video_core: Perform quaternion correction and interpolation in fragment shader using barycentric extension. (#7126)

src/video_core/renderer_opengl/gl_rasterizer.cpp

@@ -280,7 +280,15 @@ bool RasterizerOpenGL::SetupGeometryShader() {
         return false;
     }
 
+    // Enable the quaternion fix-up geometry-shader only if we are actually doing per-fragment
+    // lighting and care about proper quaternions. Otherwise just use standard vertex+fragment
+    // shaders
+    if (regs.lighting.disable) {
+        shader_manager.UseTrivialGeometryShader();
+    } else {
         shader_manager.UseFixedGeometryShader(regs);
+    }
+
     return true;
 }
 

src/video_core/renderer_opengl/gl_shader_manager.cpp

@@ -88,7 +88,12 @@ static std::tuple<PicaVSConfig, Pica::Shader::ShaderSetup> BuildVSConfigFromRaw(
     Pica::Shader::ShaderSetup setup;
     setup.program_code = program_code;
     setup.swizzle_data = swizzle_data;
-    return {PicaVSConfig{raw.GetRawShaderConfig(), setup, driver.HasClipCullDistance(), true},
+
+    // Enable the geometry-shader only if we are actually doing per-fragment lighting
+    // and care about proper quaternions. Otherwise just use standard vertex+fragment shaders
+    const bool use_geometry_shader = !raw.GetRawShaderConfig().lighting.disable;
+    return {PicaVSConfig{raw.GetRawShaderConfig(), setup, driver.HasClipCullDistance(),
+                         use_geometry_shader},
             setup};
 }
 
@@ -265,6 +270,7 @@ public:
             .has_geometry_shader = true,
             .has_custom_border_color = true,
             .has_fragment_shader_interlock = false,
+            .has_fragment_shader_barycentric = false,
             .has_blend_minmax_factor = driver.HasBlendMinMaxFactor(),
             .has_minus_one_to_one_range = true,
             .has_logic_op = !driver.IsOpenGLES(),
@@ -272,6 +278,8 @@ public:
             .has_gl_arm_framebuffer_fetch = driver.HasArmShaderFramebufferFetch(),
             .has_gl_nv_fragment_shader_interlock = driver.GetVendor() == Vendor::Nvidia,
             .has_gl_intel_fragment_shader_interlock = driver.GetVendor() == Vendor::Intel,
+            // TODO: This extension requires GLSL 450 / OpenGL 4.5 context.
+            .has_gl_nv_fragment_shader_barycentric = false,
             .is_vulkan = false,
         };
     }
@@ -327,7 +335,11 @@ ShaderProgramManager::~ShaderProgramManager() = default;
 
 bool ShaderProgramManager::UseProgrammableVertexShader(const Pica::Regs& regs,
                                                        Pica::Shader::ShaderSetup& setup) {
-    PicaVSConfig config{regs, setup, driver.HasClipCullDistance(), true};
+    // Enable the geometry-shader only if we are actually doing per-fragment lighting
+    // and care about proper quaternions. Otherwise just use standard vertex+fragment shaders
+    const bool use_geometry_shader = !regs.lighting.disable;
+
+    PicaVSConfig config{regs, setup, driver.HasClipCullDistance(), use_geometry_shader};
     auto [handle, result] = impl->programmable_vertex_shaders.Get(config, setup);
     if (handle == 0)
         return false;

src/video_core/renderer_vulkan/vk_instance.cpp

@@ -403,7 +403,8 @@ bool Instance::CreateDevice() {
         vk::PhysicalDeviceTimelineSemaphoreFeaturesKHR,
         vk::PhysicalDeviceCustomBorderColorFeaturesEXT, vk::PhysicalDeviceIndexTypeUint8FeaturesEXT,
         vk::PhysicalDeviceFragmentShaderInterlockFeaturesEXT,
-        vk::PhysicalDevicePipelineCreationCacheControlFeaturesEXT>();
+        vk::PhysicalDevicePipelineCreationCacheControlFeaturesEXT,
+        vk::PhysicalDeviceFragmentShaderBarycentricFeaturesKHR>();
     const vk::StructureChain properties_chain =
         physical_device.getProperties2<vk::PhysicalDeviceProperties2,
                                        vk::PhysicalDevicePortabilitySubsetPropertiesKHR>();
@@ -436,6 +437,7 @@ bool Instance::CreateDevice() {
     };
 
     const bool is_nvidia = driver_id == vk::DriverIdKHR::eNvidiaProprietary;
+    const bool is_moltenvk = driver_id == vk::DriverIdKHR::eMoltenvk;
     const bool is_arm = driver_id == vk::DriverIdKHR::eArmProprietary;
     const bool is_qualcomm = driver_id == vk::DriverIdKHR::eQualcommProprietary;
 
