WebGLRenderingContext: compressedTexSubImage2D() method

{{APIRef("WebGL")}}{{AvailableInWorkers}}

The compressedTexSubImage2D() method of the {{domxref("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 {{domxref("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 {{domxref("WebGL_API/Types", "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 {{domxref("WebGL_API/Types", "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 {{domxref("WebGL_API/Types", "GLint")}} specifying the horizontal offset within the compressed texture image.
• yoffset
  • : A {{domxref("WebGL_API/Types", "GLint")}} specifying the vertical offset within the compressed texture image.
• width
  • : A {{domxref("WebGL_API/Types", "GLsizei")}} specifying the width of the compressed texture.
• height
  • : A {{domxref("WebGL_API/Types", "GLsizei")}} specifying the height of the compressed texture.
• format
  • : A {{domxref("WebGL_API/Types", "GLenum")}} specifying the compressed image format. For a list of possible values, see {{domxref("WebGLRenderingContext.compressedTexImage2D()")}}.

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

• srcData
  • : A {{jsxref("TypedArray")}} or {{jsxref("DataView")}} containing the compressed texture data.
• srcOffset {{optional_inline}}
  • : (WebGL 2 only) An integer specifying the index of srcData to start reading from. Defaults to 0.
• srcLengthOverride {{optional_inline}}
  • : (WebGL 2 only) An integer specifying the number of elements in srcData to read. Defaults to srcData.length - srcOffset.
• imageSize
  • : (WebGL 2 only) A {{domxref("WebGL_API/Types", "GLsizei")}} specifying the size of the image data in bytes.
• offset
  • : (WebGL 2 only) A {{domxref("WebGL_API/Types", "GLintptr")}} specifying the starting address in the buffer bound to gl.PIXEL_UNPACK_BUFFER.

Return value

None ({{jsxref("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

{{Specifications}}

Browser compatibility

{{Compat}}

See also

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