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Name
ANGLE_stencil_texturing
Name Strings
GL_ANGLE_stencil_texturing
Contributors
Contributors to ARB_stencil_texturing
Members of the WebGL working group
Status
Draft
Version
Last Modified Date: March 1, 2023
Revision: 1
Number
OpenGL ES Extension XX
Dependencies
This extension is written against the OpenGL ES 3.0 Specification.
OpenGL ES 3.0 and OpenGL ES Shading Language 3.00 are required.
Overview
This extension allows texturing of the stencil component of a packed depth
stencil texture. Stencil values are returned as unsigned integers. It is
not possible to sample both depth and stencil values from the same
texture, and this extension allows the app to select which is sampled for
the bound texture.
This extension provides similar functionality to that of OpenGL ES 3.1.
New Procedures and Functions
None
New Tokens
Accepted by the <pname> parameter of TexParameter* and GetTexParameter*:
DEPTH_STENCIL_TEXTURE_MODE_ANGLE 0x90EA
STENCIL_INDEX_ANGLE 0x1901
Additions to the OpenGL ES 3.0 Specification
Changes to Section 3.9.2.1 (Texture Access), page 167
Add a new new bullet point on page 168:
"* The sampler used in a texture lookup function is one of the shadow
sampler types, the texture object's internal format is DEPTH_STENCIL,
and the DEPTH_STENCIL_TEXTURE_MODE_ANGLE is not DEPTH_COMPONENT."
Then change the following paragraph that reads:
"The stencil texture internal component is ignored if the base internal
format is DEPTH_STENCIL."
To the following:
"The stencil index texture internal component is ignored if the base
internal format is DEPTH_STENCIL and the value of
DEPTH_STENCIL_TEXTURE_MODE_ANGLE is not STENCIL_INDEX_ANGLE.
Texture lookups involving texture objects with an internal format
of DEPTH_STENCIL can read the stencil value as described in section
3.8 by setting the DEPTH_STENCIL_TEXTURE_MODE_ANGLE to STENCIL_INDEX_ANGLE.
The stencil value is read as an integer and assigned to R_t. An unsigned
integer sampler should be used to lookup the stencil component, otherwise
the results are undefined."
Changes to Section 3.8.7 (Texture Parameters), page 150
In Table 3.20 (Texture parameters and their values) add the following
entry:
"
Name Type Legal Values
------------- ---- ------------------------------------
DEPTH_STENCIL_TEXTURE_MODE_ANGLE enum DEPTH_COMPONENT, STENCIL_INDEX_ANGLE
"
Changes to Section 3.8.12 (Combined Depth/Stencil Textures), page 160
Modify the paragraph to read:
"If the texture image has a base internal format of DEPTH_STENCIL, then
the stencil index texture component is ignored by default. The texture
value <T> does not include a stencil index component, but includes
only the depth component.
In order to access the stencil index texture component, the
DEPTH_STENCIL_TEXTURE_MODE_ANGLE texture parameter should be set to
STENCIL_INDEX_ANGLE. When this mode is set the depth component is ignored
and the texture value includes only the stencil index component.
The stencil index value is treated as an unsigned integer texture and
returns an unsigned integer value when sampled. When sampling the stencil
index only NEAREST filtering is supported.
The DEPTH_STENCIL_TEXTURE_MODE_ANGLE is ignored for non depth/stencil
textures."
Changes to Section 3.8.13 (Texture Completeness), page 161
Add a new bullet point for the conditions that cause the texture
to not be complete:
"* The internal format of the texture is DEPTH_STENCIL, the value of
DEPTH_STENCIL_TEXTURE_MODE_ANGLE for the texture is STENCIL_INDEX_ANGLE,
and either the magnification filter is not NEAREST or the minification
filter is neither NEAREST nor NEAREST_MIPMAP_NEAREST."
Changes to Section 3.8.15 (Texture Comparison Modes), page 163
Modify the following paragraph:
"Let Dt be the depth texture value and St be the stencil index component
of a depth/stencil texture. If there is no stencil component the value of
St is undefined. Let Dref be the reference value..."
Insert a new paragraph after the paragraphs that ends:
"Then the effective texture value is computed as follows:
If the base internal format is DEPTH_STENCIL and the value of
DEPTH_STENCIL_TEXTURE_MODE_ANGLE is STENCIL_INDEX_ANGLE, then
r = St
Otherwise, if the value of TEXTURE_COMPARE_MODE is NONE, then
r = Dt
Otherwise, if the value of TEXTURE_COMPARE_MODE is
COMPARE_REF_TO_TEXTURE, then r depends on the texture comparison
function as shown in table 3.23.
The resulting r is assigned ..."
New State
(Table 6.9, Textures) add the following entry:
Get Value Type Get Command Initial Value Description Section
-------------------------------- ---- ----------------- --------------- -------------------------- -------
DEPTH_STENCIL_TEXTURE_MODE_ANGLE Z2 GetTexParameteriv DEPTH_COMPONENT Depth stencil texture mode 3.8.7
Revision History
3/1/2023 First revision
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