WebGLRenderingContext.compressedTexSubImage2D()

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

Compressed image formats must be enabled by WebGL extensions before using this method or a WebGL2RenderingContext must be used.

Syntax

void gl.compressedTexSubImage2D(target, level, xoffset, yoffset, width, height, format, ArrayBufferView? pixels);

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 nth 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. Compressed image formats must be enabled by WebGL extensions before using this method. Possible values:

• When using the WEBGL_compressed_texture_s3tc extension:
  • ext.COMPRESSED_RGB_S3TC_DXT1_EXT
  • ext.COMPRESSED_RGBA_S3TC_DXT1_EXT
  • ext.COMPRESSED_RGBA_S3TC_DXT3_EXT
  • ext.COMPRESSED_RGBA_S3TC_DXT5_EXT
• When using the WEBGL_compressed_texture_es3 extension:
  • ext.COMPRESSED_R11_EAC
  • ext.COMPRESSED_SIGNED_R11_EAC
  • ext.COMPRESSED_RG11_EAC
  • ext.COMPRESSED_SIGNED_RG11_EAC
  • ext.COMPRESSED_RGB8_ETC2
  • ext.COMPRESSED_RGBA8_ETC2_EAC
  • ext.COMPRESSED_SRGB8_ETC2
  • ext.COMPRESSED_SRGB8_ALPHA8_ETC2_EAC
  • ext.COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2
  • ext.COMPRESSED_SRGB8_PUNCHTHROUGH_ALPHA1_ETC2
• When using the WEBGL_compressed_texture_pvrtc extension:
  • ext.COMPRESSED_RGB_PVRTC_4BPPV1_IMG
  • ext.COMPRESSED_RGBA_PVRTC_4BPPV1_IMG
  • ext.COMPRESSED_RGB_PVRTC_2BPPV1_IMG
  • ext.COMPRESSED_RGBA_PVRTC_2BPPV1_IMG
• When using the WEBGL_compressed_texture_atc extension:
  • ext.COMPRESSED_RGB_ATC_WEBGL
  • ext.COMPRESSED_RGBA_ATC_EXPLICIT_ALPHA_WEBGL
  • ext.COMPRESSED_RGBA_ATC_INTERPOLATED_ALPHA_WEBGL
• When using a WebGL 2 context, the following values are available:
  • gl.COMPRESSED_R11_EAC
  • gl.COMPRESSED_SIGNED_R11_EAC
  • gl.COMPRESSED_RG11_EAC
  • gl.COMPRESSED_SIGNED_RG11_EAC
  • gl.COMPRESSED_RGB8_ETC2
  • gl.COMPRESSED_RGBA8_ETC2_EAC
  • gl.COMPRESSED_SRGB8_ETC2
  • gl.COMPRESSED_SRGB8_ALPHA8_ETC2_EAC
  • gl.COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2
  • gl.COMPRESSED_SRGB8_PUNCHTHROUGH_ALPHA1_ETC2

pixels

A ArrayBufferView that be used as a data store for the compressed image data in memory.

Return value

None.

Examples

var 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

[1] WebGL 2 is enabled by default in Firefox Nightly. To enable it in a release version of Firefox, set the preference webgl.enable-prototype-webgl2 to true in about:config.

[2] To use an experimental implementation of WebGL 2 in Chrome, you have to start Chrome with the runtime flag --enable-unsafe-es3-apis.

See also

• Using WebGL extensions
• WebGLRenderingContext.getExtension()
• WebGLRenderingContext.compressedTexImage2D()
• WEBGL_compressed_texture_s3tc
• WEBGL_compressed_texture_es3
• WEBGL_compressed_texture_pvrtc
• WEBGL_compressed_texture_atc