gl_shader_gen: Implement fragment lighting fresnel effect.

src/video_core/pica.h

@@ -713,12 +713,15 @@ struct Regs {
         }
     };
 
+    /// Returns true if the specified lighting sampler is supported by the current Pica lighting configuration
     static bool IsLightingSamplerSupported(LightingConfig config, LightingSampler sampler) {
         switch (sampler) {
         case LightingSampler::Distribution0:
             return (config != LightingConfig::Config1);
         case LightingSampler::Distribution1:
             return (config != LightingConfig::Config0) && (config != LightingConfig::Config1) && (config != LightingConfig::Config5);
+        case LightingSampler::Fresnel:
+            return (config != LightingConfig::Config0) && (config != LightingConfig::Config2) && (config != LightingConfig::Config4);
         }
         return false;
     }
@@ -761,6 +764,7 @@ struct Regs {
         BitField<0, 3, u32> src_num; // number of enabled lights - 1
 
         union {
+            BitField< 2, 2, LightingFresnelSelector> fresnel_selector;
             BitField< 4, 4, LightingConfig> config;
             BitField<27, 1, u32> clamp_highlights; // 1: GL_TRUE, 0: GL_FALSE
         };
@@ -768,6 +772,7 @@ struct Regs {
         union {
             BitField<16, 1, u32> lut_enable_d0; // 0: GL_TRUE, 1: GL_FALSE
             BitField<17, 1, u32> lut_enable_d1; // 0: GL_TRUE, 1: GL_FALSE
+            BitField<19, 1, u32> lut_enable_fr; // 0: GL_TRUE, 1: GL_FALSE
 
             // Each bit specifies whether distance attenuation should be applied for the
             // corresponding light

src/video_core/renderer_opengl/gl_rasterizer.h

@@ -97,7 +97,13 @@ struct PicaShaderConfig {
         res.lighting.lut_d1.type = (Pica::Regs::LightingLutInput)regs.lighting.lut_input.d1.Value();
         res.lighting.lut_d1.scale = regs.lighting.lut_scale.GetScale(regs.lighting.lut_scale.d1);
 
+        res.lighting.lut_fr.enable = regs.lighting.lut_enable_fr == 0;
+        res.lighting.lut_fr.abs_input = regs.lighting.abs_lut_input.fr == 0;
+        res.lighting.lut_fr.type = (Pica::Regs::LightingLutInput)regs.lighting.lut_input.fr.Value();
+        res.lighting.lut_fr.scale = regs.lighting.lut_scale.GetScale(regs.lighting.lut_scale.fr);
+
         res.lighting.config = regs.lighting.config;
+        res.lighting.fresnel_selector = regs.lighting.fresnel_selector;
         res.lighting.clamp_highlights = regs.lighting.clamp_highlights != 0;
 
         return res;
@@ -134,6 +140,7 @@ struct PicaShaderConfig {
             unsigned src_num = 0;
             bool clamp_highlights = false;
             Pica::Regs::LightingConfig config = Pica::Regs::LightingConfig::Config0;
+            Pica::Regs::LightingFresnelSelector fresnel_selector = Pica::Regs::LightingFresnelSelector::None;
 
             struct {
                 bool enable = false;

src/video_core/renderer_opengl/gl_shader_gen.cpp

@@ -321,8 +321,8 @@ static void WriteTevStage(std::string& out, const PicaShaderConfig& config, unsi
 /// Writes the code to emulate fragment lighting
 static void WriteLighting(std::string& out, const PicaShaderConfig& config) {
     // Define lighting globals
-    out += "vec3 diffuse_sum = vec3(0.0);\n";
+    out += "vec4 diffuse_sum = vec4(0.0, 0.0, 0.0, 1.0);\n";
-    out += "vec3 specular_sum = vec3(0.0);\n";
+    out += "vec4 specular_sum = vec4(0.0, 0.0, 0.0, 1.0);\n";
     out += "vec3 light_vector = vec3(0.0);\n";
 
     // Convert interpolated quaternion to a GL fragment normal
@@ -402,9 +402,6 @@ static void WriteLighting(std::string& out, const PicaShaderConfig& config) {
             dist_atten = GetLutValue((Regs::LightingSampler)lut_num, lut_index);
         }
 
-        // Compute primary fragment color (diffuse lighting) function
-        out += "diffuse_sum += ((" + light_src + ".diffuse * " + dot_product + ") + " + light_src + ".ambient) * " + dist_atten + ";\n";
-
         // If enabled, clamp specular component if lighting result is negative
         std::string clamp_highlights = config.lighting.clamp_highlights ? "(dot(light_vector, normal) <= 0.0 ? 0.0 : 1.0)" : "1.0";
 
@@ -426,14 +423,34 @@ static void WriteLighting(std::string& out, const PicaShaderConfig& config) {
         }
         std::string specular_1 = "(" + d1_lut_value + " * " + light_src + ".specular_1)";
 
+        // Fresnel
+        if (config.lighting.lut_fr.enable && Pica::Regs::IsLightingSamplerSupported(config.lighting.config, Pica::Regs::LightingSampler::Fresnel)) {
+            // Lookup fresnel LUT value
+            std::string fr_lut_index = GetLutIndex(light_config.num, config.lighting.lut_fr.type, config.lighting.lut_fr.abs_input);
+            std::string fr_lut_value = "(" + std::to_string(config.lighting.lut_fr.scale) + " * " + GetLutValue(Regs::LightingSampler::Fresnel, fr_lut_index) + ")";
+
+            // Enabled for difffuse lighting alpha component
+            if (config.lighting.fresnel_selector == Pica::Regs::LightingFresnelSelector::PrimaryAlpha ||
+                config.lighting.fresnel_selector == Pica::Regs::LightingFresnelSelector::BothAlpha)
+                out += "diffuse_sum.a  *= " + fr_lut_value + ";\n";
+
+            // Enabled for the specular lighting alpha component
+            if (config.lighting.fresnel_selector == Pica::Regs::LightingFresnelSelector::SecondaryAlpha ||
+                config.lighting.fresnel_selector == Pica::Regs::LightingFresnelSelector::BothAlpha)
+                out += "specular_sum.a *= " + fr_lut_value + ";\n";
+        }
+
+        // Compute primary fragment color (diffuse lighting) function
+        out += "diffuse_sum.rgb += ((" + light_src + ".diffuse * " + dot_product + ") + " + light_src + ".ambient) * " + dist_atten + ";\n";
+
         // Compute secondary fragment color (specular lighting) function
-        out += "specular_sum += (" + specular_0 + " + " + specular_1 + ") * " + clamp_highlights + " * " + dist_atten + ";\n";
+        out += "specular_sum.rgb += (" + specular_0 + " + " + specular_1 + ") * " + clamp_highlights + " * " + dist_atten + ";\n";
     }
 
     // Sum final lighting result
-    out += "diffuse_sum += lighting_global_ambient;\n";
+    out += "diffuse_sum.rgb += lighting_global_ambient;\n";
-    out += "primary_fragment_color = vec4(clamp(diffuse_sum, vec3(0.0), vec3(1.0)), 1.0);\n";
+    out += "primary_fragment_color = clamp(diffuse_sum, vec4(0.0), vec4(1.0));\n";
-    out += "secondary_fragment_color = vec4(clamp(specular_sum, vec3(0.0), vec3(1.0)), 1.0);\n";
+    out += "secondary_fragment_color = clamp(specular_sum, vec4(0.0), vec4(1.0));\n";
 }
 
 std::string GenerateFragmentShader(const PicaShaderConfig& config) {