@@ -459,6 +461,9 @@ bool Instance::CreateDevice() {
     const bool has_pipeline_creation_cache_control =
         add_extension(VK_EXT_PIPELINE_CREATION_CACHE_CONTROL_EXTENSION_NAME, is_nvidia,
                       "it is broken on Nvidia drivers");
+    const bool has_fragment_shader_barycentric =
+        add_extension(VK_KHR_FRAGMENT_SHADER_BARYCENTRIC_EXTENSION_NAME, is_moltenvk,
+                      "the PerVertexKHR attribute is not supported by MoltenVK");
 
     const auto family_properties = physical_device.getQueueFamilyProperties();
     if (family_properties.empty()) {
@@ -514,6 +519,7 @@ bool Instance::CreateDevice() {
         vk::PhysicalDeviceIndexTypeUint8FeaturesEXT{},
         vk::PhysicalDeviceFragmentShaderInterlockFeaturesEXT{},
         vk::PhysicalDevicePipelineCreationCacheControlFeaturesEXT{},
+        vk::PhysicalDeviceFragmentShaderBarycentricFeaturesKHR{},
     };
 
 #define PROP_GET(structName, prop, property) property = properties_chain.get<structName>().prop;
@@ -581,6 +587,13 @@ bool Instance::CreateDevice() {
         device_chain.unlink<vk::PhysicalDevicePipelineCreationCacheControlFeaturesEXT>();
     }
 
+    if (has_fragment_shader_barycentric) {
+        FEAT_SET(vk::PhysicalDeviceFragmentShaderBarycentricFeaturesKHR, fragmentShaderBarycentric,
+                 fragment_shader_barycentric)
+    } else {
+        device_chain.unlink<vk::PhysicalDeviceFragmentShaderBarycentricFeaturesKHR>();
+    }
+
 #undef PROP_GET
 #undef FEAT_SET
 

src/video_core/renderer_vulkan/vk_instance.h

@@ -168,6 +168,11 @@ public:
         return shader_stencil_export;
     }
 
+    /// Returns true when VK_KHR_fragment_shader_barycentric is supported
+    bool IsFragmentShaderBarycentricSupported() const {
+        return fragment_shader_barycentric;
+    }
+
     /// Returns the vendor ID of the physical device
     u32 GetVendorID() const {
         return properties.vendorID;
@@ -307,6 +312,7 @@ private:
     bool fragment_shader_interlock{};
     bool image_format_list{};
     bool pipeline_creation_cache_control{};
+    bool fragment_shader_barycentric{};
     bool shader_stencil_export{};
     bool tooling_info{};
     bool debug_utils_supported{};

src/video_core/renderer_vulkan/vk_pipeline_cache.cpp

@@ -96,6 +96,7 @@ PipelineCache::PipelineCache(const Instance& instance_, Scheduler& scheduler_,
         .has_geometry_shader = instance.UseGeometryShaders(),
         .has_custom_border_color = instance.IsCustomBorderColorSupported(),
         .has_fragment_shader_interlock = instance.IsFragmentShaderInterlockSupported(),
+        .has_fragment_shader_barycentric = instance.IsFragmentShaderBarycentricSupported(),
         .has_blend_minmax_factor = false,
         .has_minus_one_to_one_range = false,
         .has_logic_op = !instance.NeedsLogicOpEmulation(),
@@ -331,8 +332,13 @@ bool PipelineCache::BindPipeline(const PipelineInfo& info, bool wait_built) {
 bool PipelineCache::UseProgrammableVertexShader(const Pica::Regs& regs,
                                                 Pica::Shader::ShaderSetup& setup,
                                                 const VertexLayout& layout) {
-    PicaVSConfig config{regs, setup, instance.IsShaderClipDistanceSupported(),
+    // Enable the geometry-shader only if we are actually doing per-fragment lighting
-                        instance.UseGeometryShaders()};
+    // and care about proper quaternions. Otherwise just use standard vertex+fragment shaders.
+    // We also don't need the geometry shader if we have the barycentric extension.
+    const bool use_geometry_shader = instance.UseGeometryShaders() && !regs.lighting.disable &&
+                                     !instance.IsFragmentShaderBarycentricSupported();
+
+    PicaVSConfig config{regs, setup, instance.IsShaderClipDistanceSupported(), use_geometry_shader};
 
     for (u32 i = 0; i < layout.attribute_count; i++) {
         const VertexAttribute& attr = layout.attributes[i];

src/video_core/renderer_vulkan/vk_rasterizer.cpp

@@ -337,6 +337,14 @@ bool RasterizerVulkan::SetupGeometryShader() {
         return false;
     }
 
