feat(shader): implement texture component type handling in SPIR-V backend

- Add ComponentScalarType helper function
- Update ImageType to use component-specific sampled types
- Add TextureColorResultType and TextureSampleResultToFloat helpers
- Update all texture sampling functions to handle component types correctly
- Add proper type conversions for integer and stencil textures
- Add Flat decorations for integer inputs in fragment shaders
- Add NonWritable decoration for read-only storage buffers

This ensures textures are sampled with the correct component types,
improving accuracy for integer and depth/stencil textures.

Co-Authored-By: ForrestMarkX <forrestmarkx@outlook.com>
Signed-off-by: Zephyron <zephyron@citron-emu.org>

src/shader_recompiler/backend/spirv/emit_spirv_image.cpp

@@ -1,4 +1,5 @@
 // SPDX-FileCopyrightText: Copyright 2021 yuzu Emulator Project
+// SPDX-FileCopyrightText: Copyright 2025 citron Emulator Project
 // SPDX-License-Identifier: GPL-2.0-or-later
 
 #include <boost/container/static_vector.hpp>
@@ -195,6 +196,41 @@ Id Texture(EmitContext& ctx, IR::TextureInstInfo info, [[maybe_unused]] const IR
     }
 }
 
+Id TextureColorResultType(EmitContext& ctx, const TextureDefinition& def) {
+    switch (def.component_type) {
+    case SamplerComponentType::Float:
+    case SamplerComponentType::Depth:
+        return ctx.F32[4];
+    case SamplerComponentType::Sint:
+        return ctx.S32[4];
+    case SamplerComponentType::Stencil:
+        return ctx.U32[4];
+    case SamplerComponentType::Uint:
+        return ctx.U32[4];
+    }
+    throw InvalidArgument("Invalid sampler component type {}", def.component_type);
+}
+
+Id TextureSampleResultToFloat(EmitContext& ctx, const TextureDefinition& def, Id color) {
+    switch (def.component_type) {
+    case SamplerComponentType::Float:
+    case SamplerComponentType::Depth:
+        return color;
+    case SamplerComponentType::Sint:
+        return ctx.OpConvertSToF(ctx.F32[4], color);
+    case SamplerComponentType::Stencil:
+        {
+            const Id converted{ctx.OpConvertUToF(ctx.F32[4], color)};
+            const Id inv255{ctx.Const(1.0f / 255.0f)};
+            const Id scale{ctx.ConstantComposite(ctx.F32[4], inv255, inv255, inv255, inv255)};
+            return ctx.OpFMul(ctx.F32[4], converted, scale);
+        }
+    case SamplerComponentType::Uint:
+        return ctx.OpConvertUToF(ctx.F32[4], color);
+    }
+    throw InvalidArgument("Invalid sampler component type {}", def.component_type);
+}
+
 Id TextureImage(EmitContext& ctx, IR::TextureInstInfo info, const IR::Value& index) {
     if (!index.IsImmediate() || index.U32() != 0) {
         throw NotImplementedException("Indirect image indexing");
@@ -449,31 +485,39 @@ Id EmitBoundImageWrite(EmitContext&) {
 Id EmitImageSampleImplicitLod(EmitContext& ctx, IR::Inst* inst, const IR::Value& index, Id coords,
                               Id bias_lc, const IR::Value& offset) {
     const auto info{inst->Flags<IR::TextureInstInfo>()};
+    const TextureDefinition& def{ctx.textures.at(info.descriptor_index)};
+    const Id color_type{TextureColorResultType(ctx, def)};
+    const Id texture{Texture(ctx, info, index)};
+    Id color{};
     if (ctx.stage == Stage::Fragment) {
         const ImageOperands operands(ctx, info.has_bias != 0, false, info.has_lod_clamp != 0,
                                      bias_lc, offset);
-        return Emit(&EmitContext::OpImageSparseSampleImplicitLod,
+        color = Emit(&EmitContext::OpImageSparseSampleImplicitLod,
-                    &EmitContext::OpImageSampleImplicitLod, ctx, inst, ctx.F32[4],
+                     &EmitContext::OpImageSampleImplicitLod, ctx, inst, color_type, texture,
-                    Texture(ctx, info, index), coords, operands.MaskOptional(), operands.Span());
+                     coords, operands.MaskOptional(), operands.Span());
     } else {
         // We can't use implicit lods on non-fragment stages on SPIR-V. Maxwell hardware behaves as
         // if the lod was explicitly zero.  This may change on Turing with implicit compute
         // derivatives
         const Id lod{ctx.Const(0.0f)};
         const ImageOperands operands(ctx, false, true, info.has_lod_clamp != 0, lod, offset);
-        return Emit(&EmitContext::OpImageSparseSampleExplicitLod,
+        color = Emit(&EmitContext::OpImageSparseSampleExplicitLod,
-                    &EmitContext::OpImageSampleExplicitLod, ctx, inst, ctx.F32[4],
+                     &EmitContext::OpImageSampleExplicitLod, ctx, inst, color_type, texture,
-                    Texture(ctx, info, index), coords, operands.Mask(), operands.Span());
+                     coords, operands.Mask(), operands.Span());
     }
+    return TextureSampleResultToFloat(ctx, def, color);
 }
 
