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author | marha <marha@users.sourceforge.net> | 2012-06-08 14:29:46 +0200 |
---|---|---|
committer | marha <marha@users.sourceforge.net> | 2012-06-08 14:50:37 +0200 |
commit | 72ec0e3bb2d7fc6b77b2a75873792f781679da6a (patch) | |
tree | 0a736ab9a8c26276929ab077dc661e3625b54884 /mesalib/docs/MESA_texture_signed_rgba.spec | |
parent | 5e865910f0ce672295bd60460631339be5e311a0 (diff) | |
parent | 990bc3f015a4f8fce2eb918375defcd44980a845 (diff) | |
download | vcxsrv-72ec0e3bb2d7fc6b77b2a75873792f781679da6a.tar.gz vcxsrv-72ec0e3bb2d7fc6b77b2a75873792f781679da6a.tar.bz2 vcxsrv-72ec0e3bb2d7fc6b77b2a75873792f781679da6a.zip |
Merge remote-tracking branch 'origin/released'
Conflicts:
fontconfig/.gitignore
libX11/src/ConvSel.c
libX11/src/CrGlCur.c
libX11/src/CrWindow.c
libX11/src/GetDflt.c
libX11/src/Window.c
libX11/src/xlibi18n/XimProto.h
libX11/src/xlibi18n/lcDynamic.c
libxcb/src/.gitignore
libxcb/src/xcb_ext.c
libxcb/src/xcb_xid.c
mesalib/src/glsl/.gitignore
mesalib/src/glsl/glcpp/.gitignore
mesalib/src/mapi/glapi/gen/glX_API.xml
mesalib/src/mapi/glapi/glapi_getproc.c
mesalib/src/mesa/main/.gitignore
mesalib/src/mesa/main/syncobj.c
mesalib/src/mesa/program/.gitignore
xkbcomp/listing.c
xkbcomp/xkbpath.c
xorg-server/.gitignore
xorg-server/Xext/xvmain.c
xorg-server/dix/dispatch.c
xorg-server/hw/xwin/glx/winpriv.h
xorg-server/hw/xwin/winprefsyacc.y
xorg-server/hw/xwin/winscrinit.c
xorg-server/xkeyboard-config/rules/bin/ml1_s.sh
xorg-server/xkeyboard-config/rules/bin/ml1v1_s.sh
xorg-server/xkeyboard-config/rules/bin/ml1v_s.sh
xorg-server/xkeyboard-config/rules/bin/ml_s.sh
xorg-server/xkeyboard-config/rules/bin/mlv_s.sh
xorg-server/xkeyboard-config/rules/compat/.gitignore
Diffstat (limited to 'mesalib/docs/MESA_texture_signed_rgba.spec')
-rw-r--r-- | mesalib/docs/MESA_texture_signed_rgba.spec | 428 |
1 files changed, 214 insertions, 214 deletions
diff --git a/mesalib/docs/MESA_texture_signed_rgba.spec b/mesalib/docs/MESA_texture_signed_rgba.spec index bcc4d4203..e3a6b59af 100644 --- a/mesalib/docs/MESA_texture_signed_rgba.spec +++ b/mesalib/docs/MESA_texture_signed_rgba.spec @@ -1,214 +1,214 @@ -Name
-
- MESA_texture_signed_rgba
-
-Name Strings
-
- GL_MESA_texture_signed_rgba
-
-Contact
-
-
-
-Notice
-
-
-
-IP Status
-
- No known IP issues
-
-Status
-
-
-
-Version
-
- 0.3, 2009-03-24
-
-Number
-
- Not assigned ?
-
-Dependencies
-
- Written based on the wording of the OpenGL 2.0 specification.
-
- This extension trivially interacts with ARB_texture_float.
- This extension shares some language with ARB_texture_compression_rgtc
- but does not depend on it.
-
-Overview
-
- OpenGL prior to 3.1 does not support any signed texture formats.
- ARB_texture_compression_rgtc introduces some compressed red and
- red_green signed formats but no uncompressed ones, which might
- still be useful. NV_texture_shader adds signed texture formats,
- but also a lot of functionality which has been superseded by fragment
- shaders.
- It is usually possible to get the same functionality
- using a unsigned format by doing scale and bias in a shader, but this
- is undesirable since modern hardware has direct support for this.
- This extension adds a signed 4-channel texture format by backporting
- the relevant features from OpenGL 3.1, as a means to support this in
- OpenGL implementations only supporting older versions.
-
-Issues
-
- 1) What should this extension be called?
-
- RESOLVED: MESA_texture_signed_rgba seems reasonable.
