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glCompressedTexSubImage2D

Name

glCompressedTexSubImage2D — specify a two-dimensional texture subimage in a compressed format

C Specification

void glCompressedTexSubImage2D( GLenum target,
  GLint level,
  GLint xoffset,
  GLint yoffset,
  GLsizei width,
  GLsizei height,
  GLenum format,
  GLsizei imageSize,
  const void * data);
 

Parameters

target

Specifies the target texture. Must be GL_TEXTURE_2D, GL_TEXTURE_CUBE_MAP_POSITIVE_X, GL_TEXTURE_CUBE_MAP_NEGATIVE_X, GL_TEXTURE_CUBE_MAP_POSITIVE_Y, GL_TEXTURE_CUBE_MAP_NEGATIVE_Y, GL_TEXTURE_CUBE_MAP_POSITIVE_Z, or GL_TEXTURE_CUBE_MAP_NEGATIVE_Z.

level

Specifies the level-of-detail number. Level 0 is the base image level. Level n is the nth mipmap reduction image.

xoffset

Specifies a texel offset in the x direction within the texture array.

yoffset

Specifies a texel offset in the y direction within the texture array.

width

Specifies the width of the texture subimage.

height

Specifies the height of the texture subimage.

format

Specifies the format of the compressed image data stored at address data.

imageSize

Specifies the number of unsigned bytes of image data starting at the address specified by data.

data

Specifies a pointer to the compressed image data in memory.

Description

Texturing allows elements of an image array to be read by shaders.

glCompressedTexSubImage2D redefines a contiguous subregion of an existing two-dimensional texture image. The texels referenced by data replace the portion of the existing texture array with x indices xoffset and xoffset + width - 1 , and the y indices yoffset and yoffset + height - 1 , inclusive. This region may not include any texels outside the range of the texture array as it was originally specified. It is not an error to specify a subtexture with width of 0, but such a specification has no effect.

format must be a known compressed image format from Table 1 below or an extension-specified compressed-texture format.

If a non-zero named buffer object is bound to the GL_PIXEL_UNPACK_BUFFER target (see glBindBuffer) while a texture image is specified, data is treated as a byte offset into the buffer object's data store.

