WEBGL_compressed_texture_s3tc extension

The WEBGL_compressed_texture_s3tc extension is part of the WebGL API and exposes four S3TC compressed texture formats.

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 {{domxref("WebGLRenderingContext.getExtension()")}} method. For more information, see also Using Extensions in the WebGL tutorial.

[!NOTE] This extension is available to both, {{domxref("WebGLRenderingContext", "WebGL1", "", 1)}} and {{domxref("WebGL2RenderingContext", "WebGL2", "", 1)}} contexts.

Constants

The compressed texture formats are exposed by four constants and can be used in two functions: {{domxref("WebGLRenderingContext.compressedTexImage2D", "compressedTexImage2D()")}} and {{domxref("WebGLRenderingContext.compressedTexSubImage2D", "compressedTexSubImage2D()")}}.

ext.COMPRESSED_RGB_S3TC_DXT1_EXT
- : A DXT1-compressed image in an RGB image format.
ext.COMPRESSED_RGBA_S3TC_DXT1_EXT
- : A DXT1-compressed image in an RGB image format with an on/off alpha value.
ext.COMPRESSED_RGBA_S3TC_DXT3_EXT
- : A DXT3-compressed image in an RGBA image format. Compared to a 32-bit RGBA texture, it offers 4:1 compression.
ext.COMPRESSED_RGBA_S3TC_DXT5_EXT
- : A DXT5-compressed image in an RGBA image format. It also provides a 4:1 compression, but differs to the DXT3 compression in how the alpha compression is done.

Examples

const ext =
  gl.getExtension("WEBGL_compressed_texture_s3tc") ||
  gl.getExtension("MOZ_WEBGL_compressed_texture_s3tc") ||
  gl.getExtension("WEBKIT_WEBGL_compressed_texture_s3tc");

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

gl.compressedTexImage2D(
  gl.TEXTURE_2D,
  0,
  ext.COMPRESSED_RGBA_S3TC_DXT5_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);

Constants

Examples

Specifications

Browser compatibility

See also