WEBGL_compressed_texture_s3tc_srgb extension

The WEBGL_compressed_texture_s3tc_srgb extension is part of the WebGL API and exposes four S3TC compressed texture formats for the sRGB colorspace.

Compressed textures reduce the amount of memory needed to store a texture on the GPU, allowing for higher resolution textures or more of the same resolution textures.

WebGL extensions are available using the WebGLRenderingContext.getExtension() method. For more information, see also Using Extensions in the WebGL tutorial.

Constants

The compressed texture formats are exposed by four constants and can be used in two functions: compressedTexImage2D() and compressedTexSubImage2D().

ext.COMPRESSED_SRGB_S3TC_DXT1_EXT

A DXT1-compressed image in an sRGB image format.

ext.COMPRESSED_SRGB_ALPHA_S3TC_DXT1_EXT

A DXT1-compressed image in an sRGB image format with an on/off alpha value.

ext.COMPRESSED_SRGB_ALPHA_S3TC_DXT3_EXT

A DXT3-compressed image in an sRGBA image format.

ext.COMPRESSED_SRGB_ALPHA_S3TC_DXT5_EXT

A DXT5-compressed image in an sRGBA image format.

Examples

const ext = gl.getExtension("WEBGL_compressed_texture_s3tc_srgb");

const texture = gl.createTexture();
gl.bindTexture(gl.TEXTURE_2D, texture);

gl.compressedTexImage2D(
  gl.TEXTURE_2D,
  0,
  ext.COMPRESSED_SRGB_S3TC_DXT1_EXT,
  512,
  512,
  0,
  textureData,
);

gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);

Specifications

Browser compatibility

See also

• S3 Texture Compression – OpenGL wiki
• WebGLRenderingContext.getExtension()
• WebGLRenderingContext.compressedTexImage2D()
• WebGLRenderingContext.compressedTexSubImage2D()
• WebGLRenderingContext.getParameter()