EXT_texture_compression_rgtc extension

{{APIRef("WebGL")}}

The EXT_texture_compression_rgtc extension is part of the WebGL API and exposes 4 RGTC compressed texture formats. RGTC is a block-based texture compression format suited for unsigned and signed red and red-green textures (Red-Green Texture Compression).

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

[!NOTE] Support depends on the system's graphics driver. There is no support on Windows.

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

Constants

The compressed texture formats are exposed by 4 constants and can be used in two functions: {{domxref("WebGLRenderingContext.compressedTexImage2D", "compressedTexImage2D()")}} and {{domxref("WebGLRenderingContext.compressedTexSubImage2D", "compressedTexSubImage2D()")}}.

• ext.COMPRESSED_RED_RGTC1_EXT
  • : Each 4x4 block of texels consists of 64 bits of unsigned red image data. See also BC4 unsigned.
• ext.COMPRESSED_SIGNED_RED_RGTC1_EXT
  • : Each 4x4 block of texels consists of 64 bits of signed red image data. See also BC4 signed.
• ext.COMPRESSED_RED_GREEN_RGTC2_EXT
  • : Each 4x4 block of texels consists of 64 bits of compressed unsigned red image data followed by 64 bits of compressed unsigned green image data. See also BC5 unsigned.
• ext.COMPRESSED_SIGNED_RED_GREEN_RGTC2_EXT
  • : Each 4x4 block of texels consists of 64 bits of compressed signed red image data followed by 64 bits of compressed signed green image data. See also BC5 signed.

Examples

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

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

gl.compressedTexImage2D(
  gl.TEXTURE_2D,
  0,
  ext.COMPRESSED_RED_RGTC1_EXT,
  128,
  128,
  0,
  textureData,
);

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}

See also

• {{domxref("WebGLRenderingContext.getExtension()")}}
• {{domxref("WebGLRenderingContext.compressedTexImage2D()")}}
• {{domxref("WebGLRenderingContext.compressedTexSubImage2D()")}}
• {{domxref("WebGLRenderingContext.getParameter()")}}