- The rgba part is there because only 4 channel format is supported.
-
-
- 2) Should the full set of signed formats (alpha, luminance, rgb, etc.)
- be supported?
-
- RESOLVED: NO. To keep this extension simple, only add the most
- universal format, rgba. alpha/luminance can't be trivially supported
- since OpenGL 3.1 does not support them any longer, and there is some
- implied dependency on ARB_texture_rg for red/red_green formats so
- avoid all this. Likewise, only 8 bits per channel is supported.
-
-
- 3) Should this extension use new enums for the texture formats?
-
- RESOLVED: NO. Same enums as those used in OpenGL 3.1.
-
-
- 4) How are signed integer values mapped to floating-point values?
-
- RESOLVED: Same as described in issue 5) of
- ARB_texture_compression_rgtc (quote):
- A signed 8-bit two's complement value X is computed to
- a floating-point value Xf with the formula:
-
- { X / 127.0, X > -128
- Xf = {
- { -1.0, X == -128
-
- This conversion means -1, 0, and +1 are all exactly representable,
- however -128 and -127 both map to -1.0. Mapping -128 to -1.0
- avoids the numerical awkwardness of have a representable value
- slightly more negative than -1.0.
-
- This conversion is intentionally NOT the "byte" conversion listed
- in Table 2.9 for component conversions. That conversion says:
-
- Xf = (2*X + 1) / 255.0
-
- The Table 2.9 conversion is incapable of exactly representing
- zero.
-
- (Difference to ARB_texture_compression_rgtc):
- This is the same mapping as OpenGL 3.1 uses.
- This is also different to what NV_texture_shader used.
- The above mapping should be considered the reference, but there
- is some leeway so other mappings are allowed for implementations which
- cannot do this. Particularly the mapping given in NV_texture_shader or
- the standard OpenGL byte/float mapping is considered acceptable too, as
- might be a mapping which represents -1.0 by -128, 0.0 by 0 and 1.0 by
- 127 (that is, uses different scale factors for negative and positive
- numbers).
- Also, it is ok to store incoming GL_BYTE user data as-is, without
- converting to GL_FLOAT (using the standard OpenGL float/byte mapping)
- and converting back (using the mapping described here).
- Other than those subtle issues there are no other non-standard
- conversions used, so when using for instance CopyTexImage2D with
- a framebuffer clamped to [0,1] all converted numbers will be in the range
- [0, 127] (and not scaled and biased).
-
-
- 5) How will signed components resulting from RGBA8_SNORM texture
- fetches interact with fragment coloring?
-
- RESOLVED: Same as described in issue 6) of
- ARB_texture_compression_rgtc (quote):
- The specification language for this extension is silent
- about clamping behavior leaving this to the core specification
- and other extensions. The clamping or lack of clamping is left
- to the core specification and other extensions.
-
- For assembly program extensions supporting texture fetches
- (ARB_fragment_program, NV_fragment_program, NV_vertex_program3,
- etc.) or the OpenGL Shading Language, these signed formats will
- appear as expected with unclamped signed components as a result
- of a texture fetch instruction.
-
- If ARB_color_buffer_float is supported, its clamping controls
- will apply.
-
- NV_texture_shader extension, if supported, adds support for
- fixed-point textures with signed components and relaxed the
- fixed-function texture environment clamping appropriately. If the
- NV_texture_shader extension is supported, its specified behavior
- for the texture environment applies where intermediate values
- are clamped to [-1,1] unless stated otherwise as in the case
- of explicitly clamped to [0,1] for GL_COMBINE. or clamping the
- linear interpolation weight to [0,1] for GL_DECAL and GL_BLEND.
-
- Otherwise, the conventional core texture environment clamps
- incoming, intermediate, and output color components to [0,1].
-
- This implies that the conventional texture environment
- functionality of unextended OpenGL 1.5 or OpenGL 2.0 without
- using GLSL (and with none of the extensions referred to above)
- is unable to make proper use of the signed texture formats added
- by this extension because the conventional texture environment
- requires texture source colors to be clamped to [0,1]. Texture
- filtering of these signed formats would be still signed, but
- negative values generated post-filtering would be clamped to
- zero by the core texture environment functionality. The
- expectation is clearly that this extension would be co-implemented
- with one of the previously referred to extensions or used with
- GLSL for the new signed formats to be useful.
-
-
- 6) Should the RGBA_SNORM tokens also be accepted by CopyTexImage
- functions?
-
- RESOLVED: YES.
