From dbd882ddeb1a1a9233c0085d0b8ccb022db385b2 Mon Sep 17 00:00:00 2001
From: ReinUsesLisp <reinuseslisp@airmail.cc>
Date: Sat, 27 Mar 2021 04:59:58 -0300
Subject: shader: Better interpolation and disabled attributes support

---
 .../backend/spirv/emit_context.cpp                 | 29 +++++++++++++++++++---
 .../backend/spirv/emit_spirv_context_get_set.cpp   | 29 +++++++++++++++-------
 2 files changed, 46 insertions(+), 12 deletions(-)

(limited to 'src/shader_recompiler/backend/spirv')

diff --git a/src/shader_recompiler/backend/spirv/emit_context.cpp b/src/shader_recompiler/backend/spirv/emit_context.cpp
index 4d5dabcbf..a8ca33c1d 100644
--- a/src/shader_recompiler/backend/spirv/emit_context.cpp
+++ b/src/shader_recompiler/backend/spirv/emit_context.cpp
@@ -76,6 +76,8 @@ Id GetAttributeType(EmitContext& ctx, AttributeType type) {
         return ctx.TypeVector(ctx.TypeInt(32, true), 4);
     case AttributeType::UnsignedInt:
         return ctx.U32[4];
+    case AttributeType::Disabled:
+        break;
     }
     throw InvalidArgument("Invalid attribute type {}", type);
 }
@@ -305,15 +307,36 @@ void EmitContext::DefineInputs(const Info& info) {
     if (info.loads_front_face) {
         front_face = DefineInput(*this, U1, spv::BuiltIn::FrontFacing);
     }
-    for (size_t index = 0; index < info.loads_generics.size(); ++index) {
-        if (!info.loads_generics[index]) {
+    for (size_t index = 0; index < info.input_generics.size(); ++index) {
+        const InputVarying generic{info.input_generics[index]};
+        if (!generic.used) {
             continue;
         }
-        const Id type{GetAttributeType(*this, profile.generic_input_types[index])};
+        const AttributeType input_type{profile.generic_input_types[index]};
+        if (input_type == AttributeType::Disabled) {
+            continue;
+        }
+        const Id type{GetAttributeType(*this, input_type)};
         const Id id{DefineInput(*this, type)};
         Decorate(id, spv::Decoration::Location, static_cast<u32>(index));
         Name(id, fmt::format("in_attr{}", index));
         input_generics[index] = id;
+
+        if (stage != Stage::Fragment) {
+            continue;
+        }
+        switch (generic.interpolation) {
+        case Interpolation::Smooth:
+            // Default
+            // Decorate(id, spv::Decoration::Smooth);
+            break;
+        case Interpolation::NoPerspective:
+            Decorate(id, spv::Decoration::NoPerspective);
+            break;
+        case Interpolation::Flat:
+            Decorate(id, spv::Decoration::Flat);
+            break;
+        }
     }
 }
 
diff --git a/src/shader_recompiler/backend/spirv/emit_spirv_context_get_set.cpp b/src/shader_recompiler/backend/spirv/emit_spirv_context_get_set.cpp
index 6fa16eb80..4cbc2aec1 100644
--- a/src/shader_recompiler/backend/spirv/emit_spirv_context_get_set.cpp
+++ b/src/shader_recompiler/backend/spirv/emit_spirv_context_get_set.cpp
@@ -10,16 +10,23 @@
 
 namespace Shader::Backend::SPIRV {
 namespace {
-std::tuple<Id, Id, bool> AttrTypes(EmitContext& ctx, u32 index) {
-    const bool is_first_reader{ctx.stage == Stage::VertexB};
+struct AttrInfo {
+    Id pointer;
+    Id id;
+    bool needs_cast;
+};
+
+std::optional<AttrInfo> AttrTypes(EmitContext& ctx, u32 index) {
     const AttributeType type{ctx.profile.generic_input_types.at(index)};
     switch (type) {
     case AttributeType::Float:
-        return {ctx.input_f32, ctx.F32[1], false};
+        return AttrInfo{ctx.input_f32, ctx.F32[1], false};
     case AttributeType::UnsignedInt:
-        return {ctx.input_u32, ctx.U32[1], true};
+        return AttrInfo{ctx.input_u32, ctx.U32[1], true};
     case AttributeType::SignedInt:
-        return {ctx.input_s32, ctx.TypeInt(32, true), true};
+        return AttrInfo{ctx.input_s32, ctx.TypeInt(32, true), true};
+    case AttributeType::Disabled:
+        return std::nullopt;
     }
     throw InvalidArgument("Invalid attribute type {}", type);
 }
@@ -129,11 +136,15 @@ Id EmitGetAttribute(EmitContext& ctx, IR::Attribute attr) {
     const auto element_id{[&] { return ctx.Constant(ctx.U32[1], element); }};
     if (IR::IsGeneric(attr)) {
         const u32 index{IR::GenericAttributeIndex(attr)};
-        const auto [pointer_type, type, needs_cast]{AttrTypes(ctx, index)};
+        const std::optional<AttrInfo> type{AttrTypes(ctx, index)};
+        if (!type) {
+            // Attribute is disabled
+            return ctx.Constant(ctx.F32[1], 0.0f);
+        }
         const Id generic_id{ctx.input_generics.at(index)};
-        const Id pointer{ctx.OpAccessChain(pointer_type, generic_id, element_id())};
-        const Id value{ctx.OpLoad(type, pointer)};
-        return needs_cast ? ctx.OpBitcast(ctx.F32[1], value) : value;
+        const Id pointer{ctx.OpAccessChain(type->pointer, generic_id, element_id())};
+        const Id value{ctx.OpLoad(type->id, pointer)};
+        return type->needs_cast ? ctx.OpBitcast(ctx.F32[1], value) : value;
     }
     switch (attr) {
     case IR::Attribute::PositionX:
-- 
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