WebGL OES_sample_variables Extension Specification

Name

OES_sample_variables

Contact

WebGL working group (public_webgl 'at' khronos.org)

Contributors

Members of the WebGL working group

Version

Last modified date: April 18, 2024
Revision: 2

Number

WebGL extension #56

Dependencies

Written against the WebGL API 2.0 specification.

Overview

This extension exposes the OES_sample_variables functionality to WebGL.

The following WebGL-specific behavioral changes apply:

• When a fragment shader writes to gl_SampleMask, implementations may implicitly disable SAMPLE_ALPHA_TO_COVERAGE state.

Consult the above extension for documentation, issues and new functions and enumerants.

When this extension is enabled:

• When a fragment shader enables, requires, or warns GL_OES_sample_variables with an #extension directive:
  • int gl_SampleMaskIn[] is a built-in input.
  • int gl_SampleID is a built-in input.
  • vec2 gl_SamplePosition is a built-in input.
  • int gl_SampleMask[] is a built-in output.
  • int gl_MaxSamples is a built-in constant.
  • int gl_NumSamples is a built-in uniform.
• The GLSL macro GL_OES_sample_variables is defined as 1.

IDL

[Exposed=(Window,Worker), LegacyNoInterfaceObject]
interface OES_sample_variables {
};
  

Revision History

Revision 1, 2023/06/01

• Initial Draft.

Revision 2, 2024/04/18

• Promoted to Community Approved.