDesc, CUtexObject texObject )

Returns a texture object's texture descriptor.

Parameters

pTexDesc: - Texture descriptor
texObject: - Texture object

Returns

CUDA_SUCCESS, CUDA_ERROR_DEINITIALIZED, CUDA_ERROR_NOT_INITIALIZED, CUDA_ERROR_INVALID_CONTEXT, CUDA_ERROR_INVALID_VALUE

Description

Returns the texture descriptor for the texture object specified by texObject.