 Id EmitImageSampleExplicitLod(EmitContext& ctx, IR::Inst* inst, const IR::Value& index, Id coords,
                               Id lod, const IR::Value& offset) {
     const auto info{inst->Flags<IR::TextureInstInfo>()};
+    const TextureDefinition& def{ctx.textures.at(info.descriptor_index)};
+    const Id color_type{TextureColorResultType(ctx, def)};
     const ImageOperands operands(ctx, false, true, false, lod, offset);
-    return Emit(&EmitContext::OpImageSparseSampleExplicitLod,
+    const Id color{Emit(&EmitContext::OpImageSparseSampleExplicitLod,
-                &EmitContext::OpImageSampleExplicitLod, ctx, inst, ctx.F32[4],
+                        &EmitContext::OpImageSampleExplicitLod, ctx, inst, color_type,
-                Texture(ctx, info, index), coords, operands.Mask(), operands.Span());
+                        Texture(ctx, info, index), coords, operands.Mask(), operands.Span())};
+    return TextureSampleResultToFloat(ctx, def, color);
 }
 
 Id EmitImageSampleDrefImplicitLod(EmitContext& ctx, IR::Inst* inst, const IR::Value& index,
@@ -509,13 +553,18 @@ Id EmitImageSampleDrefExplicitLod(EmitContext& ctx, IR::Inst* inst, const IR::Va
 Id EmitImageGather(EmitContext& ctx, IR::Inst* inst, const IR::Value& index, Id coords,
                    const IR::Value& offset, const IR::Value& offset2) {
     const auto info{inst->Flags<IR::TextureInstInfo>()};
+    const TextureDefinition& def{ctx.textures.at(info.descriptor_index)};
+    const Id color_type{TextureColorResultType(ctx, def)};
     const ImageOperands operands(ctx, offset, offset2);
+    const Id texture{Texture(ctx, info, index)};
     if (ctx.profile.need_gather_subpixel_offset) {
         coords = ImageGatherSubpixelOffset(ctx, info, TextureImage(ctx, info, index), coords);
     }
-    return Emit(&EmitContext::OpImageSparseGather, &EmitContext::OpImageGather, ctx, inst,
+    const Id color{
-                ctx.F32[4], Texture(ctx, info, index), coords, ctx.Const(info.gather_component),
+        Emit(&EmitContext::OpImageSparseGather, &EmitContext::OpImageGather, ctx, inst, color_type,
-                operands.MaskOptional(), operands.Span());
+             texture, coords, ctx.Const(info.gather_component), operands.MaskOptional(),
+             operands.Span())};
+    return TextureSampleResultToFloat(ctx, def, color);
 }
 
