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Name
NV_coverage_sample_resolve
Name Strings
EGL_NV_coverage_sample_resolve
Contact
James Jones, NVIDIA Corporation (jajones 'at' nvidia.com)
Notice
Copyright NVIDIA Corporation, 2011
Status
NVIDIA Proprietary
Version
Last Modified Date: 2011/04/13
NVIDIA Revision: 1.0
Number
EGL Extension #30
Dependencies
Written based on the wording of the EGL 1.4 specification.
Trivially interacts with EGL_NV_coverage_sample
Requires EGL 1.2.
Overview
NV_coverage_sample introduced a method to improve rendering quality
using a separate buffer to store coverage information for pixels in
the color buffers. It also provided a mechanism to disable writing
to the coverage buffer when coverage sample filtering was not needed
or undesirable. However, it did not provide a way to disable
reading data from the coverage buffer at resolve time. In some
cases performance can be improved by eliminating these memory reads.
To that end, this extension exposes a surface attribute that allows
applications to specify when no coverage sample resolve is desired.
IP Status
NVIDIA Proprietary
New Types
None
New Procedures and Functions
None
New Tokens
Accepted by the <attribute> parameter of eglSurfaceAttrib and
eglQuerySurface:
EGL_COVERAGE_SAMPLE_RESOLVE_NV 0x3131
Accepted by the <value> parameter of eglSurfaceAttrib and returned
in the <value> parameter of eglQuerySurface when <attribute> is
EGL_COVERAGE_SAMPLE_RESOLVE_NV:
EGL_COVERAGE_SAMPLE_RESOLVE_DEFAULT_NV 0x3132
EGL_COVERAGE_SAMPLE_RESOLVE_NONE_NV 0x3133
Additions to Chapter 3 of the EGL 1.4 Specification (EGL Functions and
Errors)
Additions to section 3.5.6 (Surface Attributes)
Replace the last sentence of paragraph 2 (p. 35):
"Attributes that can be specified are
EGL_COVERAGE_SAMPLE_RESOLVE_NV, EGL_MIPMAP_LEVEL,
EGL_MULTISAMPLE_RESOLVE, and EGL_SWAP_BEHAVIOR."
Add the following paragraphs between paragraphs 2 and 3 (p. 35):
"If <attribute> is EGL_COVERAGE_SAMPLE_RESOLVE_NV, then <value>
specifies the filter to use when resolving the coverage sample
buffer. A <value> of EGL_COVERAGE_SAMPLE_RESOLVE_DEFAULT_NV chooses
the default implementation-defined filtering method, while
EGL_MULTISAMPLE_RESOLVE_NONE_NV disables filtering based on coverage
data.
"The initial value of EGL_COVERAGE_SAMPLE_RESOLVE_NV is
EGL_COVERAGE_SAMPLE_RESOLVE_DEFAULT_NV."
Add the following paragraph after paragraph 13 (p. 36):
"Querying EGL_COVERAGE_SAMPLE_RESOLVE_NV returns the filtering
method used when performing coverage buffer resolution. The filter
may be either EGL_COVERAGE_SAMPLE_RESOLVE_DEFAULT_NV or
EGL_COVERAGE_SAMPLE_RESOLVE_NONE_NV, as described above for
eglSurfaceAttrib."
Interactions with EGL_NV_coverage_sample:
This extension relies on language in EGL_NV_coverage_sample to
describe the coverage sample buffer.
If EGL_NV_coverage_sample is not present, this extension has no
effect on rendering.
Issues
1. Should it be an error to set EGL_COVERAGE_SAMPLE_RESOLVE_NV on
surfaces that don't have a coverage buffer?
RESOLVED: No. EGL_COVERAGE_SAMPLE_RESOLVE_DEFAULT_NV will behave
the same as EGL_COVERAGE_SAMPLE_RESOLVE_NONE_NV in this case.
Revision History
#1 (James Jones, 2011-04-13)
- Initial revision.
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