-
-
- 7) What to do with GetTexParameter if ARB_texture_float is supported,
- in particular what datatype should this return for TEXTURE_RED_TYPE_ARB,
- TEXTURE_GREEN_TYPE_ARB, TEXTURE_BLUE_TYPE_ARB, TEXTURE_ALPHA_TYPE_ARB?
-
- RESOLVED: ARB_texture_float states type is either NONE,
- UNSIGNED_NORMALIZED_ARB, or FLOAT. This extension adds a new enum,
- SIGNED_NORMALIZED, which will be returned accordingly. This is the
- same behaviour as in OpenGL 3.1.
-
-
-New Tokens
-
-
- Accepted by the <internalformat> parameter of
- TexImage1D, TexImage2D, TexImage3D, CopyTexImage1D, and CopyTexImage2D:
-
- RGBA_SNORM 0x8F93
- RGBA8_SNORM 0x8F97
-
- Returned by the <params> parameter of GetTexLevelParameter:
-
- SIGNED_NORMALIZED 0x8F9C
-
-
-Additions to Chapter 3 of the OpenGL 2.0 Specification (Rasterization):
-
- -- Section 3.8.1, Texture Image Specification
-
- Add to Table 3.16 (page 154): Sized internal formats
-
- Sized Base R G B A L I D
- Internal Format Internal Format bits bits bits bits bits bits bits
- --------------- --------------- ---- ---- ---- ---- ---- ---- ----
- RGBA8_SNORM RGBA 8 8 8 8 0 0 0
-
-
-Dependencies on ARB_texture_float extension:
-
- If ARB_texture_float is supported, GetTexParameter queries with <value>
- of TEXTURE_RED_TYPE_ARB, TEXTURE_GREEN_TYPE_ARB, TEXTURE_BLUE_TYPE_ARB or
- TEXTURE_ALPHA_TYPE_ARB return SIGNED_NORMALIZED if
- the base internal format is RGBA_SNORM.
+Name + + MESA_texture_signed_rgba + +Name Strings + + GL_MESA_texture_signed_rgba + +Contact + + + +Notice + + + +IP Status + + No known IP issues + +Status + + + +Version + + 0.3, 2009-03-24 + +Number + + Not assigned ? + +Dependencies + + Written based on the wording of the OpenGL 2.0 specification. + + This extension trivially interacts with ARB_texture_float. + This extension shares some language with ARB_texture_compression_rgtc + but does not depend on it. + +Overview + + OpenGL prior to 3.1 does not support any signed texture formats. + ARB_texture_compression_rgtc introduces some compressed red and + red_green signed formats but no uncompressed ones, which might + still be useful. NV_texture_shader adds signed texture formats, + but also a lot of functionality which has been superseded by fragment + shaders. + It is usually possible to get the same functionality + using a unsigned format by doing scale and bias in a shader, but this + is undesirable since modern hardware has direct support for this. + This extension adds a signed 4-channel texture format by backporting + the relevant features from OpenGL 3.1, as a means to support this in + OpenGL implementations only supporting older versions. + +Issues + + 1) What should this extension be called? + + RESOLVED: MESA_texture_signed_rgba seems reasonable. + The rgba part is there because only 4 channel format is supported. + + + 2) Should the full set of signed formats (alpha, luminance, rgb, etc.) + be supported? + + RESOLVED: NO. To keep this extension simple, only add the most + universal format, rgba. alpha/luminance can't be trivially supported + since OpenGL 3.1 does not support them any longer, and there is some + implied dependency on ARB_texture_rg for red/red_green formats so + avoid all this. Likewise, only 8 bits per channel is supported. + + + 3) Should this extension use new enums for the texture formats? + + RESOLVED: NO. Same enums as those used in OpenGL 3.1. + + + 4) How are signed integer values mapped to floating-point values? + + RESOLVED: Same as described in issue 5) of + ARB_texture_compression_rgtc (quote): + A signed 8-bit two's complement value X is computed to + a floating-point value Xf with the formula: + + { X / 127.0, X > -128 + Xf = { + { -1.0, X == -128 + + This conversion means -1, 0, and +1 are all exactly representable, + however -128 and -127 both map to -1.0. Mapping -128 to -1.0 + avoids the numerical awkwardness of have a representable value + slightly more negative than -1.0. + + This conversion is intentionally NOT the "byte" conversion listed + in Table 2.9 for component conversions. That conversion says: + + Xf = (2*X + 1) / 255.0 + + The Table 2.9 conversion is incapable of exactly representing + zero. + + (Difference to ARB_texture_compression_rgtc): + This is the same mapping as OpenGL 3.1 uses. + This is also different to what NV_texture_shader used. + The above mapping should be considered the reference, but there + is some leeway so other mappings are allowed for implementations which + cannot do this. Particularly the mapping given in NV_texture_shader or + the standard OpenGL byte/float mapping is considered acceptable too, as + might be a mapping which represents -1.0 by -128, 0.0 by 0 and 1.0 by + 127 (that is, uses different scale factors for negative and positive + numbers). + Also, it is ok to store incoming GL_BYTE user data as-is, without + converting to GL_FLOAT (using the standard OpenGL float/byte mapping) + and converting back (using the mapping described here). + Other than those subtle issues there are no other non-standard + conversions used, so when using for instance CopyTexImage2D with + a framebuffer clamped to [0,1] all converted numbers will be in the range + [0, 127] (and not scaled and biased). + + + 5) How will signed components resulting from RGBA8_SNORM texture + fetches interact with fragment coloring? + + RESOLVED: Same as described in issue 6) of + ARB_texture_compression_rgtc (quote): + The specification language for this extension is silent + about clamping behavior leaving this to the core specification + and other extensions. The clamping or lack of clamping is left + to the core specification and other extensions. + + For assembly program extensions supporting texture fetches + (ARB_fragment_program, NV_fragment_program, NV_vertex_program3, + etc.) or the OpenGL Shading Language, these signed formats will + appear as expected with unclamped signed components as a result + of a texture fetch instruction. + + If ARB_color_buffer_float is supported, its clamping controls + will apply. + + NV_texture_shader extension, if supported, adds support for + fixed-point textures with signed components and relaxed the + fixed-function texture environment clamping appropriately. If the + NV_texture_shader extension is supported, its specified behavior + for the texture environment applies where intermediate values + are clamped to [-1,1] unless stated otherwise as in the case + of explicitly clamped to [0,1] for GL_COMBINE. or clamping the + linear interpolation weight to [0,1] for GL_DECAL and GL_BLEND. + + Otherwise, the conventional core texture environment clamps + incoming, intermediate, and output color components to [0,1]. + + This implies that the conventional texture environment + functionality of unextended OpenGL 1.5 or OpenGL 2.0 without + using GLSL (and with none of the extensions referred to above) + is unable to make proper use of the signed texture formats added + by this extension because the conventional texture environment + requires texture source colors to be clamped to [0,1]. Texture + filtering of these signed formats would be still signed, but + negative values generated post-filtering would be clamped to + zero by the core texture environment functionality. The + expectation is clearly that this extension would be co-implemented + with one of the previously referred to extensions or used with + GLSL for the new signed formats to be useful. + + + 6) Should the RGBA_SNORM tokens also be accepted by CopyTexImage + functions? + + RESOLVED: YES. + + + 7) What to do with GetTexParameter if ARB_texture_float is supported, + in particular what datatype should this return for TEXTURE_RED_TYPE_ARB, + TEXTURE_GREEN_TYPE_ARB, TEXTURE_BLUE_TYPE_ARB, TEXTURE_ALPHA_TYPE_ARB? + + RESOLVED: ARB_texture_float states type is either NONE, + UNSIGNED_NORMALIZED_ARB, or FLOAT. This extension adds a new enum, + SIGNED_NORMALIZED, which will be returned accordingly. This is the + same behaviour as in OpenGL 3.1. + + +New Tokens + + + Accepted by the <internalformat> parameter of + TexImage1D, TexImage2D, TexImage3D, CopyTexImage1D, and CopyTexImage2D: + + RGBA_SNORM 0x8F93 + RGBA8_SNORM 0x8F97 + + Returned by the <params> parameter of GetTexLevelParameter: + + SIGNED_NORMALIZED 0x8F9C + + +Additions to Chapter 3 of the OpenGL 2.0 Specification (Rasterization): + + -- Section 3.8.1, Texture Image Specification + + Add to Table 3.16 (page 154): Sized internal formats + + Sized Base R G B A L I D + Internal Format Internal Format bits bits bits bits bits bits bits + --------------- --------------- ---- ---- ---- ---- ---- ---- ---- + RGBA8_SNORM RGBA 8 8 8 8 0 0 0 + + +Dependencies on ARB_texture_float extension: + + If ARB_texture_float is supported, GetTexParameter queries with <value> + of TEXTURE_RED_TYPE_ARB, TEXTURE_GREEN_TYPE_ARB, TEXTURE_BLUE_TYPE_ARB or + TEXTURE_ALPHA_TYPE_ARB return SIGNED_NORMALIZED if + the base internal format is RGBA_SNORM. |