GLCOMPRESSEDTEXSUBIM(3G)

🌸 NAME 🌸

okay so bestie, welcome to the [FIXME: manual] page for GLCOMPRESSEDTEXSUBIM(3G) — this is the whole vibe. glCompressedTexSubImage2D and glCompressedTextureSubImage2D specify a two-dimensional texture subimage in a compressed format. periodt. 💅

✨ C SPECIFICATION ✨

here's the exact signature, no cap:

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

       void glCompressedTextureSubImage2D(GLuint texture, GLint level,
                                          GLint xoffset, GLint yoffset,
                                          GLsizei width, GLsizei height,
                                          GLenum format, GLsizei imageSize,
                                          const void *data);

💖 PARAMETERS 💖

• target — for glCompressedTexSubImage2D, this is the target the texture is bound to. it must be GL_TEXTURE_1D_ARRAY, 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. yes, all of those, bestie ✨
• texture — the texture object name for glCompressedTextureSubImage2D.
• level — the level-of-detail number. level 0 is the base image level. level n is the *n*th mipmap reduction image.
• xoffset — a texel offset in the x direction within the texture array.
• yoffset — a texel offset in the y direction within the texture array.
• width — the width of the texture subimage.
• height — the height of the texture subimage.
• format — the format of the compressed image data stored at address data.
• imageSize — the number of unsigned bytes of image data starting at the address specified by data.
• data — a pointer to the compressed image data in memory.

🦋 DESCRIPTION 🦋

texturing allows elements of an image array to be read by shaders. iconic behavior, honestly.

glCompressedTexSubImage2D and glCompressedTextureSubImage2D redefine 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. also! it is not an error to specify a subtexture with width of 0, but such a specification has no effect. so like, valid but pointless. we've all been there 💀

internalformat must be a known compressed image format (such as GL_RGTC) or an extension-specified compressed-texture format. the format of the compressed texture image is selected by the GL implementation that compressed it (see glTexImage2D()) and should be queried at the time the texture was compressed with glGetTexLevelParameter().

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. okay? okay. 🫶

💀 ERRORS 💀

• GL_INVALID_ENUM is generated if internalformat is one of the generic compressed internal formats: GL_COMPRESSED_RED, GL_COMPRESSED_RG, GL_COMPRESSED_RGB, GL_COMPRESSED_RGBA, GL_COMPRESSED_SRGB, or GL_COMPRESSED_SRGB_ALPHA.
• GL_INVALID_ENUM is generated by glCompressedTexSubImage2D if target is GL_TEXTURE_RECTANGLE or GL_PROXY_TEXTURE_RECTANGLE.
• 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.
• 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.
• GL_INVALID_OPERATION is generated by glCompressedTextureSubImage2D if texture is not the name of an existing texture object.
• GL_INVALID_OPERATION is generated by glCompressedTextureSubImage2D if the effective target is GL_TEXTURE_RECTANGLE.

⚠️ warning bestie: 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. so pls encode responsibly 😭💀

🎀 ASSOCIATED GETS 🎀

• glGetCompressedTexImage()
• glGet() with argument GL_TEXTURE_COMPRESSED
• glGet() with argument GL_PIXEL_UNPACK_BUFFER_BINDING
• glGetTexLevelParameter() with arguments GL_TEXTURE_INTERNAL_FORMAT and GL_TEXTURE_COMPRESSED_IMAGE_SIZE

👑 VERSION SUPPORT 👑

the original table tracks Function / Feature Name across OpenGL Version 2.0, 2.1, 3.0, 3.1, 3.2, 3.3, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5. here's the vibe:

• glCompressedTexSubImage2D — ✔ in 2.0, 2.1, 3.0, 3.1, 3.2, 3.3, 4.0, 4.1, 4.2, 4.3, 4.4, and 4.5. slay, all of them 🔥
• glCompressedTextureSubImage2D — - in 2.0, 2.1, 3.0, 3.1, 3.2, 3.3, 4.0, 4.1, 4.2, 4.3, and 4.4; ✔ in 4.5 only. late bloomer icon behavior 👑

🌈 SEE ALSO 🌈

glActiveTexture(), glCompressedTexImage1D(), glCompressedTexImage2D(), glCompressedTexImage3D(), glCompressedTexSubImage1D(), glCompressedTexSubImage3D(), glCopyTexImage1D(), glCopyTexImage2D(), glCopyTexSubImage1D(), glCopyTexSubImage2D(), glCopyTexSubImage3D(), glPixelStore(), glTexImage2D(), glTexImage3D(), glTexSubImage1D(), glTexSubImage2D(), glTexSubImage3D(), glTexParameter()

📜 COPYRIGHT 📜

Copyright © 1991-2006 Silicon Graphics, Inc. Copyright © 2010-2014 Khronos Group. This document is licensed under the SGI Free Software B License. For details, see http://oss.sgi.com/projects/FreeB/.

📜 COPYRIGHT 📜

Copyright © 1991-2006 Silicon Graphics, Inc. Copyright © 2010-2014 Khronos Group

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okay bye bestie — this page is from [FIXME: source], dated 08/09/2021, and it's GLCOMPRESSEDTEXSUBIM(3G) forever 💅✨