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Name
EXT_color_buffer_float
Name Strings
GL_EXT_color_buffer_float
Contributors
OpenGL ES Working Group members
Contact
Mark Callow, HI Corp. (callow.mark 'at' artspark.co.jp)
Notice
©2012 The Khronos Group Inc.
Status
Complete
IP Status
Graphics Properties Holdings (GPH, formerly SGI) owns US Patent
#6,650,327, issued November 18, 2003. GPH believes this patent
contains necessary IP for graphics systems implementing floating
point (FP) rasterization and FP framebuffer capabilities.
GPH will not grant Khronos royalty-free use of this IP for use
in OpenGL ES, but will discuss licensing on RAND terms, on an
individual basis with companies wishing to use this IP in the
context of conformant OpenGL ES implementations. GPH does not
plan to make any special exemption for open source
implementations.
See
https://www.khronos.org/files/ip-disclosures/opengl/SGI%20IP%20Disclosure%20Mar05_clean.pdf
for the full disclosure.
Version
Date: January 11th, 2013
Revision: 5
Number
OpenGL ES Extension #137
Dependencies
Requires OpenGL ES 3.0.
Written based on the wording of the OpenGL ES 3.0.1 Specification
(January 10th, 2013).
Overview
This extension allows a variety of floating point formats to be
rendered to via framebuffer objects.
New Procedures and Functions
None
New Tokens
None
Additions to Chapter 3 of the OpenGL ES 3.0 Specification
(Rasterization)
3.8.3 Texture Image Specification, unnumbered subsection "Required
Texture Formats", p. 126
Change the first two bullet items to the following:
- Texture and renderbuffer color formats (see section 4.4.2).
- RGBA32F, RGBA32I, RGBA32UI, RGBA16F, RGBA16I, RGBA16UI,
RGBA8, RGBA8I, RGBA8UI, SRGB8_ALPHA8, RGB10_A2, RGB10_-
A2UI, RGBA4, and RGB5_A1.
- RGB8 and RGB565.
- R11F G11F B10F.
- RG32F, RG32I, RG32UI, RG16F, RG16I, RG16UI, RG8, RG8I, and
RG8UI.
- R32F, R32I, R32UI, R16F, R16I, R16UI, R8, R8I, and R8UI.
- Texture-only color formats:
- RGBA8_SNORM.
- RGB32F, RGB32I, and RGB32UI.
- RGB16F, RGB16I, and RGB16UI.
- RGB8_SNORM, RGB8I, RGB8UI, and SRGB8.
- RGB9_E5.
- RG8_SNORM.
- R8_SNORM.
Table 3.12, p. 128 & 129
Convert the dash under 'Color-renderable' to a 'check' for the
following internal formats: R16F, RG16F, RGBA16F, R32F, RG32F,
RGBA32F and R11F_G11F_B10F.
Additions to Chapter 4 of the OpenGL ES 3.0 Specification (Per-Fragment
Operations and the Framebuffer)
(changed lines marked with *; added lines marked with +)
Chapter 4 Introduction, p. 167
Paragraph 5, sentence 3, p 168, insert "floating point" as shown:
"R, G, B, and A components may be represented as unsigned
* normalized fixed-point, floating point or signed or unsigned
integer values; ..." ^^^^^^^^^^^^^^
4.1.7 Blending, p. 174
Modify paragraphs 3 & 4:
* "If the color buffer is fixed-point, the components of the
source and destination values and blend factors are clamped
* to [0; 1] prior to evaluating the blend equation. If the color
+ buffer is floating-point, no clamping occurs. The resulting four
+ values are sent to the next operation.
Blending applies only if the color buffer has a fixed-point or
* or floating-point format. If the color buffer has an integer
* format, proceed to the next operation. Furthermore, an
+ INVALID_OPERATION error is generated by DrawArrays and the other
+ drawing commands defined in section 2.8.3 if blending is enabled
+ (see below) and any draw buffer has a 32-bit floating-point
+ format."
4.2.3 Clearing the Buffers, p. 183
Modify second paragraph, inserting "floating point":
" void ClearColor(float r, float g, float b, float a);
* sets the clear value for fixed- and floating-point color buffers.
..." ^^^^^^^^^^^^^^^^^^
4.3.1 Reading Pixels, p. 186
In paragraph 4, beginning "Only two combinations of format
and type are accepted ...", after the sentence ending "... type
UNSIGNED_BYTE is accepted." insert the following sentence:
"For floating-point rendering surfaces, the combination
format RGBA and type FLOAT is accepted."
4.3.1 unnumbered subsection "Obtaining Pixels from the Framebuffer",
p. 188
Modify penultimate paragraph, p189, "If format is an integer ..."
"If format is an integer format and the color buffer is not an
integer format; if the color buffer is an integer format and
* format is not an integer format; if format is an integer format
* and type is FLOAT, HALF_FLOAT, or UNSIGNED_INT_10F_11F_11F_REV;
+ or if the color buffer is a floating-point format and type is
+ not FLOAT, HALF FLOAT, or UNSIGNED_INT_10F_11F_11F_REV, the error
INVALID_OPERATION occurs."
4.3.1 unnumbered subsection "Conversion of RGBA values", p.190
Sole paragraph, sentence 3, insert "or floating point" as shown:
* "For an integer or floating point color buffer, the elements
are unmodified."^^^^^^^^^^^^^^^^^
4.3.2 Copying Pixels, p192
Modify first error condition, at bottom of p193, "The read buffer
contains ..." to encompass floating-point buffers.
* "- The read buffer contains fixed-point or floating-point values
* and any draw buffer contains neither fixed-point nor
* floating-point values."
4.4.2 Attaching Images to Framebuffer Objects, p. 197, unnumbered
subsection "Required Renderbuffer Formats", p. 200
In the last paragraph beginning "Implementations must support
creation ...", modify the final phrase to
* "with the exception of signed and unsigned integer, RGBA16F,
+ R32F, RG32F and RGBA32F formats.
Additions to Chapter 5 of the OpenGL ES 2.0 Specification (Special Functions)
None
Additions to Chapter 6 of the OpenGL ES 2.0 Specification (State and State
Requests)
6.1.15 Internal Format Queries, p. 237
P. 238, paragraph 8 after "Since multisampling is not supported
for signed and unsigned integer internal formats, the value of
NUM_SAMPLE_COUNTS will be zero for such formats.", insert new
one-sentence paragraph:
"If <internalformat> is RGBA16F, R32F, RG32F, or RGBA32F, the
value of NUM_SAMPLE_COUNTS may be zero, or else the maximum
value in SAMPLES may be less than the value of MAX_SAMPLES."
New Implementation Dependent State
None
Issues
Revision History
Rev. Date Author Changes
---- -------- --------- -----------------------------------------
1 10/16/12 markc Initial version
2 10/18/12 markc Referenced preliminary version of OpenGL
ES 3.0.1 specification and updated page
numbers.
3 11/21/12 markc Corrected IP status.
4 01/09/13 markc Changed date of referenced OpenGL ES
3.0.1 specification. Made minor language
simplification.
5 01/11/13 markc Changed date to release version of
OpenGL ES 3.0.1 specification.
Clarified change to "Required
renderbuffer formats" section.
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