OES_standard_derivatives

The OES_standard_derivatives extension is part of the WebGL API and adds the GLSL derivative functions dFdx, dFdy, and fwidth.

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

Availability: This extension is only available to WebGL1 contexts. In WebGL2, the functionality of this extension is available on the WebGL2 context by default. In WebGL 2, the constant is available as gl.FRAGMENT_SHADER_DERIVATIVE_HINT and it requires GLSL #version 300 es.

Constants

This extension exposes one new constant, which can be used in the hint() and getParameter() methods.

ext.FRAGMENT_SHADER_DERIVATIVE_HINT_OES
A Glenum indicating the accuracy of the derivative calculation for the GLSL built-in functions: dFdx, dFdy, and fwidth.

GLSL built-in functions

The following new functions can be used in GLSL shader code, if this extension is enabled:

genType dFdx(genType)
genType dFdy(genType)
genType fwidth(genType)

Examples

Enabling the extensions:

gl.getExtension("OES_standard_derivatives");
gl.getExtension("EXT_shader_texture_lod");

Shader code that avoids artifacts when wrapping texture coordinates:

<script type="x-shader/x-fragment">
#extension GL_EXT_shader_texture_lod : enable
#extension GL_OES_standard_derivatives : enable

uniform sampler2D myTexture;
varying vec2 texcoord;

void main(){
  gl_FragColor = texture2DGradEXT(myTexture, mod(texcoord, vec2(0.1, 0.5)), 
                                  dFdx(texcoord), dFdy(texcoord));
}
</script>

Specifications

Specification Status Comment
OES_standard_derivatives
The definition of 'OES_standard_derivatives' in that specification.
Recommendation Initial definition.

Browser compatibility

Feature Chrome Edge Firefox Internet Explorer Opera Safari Servo
Basic Support??10.0????
Feature Android Chrome for Android Edge Mobile Firefox for Android IE Mobile Opera Mobile Safari Mobile
Basic Support???????

See also

Document Tags and Contributors

 Contributors to this page: teoli, fscholz
 Last updated by: teoli,