glCopyImageSubData may be used to copy data from one image (i.e. texture or renderbuffer) to another. glCopyImageSubData does not perform general-purpose conversions such as scaling, resizing, blending, color-space, or format conversions. It should be considered to operate in a manner similar to a CPU memcpy. CopyImageSubData can copy between images with different internal formats, provided the formats are compatible.
glCopyImageSubData also allows copying between certain types of compressed and uncompressed internal formats. This copy does not perform on-the-fly compression or decompression. When copying from an uncompressed internal format to a compressed internal format, each texel of uncompressed data becomes a single block of compressed data. When copying from a compressed internal format to an uncompressed internal format, a block of compressed data becomes a single texel of uncompressed data. The texel size of the uncompressed format must be the same size the block size of the compressed formats. Thus it is permitted to copy between a 128-bit uncompressed format and a compressed format which uses 8-bit 4x4 blocks, or between a 64-bit uncompressed format and a compressed format which uses 4-bit 4x4 blocks.
The source object is identified by srcName and srcTarget and the destination object is identified by dstName and dstTarget. The interpretation of the name depends on the value of the corresponding target parameter. If target is GL_RENDERBUFFER, the name is interpreted as the name of a renderbuffer object. If the target parameter is a texture target, the name is interpreted as a texture object. All non-proxy texture targets are accepted, with the exception of GL_TEXTURE_BUFFER and the cubemap face selectors.
srcLevel and dstLevel identify the source and destination level of detail. For textures, this must be a valid level of detail in the texture object. For renderbuffers, this value must be zero.
srcX, srcY, and srcZ specify the lower left texel coordinates of a srcWidth-wide by srcHeight-high by srcDepth-deep rectangular subregion of the source texel array. Similarly, dstX, dstY and dstZ specify the coordinates of a subregion of the destination texel array. The source and destination subregions must be contained entirely within the specified level of the corresponding image objects.
The dimensions are always specified in texels, even for compressed texture formats. However, it should be noted that if only one of the source and destination textures is compressed then the number of texels touched in the compressed image will be a factor of the block size larger than in the uncompressed image.
Slices of a GL_TEXTURE_1D_ARRAY, GL_TEXTURE_2D_ARRAY, GL_TEXTURE_CUBE_MAP_ARRAY GL_TEXTURE_3D and faces of GL_TEXTURE_CUBE_MAP are all compatible provided they share a compatible internal format, and multiple slices or faces may be copied between these objects with a single call by specifying the starting slice with srcZ and dstZ, and the number of slices to be copied with srcDepth. Cubemap textures always have six faces which are selected by a zero-based face index.
For the purposes of CopyImageSubData, two internal formats are considered compatible if any of the following conditions are met:
If the formats are not compatible, an INVALID_OPERATION error is generated.
Table 1. Sized Internal Formats
|Texel / Block Size||Uncompressed Internal Format||
Compressed Internal Format(s)
|64-bit||GL_RGBA32UI, GL_RGBA32I, GL_RGBA32F||
GL_INVALID_OPERATION is generated if the texel size of the uncompressed image is not equal to the block size of the compressed image.
GL_INVALID_ENUM is generated if either target parameter is not GL_RENDERBUFFER, a valid non-proxy texture target other than GL_TEXTURE_BUFFER, or is one of the cubemap face selectors.
GL_INVALID_ENUM is generated if target does not match the type of the object.
GL_INVALID_OPERATION is generated if either object is a texture and the texture is not complete.
GL_INVALID_OPERATION is generated if the source and destination internal formats are not compatible, or if the number of samples do not match.
GL_INVALID_VALUE is generated if either name does not correspond to a valid renderbuffer or texture object according to the corresponding target parameter.
GL_INVALID_VALUE is generated if the specified level of either the source or destination is not a valid level for the corresponding image.
GL_INVALID_VALUE is generated if the dimensions of the either subregion exceeds the boundaries of the corresponding image object, or if the image format is compressed and the dimensions of the subregion fail to meet the alignment constraints of the format.
|Function / Feature Name||2.0||2.1||3.0||3.1||3.2||3.3||4.0||4.1||4.2||4.3||4.4||
Copyright © 2013-2014 Khronos Group. This material may be distributed subject to the terms and conditions set forth in the Open Publication License, v 1.0, 8 June 1999. m[blue]http://opencontent.org/openpub/m.