WebGL WEBGL_color_buffer_float Extension Draft 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: November 26, 2012
Revision: 4

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.

Overview

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

When this extension is enabled:

• The 32-bit floating-point types RGB32F and RGBA32F become available as color-renderable formats. Renderbuffers can be created in these formats. These and textures created with type = FLOAT, which will have one of these internal formats, can be attached to framebuffer object color attachments for rendering.

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

• 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

module webgl {
  interface EXT_color_buffer_float {
    const GLenum RGBA32F_EXT = 0x8814;
    const GLenum RGB32F_EXT = 0x8815;
    const GLenum FRAMEBUFFER_ATTACHMENT_COMPONENT_TYPE_EXT = 0x8211;
    const GLenum UNSIGNED_NORMALIZED_EXT = 0x8C17;
  }; // interface EXT_color_buffer_float
}; // module webgl

New Tokens

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

RGBA32F_EXT and RGB32F_EXT are accepted as the internalformat parameter of renderbufferStorage().

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. All references to these are replaced by the 32-bit floating-point types specified above.

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.