 Id EmitImageGatherDref(EmitContext& ctx, IR::Inst* inst, const IR::Value& index, Id coords,
@@ -533,6 +582,9 @@ Id EmitImageGatherDref(EmitContext& ctx, IR::Inst* inst, const IR::Value& index,
 Id EmitImageFetch(EmitContext& ctx, IR::Inst* inst, const IR::Value& index, Id coords, Id offset,
                   Id lod, Id ms) {
     const auto info{inst->Flags<IR::TextureInstInfo>()};
+    const TextureDefinition* def =
+        info.type == TextureType::Buffer ? nullptr : &ctx.textures.at(info.descriptor_index);
+    const Id result_type{def ? TextureColorResultType(ctx, *def) : ctx.F32[4]};
     AddOffsetToCoordinates(ctx, info, coords, offset);
     if (info.type == TextureType::Buffer) {
         lod = Id{};
@@ -542,8 +594,13 @@ Id EmitImageFetch(EmitContext& ctx, IR::Inst* inst, const IR::Value& index, Id c
         lod = Id{};
     }
     const ImageOperands operands(lod, ms);
-    return Emit(&EmitContext::OpImageSparseFetch, &EmitContext::OpImageFetch, ctx, inst, ctx.F32[4],
+    Id color{Emit(&EmitContext::OpImageSparseFetch, &EmitContext::OpImageFetch, ctx, inst,
-                TextureImage(ctx, info, index), coords, operands.MaskOptional(), operands.Span());
+                  result_type, TextureImage(ctx, info, index), coords, operands.MaskOptional(),
+                  operands.Span())};
+    if (def) {
+        color = TextureSampleResultToFloat(ctx, *def, color);
+    }
+    return color;
 }
 
 Id EmitImageQueryDimensions(EmitContext& ctx, IR::Inst* inst, const IR::Value& index, Id lod,
@@ -588,14 +645,17 @@ Id EmitImageQueryLod(EmitContext& ctx, IR::Inst* inst, const IR::Value& index, I
 Id EmitImageGradient(EmitContext& ctx, IR::Inst* inst, const IR::Value& index, Id coords,
                      Id derivatives, const IR::Value& offset, Id lod_clamp) {
     const auto info{inst->Flags<IR::TextureInstInfo>()};
+    const TextureDefinition& def{ctx.textures.at(info.descriptor_index)};
+    const Id color_type{TextureColorResultType(ctx, def)};
     const auto operands = info.num_derivatives == 3
                               ? ImageOperands(ctx, info.has_lod_clamp != 0, derivatives,
                                               ctx.Def(offset), {}, lod_clamp)
                               : ImageOperands(ctx, info.has_lod_clamp != 0, derivatives,
                                               info.num_derivatives, offset, lod_clamp);
-    return Emit(&EmitContext::OpImageSparseSampleExplicitLod,
+    const Id color{Emit(&EmitContext::OpImageSparseSampleExplicitLod,
-                &EmitContext::OpImageSampleExplicitLod, ctx, inst, ctx.F32[4],
+                        &EmitContext::OpImageSampleExplicitLod, ctx, inst, color_type,
-                Texture(ctx, info, index), coords, operands.Mask(), operands.Span());
+                        Texture(ctx, info, index), coords, operands.Mask(), operands.Span())};
+    return TextureSampleResultToFloat(ctx, def, color);
 }
 
 Id EmitImageRead(EmitContext& ctx, IR::Inst* inst, const IR::Value& index, Id coords) {

src/shader_recompiler/backend/spirv/spirv_emit_context.cpp

@@ -26,28 +26,40 @@ enum class Operation {
     FPMax,
 };
 
