WebGL WEBGL_color_buffer_float Extension Specification

Name

WEBGL_color_buffer_float

Contact

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

Contributors

Mark Callow, HI Corporation

Members of the WebGL working group

Version

Last modified date: December 02, 2022
Revision: 11

Number

WebGL extension #15

Dependencies

Written against the WebGL API 1.0 specification.

Written against the EXT_color_buffer_half_float specification.

Implementations must also support the OES_texture_float extension.

No longer available as of the WebGL API 2.0 specification. Subsumed by the EXT_color_buffer_float extension.

Overview

Adds support for rendering to 32-bit floating-point color buffers.

When this extension is enabled:

• The 32-bit floating-point type RGBA32F becomes available as a color-renderable format. Renderbuffers can be created in this format. These and textures created with format = RGBA and type = FLOAT as specified in OES_texture_float, can be attached to framebuffer object color attachments for rendering.

• The 32-bit floating-point type RGB32F may also optionally become available as a color-renderable format. These and textures created with format = RGB and type = FLOAT as specified in OES_texture_float, can be attached to framebuffer object color attachments for rendering. Applications must check framebuffer completeness to determine if an implementation actually supports this format.

• NOTE: fragment shaders outputs gl_FragColor and gl_FragData[0] will only be clamped and converted when the color buffer is fixed-point and clearColor() will no longer clamp its parameter values on input. Clamping will be applied as necessary at draw time according to the type of color buffer in use.

• If the implementation supports unclamped blend color, the blendColor() will no longer clamp its parameter values on input. Clamping will be applied as necessary at draw time according to the type of color buffer in use. Applications may check the effective blend color with getParameter.

• The format and type combination RGBA and FLOAT becomes valid for reading from a floating-point rendering buffer. Note: RGBA and UNSIGNED_BYTE cannot be used for reading from a floating-point rendering buffer.

• The component types of framebuffer object attachments can be queried.

IDL

[Exposed=(Window,Worker), LegacyNoInterfaceObject]
interface WEBGL_color_buffer_float {
  const GLenum RGBA32F_EXT = 0x8814;
  const GLenum FRAMEBUFFER_ATTACHMENT_COMPONENT_TYPE_EXT = 0x8211;
  const GLenum UNSIGNED_NORMALIZED_EXT = 0x8C17;
}; // interface WEBGL_color_buffer_float
  

New Tokens

undefined renderbufferStorage(GLenum target, GLenum internalformat, GLsizei width, GLsizei height)

RGBA32F_EXT is accepted as the internalformat parameter.

any getFramebufferAttachmentParameter(GLenum target, GLenum attachment, GLenum pname)

FRAMEBUFFER_ATTACHMENT_COMPONENT_TYPE_EXT is accepted as the pname parameter.

An INVALID_OPERATION error is generated if attachment is DEPTH_STENCIL_ATTACHMENT and pname is FRAMEBUFFER_ATTACHMENT_COMPONENT_TYPE_EXT.

Additions to the WebGL Specification

The new tokens and the behavioral changes for floating-point color buffers specified in EXT_color_buffer_half_float are incorporated into WebGL except for the RGB16F and RGBA16F types. References to RGB16F are ignored, and references to RGBA16F are replaced by references to RGBA32F.

Revision History

Revision 1, 2012/11/08

• Initial revision.

Revision 2, 2012/11/12

• Don't mirror EXT_color_buffer_half_float. Mirror has a different meaning from what is done here.

Revision 3, 2012/11/13

• Add reading-pixels-as-FLOAT feature to the Overview.

Revision 4, 2012/11/26

• Move to draft.

Revision 5, 2014/07/15

• Removed webgl module. Added NoInterfaceObject extended attribute.

Revision 6, 2014/09/11

• Fixed the name of the interface from EXT_color_buffer_float to WEBGL_color_buffer_float.

Revision 7, 2014/11/24

• Removed the support for RGB32F, since it is not natively supported on all platforms where WebGL is implemented.

Revision 8, 2014/11/24

• Move to community approved.

Revision 9, 2016/05/05

• Subsumed in WebGL 2.0 by EXT_color_buffer_float.

Revision 10, 2017/09/14

• Add optional RGB renderability.

Revision 11, 2022/12/02

• Clarified framebuffer object attachment component type queries.