+    // Enable the quaternion fix-up geometry-shader only if we are actually doing per-fragment
+    // lighting and care about proper quaternions. Otherwise just use standard vertex+fragment
+    // shaders. We also don't need a geometry shader if the barycentric extension is supported.
+    if (regs.lighting.disable || instance.IsFragmentShaderBarycentricSupported()) {
+        pipeline_cache.UseTrivialGeometryShader();
+        return true;
+    }
+
     return pipeline_cache.UseFixedGeometryShader(regs);
 }
 

src/video_core/shader/generator/glsl_fs_shader_gen.cpp

@@ -567,6 +567,17 @@ void FragmentModule::WriteLighting() {
         }
     }
 
+    // If the barycentric extension is enabled, perform quaternion correction here.
+    if (use_fragment_shader_barycentric) {
+        out += "vec4 normquat_0 = normquats[0];\n"
+               "vec4 normquat_1 = mix(normquats[1], -normquats[1], "
+               "bvec4(AreQuaternionsOpposite(normquats[0], normquats[1])));\n"
+               "vec4 normquat_2 = mix(normquats[2], -normquats[2], "
+               "bvec4(AreQuaternionsOpposite(normquats[0], normquats[2])));\n"
+               "vec4 normquat = gl_BaryCoord.x * normquat_0 + gl_BaryCoord.y * normquat_1 + "
+               "gl_BaryCoord.z * normquat_2;\n";
+    }
+
     // Rotate the surface-local normal by the interpolated normal quaternion to convert it to
     // eyespace.
     out += "vec4 normalized_normquat = normalize(normquat);\n"
@@ -1231,6 +1242,20 @@ void FragmentModule::DefineExtensions() {
             use_fragment_shader_interlock = false;
         }
     }
+    if (config.lighting.enable) {
+        use_fragment_shader_barycentric = true;
+        if (profile.has_fragment_shader_barycentric) {
+            out += "#extension GL_EXT_fragment_shader_barycentric : enable\n";
+            out += "#define pervertex pervertexEXT\n";
+            out += "#define gl_BaryCoord gl_BaryCoordEXT\n";
+        } else if (profile.has_gl_nv_fragment_shader_barycentric) {
+            out += "#extension GL_NV_fragment_shader_barycentric : enable\n";
+            out += "#define pervertex pervertexNV\n";
+            out += "#define gl_BaryCoord gl_BaryCoordNV\n";
+        } else {
+            use_fragment_shader_barycentric = false;
+        }
+    }
     if (config.EmulateBlend()) {
         if (profile.has_gl_ext_framebuffer_fetch) {
             out += "#extension GL_EXT_shader_framebuffer_fetch : enable\n";
@@ -1263,7 +1288,11 @@ void FragmentModule::DefineInterface() {
     define_input("vec2 texcoord1", Semantic::Texcoord1);
     define_input("vec2 texcoord2", Semantic::Texcoord2);
     define_input("float texcoord0_w", Semantic::Texcoord0_W);
+    if (use_fragment_shader_barycentric) {
+        define_input("pervertex vec4 normquats[]", Semantic::Normquat);
+    } else {
         define_input("vec4 normquat", Semantic::Normquat);
+    }
     define_input("vec3 view", Semantic::View);
 
     // Output attributes
@@ -1360,6 +1389,14 @@ float LookupLightingLUTSigned(int lut_index, float pos) {
     return LookupLightingLUT(lut_index, index, delta);
 }
 )";
+
+    if (use_fragment_shader_barycentric) {
+        out += R"(
+bool AreQuaternionsOpposite(vec4 qa, vec4 qb) {
+    return (dot(qa, qb) < 0.0);
+}
+)";
+    }
 }
 
 void FragmentModule::DefineShadowHelpers() {

src/video_core/shader/generator/glsl_fs_shader_gen.h

@@ -87,6 +87,7 @@ private:
     std::string out;
     bool use_blend_fallback{};
     bool use_fragment_shader_interlock{};
+    bool use_fragment_shader_barycentric{};
 };
 
 /**

src/video_core/shader/generator/profile.h

@@ -12,6 +12,7 @@ struct Profile {
     bool has_geometry_shader{};
     bool has_custom_border_color{};
     bool has_fragment_shader_interlock{};
+    bool has_fragment_shader_barycentric{};
     bool has_blend_minmax_factor{};
     bool has_minus_one_to_one_range{};
     bool has_logic_op{};
@@ -19,6 +20,7 @@ struct Profile {
     bool has_gl_arm_framebuffer_fetch{};
     bool has_gl_nv_fragment_shader_interlock{};
     bool has_gl_intel_fragment_shader_interlock{};
+    bool has_gl_nv_fragment_shader_barycentric{};
     bool is_vulkan{};
 };