-Id ImageType(EmitContext& ctx, const TextureDescriptor& desc) {
+Id ComponentScalarType(EmitContext& ctx, SamplerComponentType component_type) {
+    switch (component_type) {
+    case SamplerComponentType::Float:
+    case SamplerComponentType::Depth:
+        return ctx.F32[1];
+    case SamplerComponentType::Sint:
+    case SamplerComponentType::Stencil:
+        return ctx.S32[1];
+    case SamplerComponentType::Uint:
+        return ctx.U32[1];
+    }
+    throw InvalidArgument("Invalid sampler component type {}", component_type);
+}
+
+Id ImageType(EmitContext& ctx, const TextureDescriptor& desc, Id sampled_type) {
     const spv::ImageFormat format{spv::ImageFormat::Unknown};
-    // Use integer type for integer textures to match the actual texture format
-    const Id type{desc.is_integer ? ctx.U32[1] : ctx.F32[1]};
     const bool depth{desc.is_depth};
     const bool ms{desc.is_multisample};
     switch (desc.type) {
     case TextureType::Color1D:
-        return ctx.TypeImage(type, spv::Dim::Dim1D, depth, false, false, 1, format);
+        return ctx.TypeImage(sampled_type, spv::Dim::Dim1D, depth, false, false, 1, format);
     case TextureType::ColorArray1D:
-        return ctx.TypeImage(type, spv::Dim::Dim1D, depth, true, false, 1, format);
+        return ctx.TypeImage(sampled_type, spv::Dim::Dim1D, depth, true, false, 1, format);
     case TextureType::Color2D:
     case TextureType::Color2DRect:
-        return ctx.TypeImage(type, spv::Dim::Dim2D, depth, false, ms, 1, format);
+        return ctx.TypeImage(sampled_type, spv::Dim::Dim2D, depth, false, ms, 1, format);
     case TextureType::ColorArray2D:
-        return ctx.TypeImage(type, spv::Dim::Dim2D, depth, true, ms, 1, format);
+        return ctx.TypeImage(sampled_type, spv::Dim::Dim2D, depth, true, ms, 1, format);
     case TextureType::Color3D:
-        return ctx.TypeImage(type, spv::Dim::Dim3D, depth, false, false, 1, format);
+        return ctx.TypeImage(sampled_type, spv::Dim::Dim3D, depth, false, false, 1, format);
     case TextureType::ColorCube:
-        return ctx.TypeImage(type, spv::Dim::Cube, depth, false, false, 1, format);
+        return ctx.TypeImage(sampled_type, spv::Dim::Cube, depth, false, false, 1, format);
     case TextureType::ColorArrayCube:
-        return ctx.TypeImage(type, spv::Dim::Cube, depth, true, false, 1, format);
+        return ctx.TypeImage(sampled_type, spv::Dim::Cube, depth, true, false, 1, format);
     case TextureType::Buffer:
         break;
     }
@@ -326,6 +338,9 @@ void DefineSsbos(EmitContext& ctx, StorageTypeDefinition& type_def,
         ctx.Decorate(id, spv::Decoration::Binding, binding);
         ctx.Decorate(id, spv::Decoration::DescriptorSet, 0U);
         ctx.Name(id, fmt::format("ssbo{}", index));
+        if (!desc.is_written) {
+            ctx.Decorate(id, spv::Decoration::NonWritable);
+        }
         if (ctx.profile.supported_spirv >= 0x00010400) {
             ctx.interfaces.push_back(id);
         }
@@ -557,6 +572,7 @@ void EmitContext::DefineCommonTypes(const Info& info) {
 
     output_f32 = Name(TypePointer(spv::StorageClass::Output, F32[1]), "output_f32");
     output_u32 = Name(TypePointer(spv::StorageClass::Output, U32[1]), "output_u32");
+    output_s32 = Name(TypePointer(spv::StorageClass::Output, S32[1]), "output_s32");
 