Table 1. Compressed Internal Formats
Compressed Internal Format Base Internal Format Image Size
GL_COMPRESSED_R11_EAC GL_RED ceil(width/4) * ceil(height/4) * 8
GL_COMPRESSED_SIGNED_R11_EAC GL_RED ceil(width/4) * ceil(height/4) * 8
GL_COMPRESSED_RG11_EAC GL_RG ceil(width/4) * ceil(height/4) * 16
GL_COMPRESSED_SIGNED_RG11_EAC GL_RG ceil(width/4) * ceil(height/4) * 16
GL_COMPRESSED_RGB8_ETC2 GL_RGB ceil(width/4) * ceil(height/4) * 8
GL_COMPRESSED_SRGB8_ETC2 GL_RGB ceil(width/4) * ceil(height/4) * 8
GL_COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2 GL_RGBA ceil(width/4) * ceil(height/4) * 8
GL_COMPRESSED_SRGB8_PUNCHTHROUGH_ALPHA1_ETC2 GL_RGBA ceil(width/4) * ceil(height/4) * 8
GL_COMPRESSED_RGBA8_ETC2_EAC GL_RGBA ceil(width/4) * ceil(height/4) * 16
GL_COMPRESSED_SRGB8_ALPHA8_ETC2_EAC GL_RGBA ceil(width/4) * ceil(height/4) * 16
GL_COMPRESSED_RGBA_ASTC_4x4 GL_RGBA ceil(width/4) * ceil(height/4) * 16
GL_COMPRESSED_RGBA_ASTC_5x4 GL_RGBA ceil(width/5) * ceil(height/4) * 16
GL_COMPRESSED_RGBA_ASTC_5x5 GL_RGBA ceil(width/5) * ceil(height/5) * 16
GL_COMPRESSED_RGBA_ASTC_6x5 GL_RGBA ceil(width/6) * ceil(height/5) * 16
GL_COMPRESSED_RGBA_ASTC_6x6 GL_RGBA ceil(width/6) * ceil(height/6) * 16
GL_COMPRESSED_RGBA_ASTC_8x5 GL_RGBA ceil(width/8) * ceil(height/5) * 16
GL_COMPRESSED_RGBA_ASTC_8x6 GL_RGBA ceil(width/8) * ceil(height/6) * 16
GL_COMPRESSED_RGBA_ASTC_8x8 GL_RGBA ceil(width/8) * ceil(height/8) * 16
GL_COMPRESSED_RGBA_ASTC_10x5 GL_RGBA ceil(width/10) * ceil(height/5) * 16
GL_COMPRESSED_RGBA_ASTC_10x6 GL_RGBA ceil(width/10) * ceil(height/6) * 16
GL_COMPRESSED_RGBA_ASTC_10x8 GL_RGBA ceil(width/10) * ceil(height/8) * 16
GL_COMPRESSED_RGBA_ASTC_10x10 GL_RGBA ceil(width/10) * ceil(height/10) * 16
GL_COMPRESSED_RGBA_ASTC_12x10 GL_RGBA ceil(width/12) * ceil(height/10) * 16
GL_COMPRESSED_RGBA_ASTC_12x12 GL_RGBA ceil(width/12) * ceil(height/12) * 16
GL_COMPRESSED_SRGB8_ALPHA8_ASTC_4x4 GL_RGBA ceil(width/4) * ceil(height/4) * 16
GL_COMPRESSED_SRGB8_ALPHA8_ASTC_5x4 GL_RGBA ceil(width/5) * ceil(height/4) * 16
GL_COMPRESSED_SRGB8_ALPHA8_ASTC_5x5 GL_RGBA ceil(width/5) * ceil(height/5) * 16
GL_COMPRESSED_SRGB8_ALPHA8_ASTC_6x5 GL_RGBA ceil(width/6) * ceil(height/5) * 16
GL_COMPRESSED_SRGB8_ALPHA8_ASTC_6x6 GL_RGBA ceil(width/6) * ceil(height/6) * 16
GL_COMPRESSED_SRGB8_ALPHA8_ASTC_8x5 GL_RGBA ceil(width/8) * ceil(height/5) * 16
GL_COMPRESSED_SRGB8_ALPHA8_ASTC_8x6 GL_RGBA ceil(width/8) * ceil(height/6) * 16
GL_COMPRESSED_SRGB8_ALPHA8_ASTC_8x8 GL_RGBA ceil(width/8) * ceil(height/8) * 16
GL_COMPRESSED_SRGB8_ALPHA8_ASTC_10x5 GL_RGBA ceil(width/10) * ceil(height/5) * 16
GL_COMPRESSED_SRGB8_ALPHA8_ASTC_10x6 GL_RGBA ceil(width/10) * ceil(height/6) * 16
GL_COMPRESSED_SRGB8_ALPHA8_ASTC_10x8 GL_RGBA ceil(width/10) * ceil(height/8) * 16
GL_COMPRESSED_SRGB8_ALPHA8_ASTC_10x10 GL_RGBA ceil(width/10) * ceil(height/10) * 16
GL_COMPRESSED_SRGB8_ALPHA8_ASTC_12x10 GL_RGBA ceil(width/12) * ceil(height/10) * 16
GL_COMPRESSED_SRGB8_ALPHA8_ASTC_12x12 GL_RGBA ceil(width/12) * ceil(height/12) * 16


Errors

GL_INVALID_ENUM is generated if format is not one of the specific compressed internal formats listed in Table 1 above.

GL_INVALID_VALUE is generated if imageSize is not consistent with the format, dimensions, and contents of the specified compressed image data.

GL_INVALID_OPERATION is generated if parameter combinations are not supported by the specific compressed internal format as specified in the specific texture compression extension.

For ETC2/EAC images GL_INVALID_OPERATION is generated if width is not a multiple of four, and width + xoffset is not equal to the width of the texture level; if height is not a multiple of four, and height + yoffset is not equal to the height of the texture level; or if xoffset or yoffset is not a multiple of four.

For ASTC images GL_INVALID_OPERATION is generated if width is not a multiple of the block width, and width + xoffset is not equal to the width of the texture level; if height is not a multiple of the block height, and height + yoffset is not equal to the height of the texture level; or if xoffset or yoffset is not a multiple of the corresponding block dimension.

GL_INVALID_OPERATION is generated if a non-zero buffer object name is bound to the GL_PIXEL_UNPACK_BUFFER target and the buffer object's data store is currently mapped.

GL_INVALID_OPERATION is generated if a non-zero buffer object name is bound to the GL_PIXEL_UNPACK_BUFFER target and the data would be unpacked from the buffer object such that the memory reads required would exceed the data store size.

Undefined results, including abnormal program termination, are generated if data is not encoded in a manner consistent with the extension specification defining the internal compression format.

Associated Gets

glGet with argument GL_PIXEL_UNPACK_BUFFER_BINDING

API Version Support

OpenGL ES API Version
Function Name 2.0 3.0 3.1 3.2
glCompressedTexSubImage2D ✔ ✔ ✔ ✔
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