WebGLRenderingContext: compressedTexSubImage2D() method

The compressedTexSubImage2D() method of the WebGLRenderingContext interface of the WebGL API specifies a two-dimensional sub-rectangle for a texture image in a compressed format.

Compressed image formats are only available via the WebGL2RenderingContext or some WebGL extension.

Syntax

// WebGL 1:
compressedTexSubImage2D(target, level, xoffset, yoffset, width, height, format, srcData)

// Additionally available in WebGL 2:
compressedTexSubImage2D(target, level, xoffset, yoffset, width, height, format, srcData, srcOffset)
compressedTexSubImage2D(target, level, xoffset, yoffset, width, height, format, srcData, srcOffset, srcLengthOverride)
compressedTexSubImage2D(target, level, xoffset, yoffset, width, height, format, imageSize, offset)

Parameters

target

A GLenum specifying the binding point (target) of the active compressed texture. Possible values:

• gl.TEXTURE_2D: A two-dimensional texture.
• gl.TEXTURE_CUBE_MAP_POSITIVE_X: Positive X face for a cube-mapped texture.
• gl.TEXTURE_CUBE_MAP_NEGATIVE_X: Negative X face for a cube-mapped texture.
• gl.TEXTURE_CUBE_MAP_POSITIVE_Y: Positive Y face for a cube-mapped texture.
• gl.TEXTURE_CUBE_MAP_NEGATIVE_Y: Negative Y face for a cube-mapped texture.
• gl.TEXTURE_CUBE_MAP_POSITIVE_Z: Positive Z face for a cube-mapped texture.
• gl.TEXTURE_CUBE_MAP_NEGATIVE_Z: Negative Z face for a cube-mapped texture.

level

A GLint specifying the level of detail. Level 0 is the base image level and level n is the n-th mipmap reduction level.

xoffset

A GLint specifying the horizontal offset within the compressed texture image.

yoffset

A GLint specifying the vertical offset within the compressed texture image.

width

A GLsizei specifying the width of the compressed texture.

height

A GLsizei specifying the height of the compressed texture.

format

A GLenum specifying the compressed image format. For a list of possible values, see WebGLRenderingContext.compressedTexImage2D().

The texture source can be provided in one of two ways: from an ArrayBuffer (possibly shared) using srcData, srcOffset, and srcLengthOverride; or, in WebGL 2, from gl.PIXEL_UNPACK_BUFFER using imageSize and offset.

srcData

A TypedArray or DataView containing the compressed texture data.

srcOffset Optional

(WebGL 2 only) An integer specifying the index of srcData to start reading from. Defaults to 0.

srcLengthOverride Optional

(WebGL 2 only) An integer specifying the number of elements in srcData to read. Defaults to srcData.length - srcOffset.

imageSize

(WebGL 2 only) A GLsizei specifying the size of the image data in bytes.

offset

(WebGL 2 only) A GLintptr specifying the starting address in the buffer bound to gl.PIXEL_UNPACK_BUFFER.

Return value

None (undefined).

Examples

const ext =
  gl.getExtension("WEBGL_compressed_texture_s3tc") ||
  gl.getExtension("MOZ_WEBGL_compressed_texture_s3tc") ||
  gl.getExtension("WEBKIT_WEBGL_compressed_texture_s3tc");
gl.compressedTexSubImage2D(
  gl.TEXTURE_2D,
  0,
  256,
  256,
  512,
  512,
  ext.COMPRESSED_RGBA_S3TC_DXT5_EXT,
  textureData,
);

Specifications

Browser compatibility

See also

• Using WebGL extensions
• WebGLRenderingContext.getExtension()
• WebGLRenderingContext.compressedTexImage2D()
• WebGL2RenderingContext.compressedTexSubImage3D()
• WebGL2RenderingContext.compressedTexImage3D()
• WEBGL_compressed_texture_s3tc
• WEBGL_compressed_texture_s3tc_srgb
• WEBGL_compressed_texture_etc
• WEBGL_compressed_texture_pvrtc
• WEBGL_compressed_texture_astc
• EXT_texture_compression_bptc
• EXT_texture_compression_rgtc