EXT_texture_mirror_clamp_to_edge
Name
EXT_texture_mirror_clamp_to_edge
Name Strings
GL_EXT_texture_mirror_clamp_to_edge
Contact
Christophe Riccio, Unity Technologies (christophe.riccio 'at' unity3d.com)
Contributors
Contributors to ARB_texture_mirror_clamp_to_edge
Ian Romanick
Daniel Koch
Notice
Copyright (c) 2017 The Khronos Group Inc. Copyright terms at
http://www.khronos.org/registry/speccopyright.html
Status
Completed on September 7, 2017.
Version
Last Modified Date: September 7, 2017
Revision 2
Number
ES Extension #291
Dependencies
OpenGL ES 2.0 is required.
This extension interacts with OpenGL ES 3.0.
This extension interacts with OpenGL ES 3.2.
This extension interacts with OES_texture_3D.
This extension is written against the OpenGL ES 3.2 Specification.
Overview
EXT_texture_mirror_clamp_to_edge extends the set of texture wrap modes to
include an additional mode (GL_MIRROR_CLAMP_TO_EDGE_EXT) that effectively uses
a texture map twice as large as the original image in which the additional
half of the new image is a mirror image of the original image.
This new mode relaxes the need to generate images whose opposite edges
match by using the original image to generate a matching "mirror image".
This mode allows the texture to be mirrored only once in the negative
s, t, and r directions.
New Procedure and Functions
None
New Tokens
Accepted by the <param> parameter of TexParameter{if}, SamplerParameter{if}
and SamplerParameter{if}v, and by the <params> parameter of
TexParameter{if}v, TexParameterI{i ui}v and SamplerParameterI{i ui}v when
their <pname> parameter is TEXTURE_WRAP_S, TEXTURE_WRAP_T, or
TEXTURE_WRAP_R:
MIRROR_CLAMP_TO_EDGE_EXT 0x8743 (same value as OpenGL core MIRROR_CLAMP_TO_EDGE)
Additions to Chapter 8 if the OpenGL ES 3.2 Specification (Textures and Samplers)
In section 8.10 (Texture Parameters) modify the table entries for Table 8.16 (Texture parameters and their values) for TEXTURE_WRAP_S, TEXTURE_WRAP_T, and TEXTURE_WRAP_R and add the following to the "Legal Values" column:
Name Type Legal Values
--------------- ---- ------------
TEXTURE_WRAP_S enum (.. as before)
MIRROR_CLAMP_TO_EDGE
TEXTURE_WRAP_T enum (.. as before)
MIRROR_CLAMP_TO_EDGE
TEXTURE_WRAP_R enum (.. as before)
MIRROR_CLAMP_TO_EDGE
In section 8.14.2 (Coordinate Wrapping and Texel Selection) add the following row to Table 8.19 (Texel location wrap mode application):
Wrap mode Result of wrap(coord)
--------- ---------------------
(previous entries..)
MIRROR_CLAMP_TO_EDGE min(1-1/(2*size), max(1/(2*size), abs(coord)))
Additions to the GLX Specification
None
GLX Protocol
None
Dependencies on OES_texture_3D or equivalent
If OES_texture_3D or equivalent functionality is not implemented,
then the references to clamping of 3D textures in this file are
invalid, and references to TEXTURE_WRAP_R should be ignored.
Dependencies on OpenGL ES 3.0 or equivalent
If OpenGL ES 3.0 or equivalent is not supported, then ignore all
references to sampler objects and SamplerParameter* functions.
Dependencies on OpenGL ES 3.2 or equivalent
If OpenGL ES 3.2 or equivalent is not supported, then ignore all
references to the TexParameterI* and SamplerParameterI* functions.
New State
Only the type information changes for these parameters:
Update Table 21.10 (Textures - state per texture object)
Get Value Get Command Type Initial Value (...)
--------- ----------- ---- -------------
TEXTURE_WRAP_S GetTexParameter n x Z5 see sec 8.19 (...)
TEXTURE_WRAP_T GetTexParameter n x Z5 see sec 8.19 (...)
TEXTURE_WRAP_R GetTexParameter n x Z5 see sec 8.19 (...)
Update Table 21.12 (Textures - state per sampler object)
Get Value Get Command Type Initial Value (...)
--------- ----------- ---- -------------
TEXTURE_WRAP_S GetSamplerParameteriv n x Z5 see sec 8.19 (...)
TEXTURE_WRAP_T GetSamplerParameteriv n x Z5 see sec 8.19 (...)
TEXTURE_WRAP_R GetSamplerParameteriv n x Z5 see sec 8.19 (...)
New Implementation Dependent State
None
Issues
None
Revision History
Revision 2 - September 7, 2017 (criccio)
- Require OpenGL ES 2.0 instead of OpenGL ES 3.0
Revision 1 - September 5, 2017 (criccio)
- Initial EXT version based on ARB_texture_mirror_clamp_to_edge