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| author | Wollnashorn <Wollnashorn@users.noreply.github.com> | 2023-04-05 01:29:46 +0200 |
|---|---|---|
| committer | Wollnashorn <Wollnashorn@users.noreply.github.com> | 2023-04-08 16:12:30 +0200 |
| commit | 780240e6979b198e7bd10feaad5399b8b4b63762 (patch) | |
| tree | c145f48c66cf003e618cefc63496e3f5b7637f56 /src/shader_recompiler/backend/glsl/emit_glsl_image.cpp | |
| parent | bbdfe1fab1f1706b7e6a62d93951bb451bbeec43 (diff) | |
shader_recompiler: Add subpixel offset for correct rounding at `ImageGather`
On AMD a subpixel offset of 1/512 of the texel size is applied to the texture coordinates at a ImageGather call to ensure the rounding at the texel centers is done the same way as in Maxwell or other Nvidia architectures.
See https://www.reedbeta.com/blog/texture-gathers-and-coordinate-precision/ for more details why this might be necessary.
This should fix shadow artifacts at object edges in Zelda: Breath of the Wild (#9957, #6956).
Diffstat (limited to 'src/shader_recompiler/backend/glsl/emit_glsl_image.cpp')
| -rw-r--r-- | src/shader_recompiler/backend/glsl/emit_glsl_image.cpp | 29 |
1 files changed, 29 insertions, 0 deletions
diff --git a/src/shader_recompiler/backend/glsl/emit_glsl_image.cpp b/src/shader_recompiler/backend/glsl/emit_glsl_image.cpp index f335c8af04..418505475e 100644 --- a/src/shader_recompiler/backend/glsl/emit_glsl_image.cpp +++ b/src/shader_recompiler/backend/glsl/emit_glsl_image.cpp @@ -143,6 +143,21 @@ IR::Inst* PrepareSparse(IR::Inst& inst) { } return sparse_inst; } + +std::string ImageGatherSubpixelOffset(const IR::TextureInstInfo& info, std::string_view texture, + std::string_view coords) { + switch (info.type) { + case TextureType::Color2D: + case TextureType::Color2DRect: + return fmt::format("{}+vec2(0.001953125)/vec2(textureSize({}, 0))", coords, texture); + case TextureType::ColorArray2D: + case TextureType::ColorCube: + return fmt::format("vec3({0}.xy+vec2(0.001953125)/vec2(textureSize({1}, 0)),{0}.z)", coords, + texture); + default: + return std::string{coords}; + } +} } // Anonymous namespace void EmitImageSampleImplicitLod(EmitContext& ctx, IR::Inst& inst, const IR::Value& index, @@ -340,6 +355,13 @@ void EmitImageGather(EmitContext& ctx, IR::Inst& inst, const IR::Value& index, LOG_WARNING(Shader_GLSL, "Device does not support sparse texture queries. STUBBING"); ctx.AddU1("{}=true;", *sparse_inst); } + std::string coords_with_subpixel_offset; + if (ctx.profile.need_gather_subpixel_offset) { + // Apply a subpixel offset of 1/512 the texel size of the texture to ensure same rounding on + // AMD hardware as on Maxwell or other Nvidia architectures. + coords_with_subpixel_offset = ImageGatherSubpixelOffset(info, texture, coords); + coords = coords_with_subpixel_offset; + } if (!sparse_inst || !supports_sparse) { if (offset.IsEmpty()) { ctx.Add("{}=textureGather({},{},int({}));", texel, texture, coords, @@ -387,6 +409,13 @@ void EmitImageGatherDref(EmitContext& ctx, IR::Inst& inst, const IR::Value& inde LOG_WARNING(Shader_GLSL, "Device does not support sparse texture queries. STUBBING"); ctx.AddU1("{}=true;", *sparse_inst); } + std::string coords_with_subpixel_offset; + if (ctx.profile.need_gather_subpixel_offset) { + // Apply a subpixel offset of 1/512 the texel size of the texture to ensure same rounding on + // AMD hardware as on Maxwell or other Nvidia architectures. + coords_with_subpixel_offset = ImageGatherSubpixelOffset(info, texture, coords); + coords = coords_with_subpixel_offset; + } if (!sparse_inst || !supports_sparse) { if (offset.IsEmpty()) { ctx.Add("{}=textureGather({},{},{});", texel, texture, coords, dref); |