For the SAMPLE_POS and SAMPLE_INFO opcodes, clarify resource vs. render target queries, range of postion values, swizzling, etc. We basically follow the DX10.1 conventions.
For the TXQS opcode and TGSI_SEMANTIC_SAMPLEID, clarify return value and type. For the TGSI_SEMANTIC_SAMPLEPOS system value, clarify the range of positions returned. --- src/gallium/docs/source/tgsi.rst | 53 +++++++++++++++++++++++++++++++--------- 1 file changed, 42 insertions(+), 11 deletions(-) diff --git a/src/gallium/docs/source/tgsi.rst b/src/gallium/docs/source/tgsi.rst index 7fb963f..310b49d 100644 --- a/src/gallium/docs/source/tgsi.rst +++ b/src/gallium/docs/source/tgsi.rst @@ -982,7 +982,9 @@ XXX doesn't look like most of the opcodes really belong here. .. opcode:: TXQS - Texture Samples Query This retrieves the number of samples in the texture, and stores it - into the x component. The other components are undefined. + into the x component as an unsigned integer. The other components are + undefined. If the texture is not multisampled, this function returns + (1, 0, 0, 0). .. math:: @@ -2538,14 +2540,40 @@ after lookup. .. opcode:: SAMPLE_POS - Query the position of a given sample. dst receives float4 (x, y, 0, 0) - indicated where the sample is located. If the resource is not a multi-sample - resource and not a render target, the result is 0. + Query the position of a sample in the given resource or render target + when per-sample fragment shading is in effect. + + Syntax: ``SAMPLE_POS dst, source, sample_index`` + + dst receives float4 (x, y, 0, 0) indicated where the sample is located. + Sample locations are in the range [0, 1] where 0.5 is the center of the + fragment. + + source is either a sampler view (to indicate a shader resource) or temp + register (to indicate the render target). The source register may have + an optional swizzle to apply to the returned result + + sample_index is an integer scalar indicating which sample position is to + be queried. + + If per-sample shading is not in effect or the source resource or render + target is not multisampled, the result is (0, 0, 0, 0). .. opcode:: SAMPLE_INFO - dst receives number of samples in x. If the resource is not a multi-sample - resource and not a render target, the result is 0. + Query the number of samples in a multisampled resource or render target. + + Syntax: ``SAMPLE_INFO dst, source`` + + dst receives int4 (n, 0, 0, 0) where n is the number of samples in a + resource or the render target. + + source is either a sampler view (to indicate a shader resource) or temp + register (to indicate the render target). The source register may have + an optional swizzle to apply to the returned result + + If per-sample shading is not in effect or the source resource or render + target is not multisampled, the result is (1, 0, 0, 0). .. _resourceopcodes: @@ -3284,15 +3312,18 @@ TGSI_SEMANTIC_SAMPLEID """""""""""""""""""""" For fragment shaders, this semantic label indicates that a system value -contains the current sample id (i.e. gl_SampleID). -This is an integer value, and only the X component is used. +contains the current sample id (i.e. gl_SampleID) as an unsigned int. +Only the X component is used. If per-sample shading is not enabled, +the result is (0, 0, 0, 0). TGSI_SEMANTIC_SAMPLEPOS """"""""""""""""""""""" -For fragment shaders, this semantic label indicates that a system value -contains the current sample's position (i.e. gl_SamplePosition). Only the X -and Y values are used. +For fragment shaders, this semantic label indicates that a system +value contains the current sample's position as float4(x, y, 0, 0) in +the render target (i.e. gl_SamplePosition) when per-fragment shading +is in effect. Position values are in the range [0, 1] where 0.5 is +the center of the fragment. TGSI_SEMANTIC_SAMPLEMASK """""""""""""""""""""""" -- 1.9.1 _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev
