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docs.GL

glCompressedTexImage2D

Name

glCompressedTexImage2D — specify a two-dimensional texture image in a compressed format

C Specification

void glCompressedTexImage2D( GLenum target,
GLint level,
GLenum internalformat,
GLsizei width,
GLsizei height,
GLint border,
GLsizei imageSize,
const GLvoid * 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.

internalformat

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

width

Specifies the width of the texture image. All implementations support 2D and cube-mapped texture images that are at least 2048 texels wide.

height

Specifies the height of the texture image. All implementations support 2D and cube-mapped texture images that are at least 2048 texels high.

border

This value must be 0.

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.

glCompressedTexImage2D loads a previously defined, and retrieved, compressed two-dimensional texture image if target is GL_TEXTURE_2D, or one of the cube map faces such as GL_TEXTURE_CUBE_MAP_POSITIVE_X. (see glTexImage2D).

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

imageSize must be appropriate for the width, height and depth of the internalformat specified. The size for an ETC/EAC image is given in Table 1 below.

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


Errors

GL_INVALID_ENUM is generated if internalformat is not one of the specific compressed internal formats: GL_COMPRESSED_R11_EAC, GL_COMPRESSED_SIGNED_R11_EAC, GL_COMPRESSED_RG11_EAC, GL_COMPRESSED_SIGNED_RG11_EAC, GL_COMPRESSED_RGB8_ETC2, GL_COMPRESSED_SRGB8_ETC2, GL_COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2, GL_COMPRESSED_SRGB8_PUNCHTHROUGH_ALPHA1_ETC2, GL_COMPRESSED_RGBA8_ETC2_EAC, or GL_COMPRESSED_SRGB8_ALPHA8_ETC2_EAC.

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

GL_INVALID_VALUE is generated if border is not 0.

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.

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
glCompressedTexImage2D ✔ ✔ ✔
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