     if (info.uses_int8 && profile.support_int8) {
         AddCapability(spv::Capability::Int8);
@@ -1370,7 +1386,8 @@ void EmitContext::DefineImageBuffers(const Info& info, u32& binding) {
 void EmitContext::DefineTextures(const Info& info, u32& binding, u32& scaling_index) {
     textures.reserve(info.texture_descriptors.size());
     for (const TextureDescriptor& desc : info.texture_descriptors) {
-        const Id image_type{ImageType(*this, desc)};
+        const Id result_type{ComponentScalarType(*this, desc.component_type)};
+        const Id image_type{ImageType(*this, desc, result_type)};
         const Id sampled_type{TypeSampledImage(image_type)};
         const Id pointer_type{TypePointer(spv::StorageClass::UniformConstant, sampled_type)};
         const Id desc_type{DescType(*this, sampled_type, pointer_type, desc.count)};
@@ -1383,9 +1400,10 @@ void EmitContext::DefineTextures(const Info& info, u32& binding, u32& scaling_in
             .sampled_type = sampled_type,
             .pointer_type = pointer_type,
             .image_type = image_type,
+            .result_type = result_type,
             .count = desc.count,
             .is_multisample = desc.is_multisample,
-            .is_integer = desc.is_integer,
+            .component_type = desc.component_type,
         });
         if (profile.supported_spirv >= 0x00010400) {
             interfaces.push_back(id);
@@ -1444,6 +1462,9 @@ void EmitContext::DefineInputs(const IR::Program& program) {
     }
     if (info.uses_sample_id) {
         sample_id = DefineInput(*this, U32[1], false, spv::BuiltIn::SampleId);
+        if (stage == Stage::Fragment) {
+            Decorate(sample_id, spv::Decoration::Flat);
+        }
     }
     if (info.uses_is_helper_invocation) {
         is_helper_invocation = DefineInput(*this, U1, false, spv::BuiltIn::HelperInvocation);
@@ -1454,6 +1475,13 @@ void EmitContext::DefineInputs(const IR::Program& program) {
         subgroup_mask_le = DefineInput(*this, U32[4], false, spv::BuiltIn::SubgroupLeMaskKHR);
         subgroup_mask_gt = DefineInput(*this, U32[4], false, spv::BuiltIn::SubgroupGtMaskKHR);
         subgroup_mask_ge = DefineInput(*this, U32[4], false, spv::BuiltIn::SubgroupGeMaskKHR);
+        if (stage == Stage::Fragment) {
+            Decorate(subgroup_mask_eq, spv::Decoration::Flat);
+            Decorate(subgroup_mask_lt, spv::Decoration::Flat);
+            Decorate(subgroup_mask_le, spv::Decoration::Flat);
+            Decorate(subgroup_mask_gt, spv::Decoration::Flat);
+            Decorate(subgroup_mask_ge, spv::Decoration::Flat);
+        }
     }
     if (info.uses_fswzadd || info.uses_subgroup_invocation_id || info.uses_subgroup_shuffles ||
         (profile.warp_size_potentially_larger_than_guest &&
@@ -1461,7 +1489,9 @@ void EmitContext::DefineInputs(const IR::Program& program) {
         AddCapability(spv::Capability::GroupNonUniform);
         subgroup_local_invocation_id =
             DefineInput(*this, U32[1], false, spv::BuiltIn::SubgroupLocalInvocationId);
-        Decorate(subgroup_local_invocation_id, spv::Decoration::Flat);
+        if (stage == Stage::Fragment) {
+            Decorate(subgroup_local_invocation_id, spv::Decoration::Flat);
+        }
     }
     if (info.uses_fswzadd) {
         const Id f32_one{Const(1.0f)};
@@ -1473,6 +1503,9 @@ void EmitContext::DefineInputs(const IR::Program& program) {
     }
     if (loads[IR::Attribute::PrimitiveId]) {
         primitive_id = DefineInput(*this, U32[1], false, spv::BuiltIn::PrimitiveId);
+        if (stage == Stage::Fragment) {
+            Decorate(primitive_id, spv::Decoration::Flat);
+        }
     }
     if (loads[IR::Attribute::Layer]) {
         AddCapability(spv::Capability::Geometry);
@@ -1564,17 +1597,21 @@ void EmitContext::DefineInputs(const IR::Program& program) {
         if (stage != Stage::Fragment) {
             continue;
         }
-        switch (info.interpolation[index]) {
+        const bool is_integer = input_type == AttributeType::SignedInt ||
-        case Interpolation::Smooth:
+                                input_type == AttributeType::UnsignedInt;
-            // Default
+        if (is_integer) {
-            // Decorate(id, spv::Decoration::Smooth);
-            break;
-        case Interpolation::NoPerspective:
-            Decorate(id, spv::Decoration::NoPerspective);
-            break;
-        case Interpolation::Flat:
             Decorate(id, spv::Decoration::Flat);
-            break;
+        } else {
+            switch (info.interpolation[index]) {
+            case Interpolation::Smooth:
+                break;
+            case Interpolation::NoPerspective:
+                Decorate(id, spv::Decoration::NoPerspective);
+                break;
+            case Interpolation::Flat:
+                Decorate(id, spv::Decoration::Flat);
+                break;
+            }
         }
     }
     if (stage == Stage::TessellationEval) {

src/shader_recompiler/backend/spirv/spirv_emit_context.h

@@ -35,9 +35,10 @@ struct TextureDefinition {
     Id sampled_type;
     Id pointer_type;
     Id image_type;
+    Id result_type;
     u32 count;
     bool is_multisample;
-    bool is_integer;
+    SamplerComponentType component_type;
 };
 
 struct TextureBufferDefinition {
@@ -244,6 +245,7 @@ public:
 
     Id output_f32{};
     Id output_u32{};
+    Id output_s32{};
 
     Id image_buffer_type{};
     Id image_u32{};