renderer_opengl: Implement HW fragment lighting distance attenuation.

src/video_core/renderer_opengl/gl_rasterizer.h

@@ -78,9 +78,13 @@ struct PicaShaderConfig {
 
         for (unsigned light_index = 0; light_index < res.num_lights; ++light_index) {
             unsigned num = regs.lighting.light_enable.GetNum(light_index);
+            const auto& light = regs.lighting.light[num];
             res.light_src[light_index].num = num;
-            res.light_src[light_index].directional = regs.lighting.light[num].w;
-            res.light_src[light_index].two_sided_diffuse = regs.lighting.light[num].two_sided_diffuse;
+            res.light_src[light_index].directional = light.w;
+            res.light_src[light_index].two_sided_diffuse = light.two_sided_diffuse;
+            res.light_src[light_index].dist_atten_enabled = regs.lighting.dist_atten_enable.IsEnabled(num);
+            res.light_src[light_index].dist_atten_bias = Pica::float20::FromRawFloat20(light.dist_atten_bias).ToFloat32();
+            res.light_src[light_index].dist_atten_scale = Pica::float20::FromRawFloat20(light.dist_atten_scale).ToFloat32();
         }
 
         return res;
@@ -98,19 +102,23 @@ struct PicaShaderConfig {
         return std::memcmp(this, &o, sizeof(PicaShaderConfig)) == 0;
     };
 
-    Pica::Regs::CompareFunc alpha_test_func;
-    std::array<Pica::Regs::TevStageConfig, 6> tev_stages = {};
-    u8 combiner_buffer_input;
-
     struct {
-        unsigned num;
-        bool directional;
-        bool two_sided_diffuse;
-        bool dist_atten_enabled;
-    } light_src[8];
-
-    bool lighting_enabled;
-    unsigned num_lights;
+        Pica::Regs::CompareFunc alpha_test_func = Pica::Regs::CompareFunc::Never;
+        std::array<Pica::Regs::TevStageConfig, 6> tev_stages = {};
+        u8 combiner_buffer_input = 0;
+
+        struct {
+            unsigned num = 0;
+            bool directional = false;
+            bool two_sided_diffuse = false;
+            bool dist_atten_enabled = false;
+            GLfloat dist_atten_scale = 0.0f;
+            GLfloat dist_atten_bias = 0.0f;
+        } light_src[8];
+
+        bool lighting_enabled = false;
+        unsigned num_lights = 0;
+    };
 };
 
 namespace std {

src/video_core/renderer_opengl/gl_shader_gen.cpp

@@ -371,12 +371,13 @@ vec4 primary_fragment_color = vec4(0.0);
 
         for (unsigned light_index = 0; light_index < config.num_lights; ++light_index) {
             unsigned num = config.light_src[light_index].num;
+            std::string light_src = "light_src[" + std::to_string(num) + "]";
 
             std::string light_vector;
             if (config.light_src[light_index].directional)
-                light_vector = "normalize(-light_src[" + std::to_string(num) + "].position)";
+                light_vector = "normalize(-" + light_src + ".position)";
             else
-                light_vector = "normalize(light_src[" + std::to_string(num) + "].position - fragment_position)";
+                light_vector = "normalize(" + light_src + ".position - fragment_position)";
 
             std::string dot_product;
             if (config.light_src[light_index].two_sided_diffuse)
@@ -384,7 +385,19 @@ vec4 primary_fragment_color = vec4(0.0);
             else
                 dot_product = "max(dot(" + light_vector + ", normal), 0.0)";
 
-            out += "diffuse_sum += ((light_src[" + std::to_string(num) + "].diffuse * " + dot_product + ") + light_src[" + std::to_string(num) + "].ambient) * 1.0;\n";
+            std::string dist_atten = "1.0";
+            if (config.light_src[light_index].dist_atten_enabled) {
+                std::string scale = std::to_string(config.light_src[light_index].dist_atten_scale);
+                std::string bias = std::to_string(config.light_src[light_index].dist_atten_bias);
+                std::string lut_index = "(" + scale + " * length(fragment_position - " + light_src + ".position) + " + bias + ")";
+                std::string clamped_lut_index = "((clamp(int(" + lut_index + " * 256.0), 0, 255)))";
+
+                unsigned lut_num = ((unsigned)Regs::LightingSampler::DistanceAttenuation + num);
+
+                dist_atten = "lighting_lut_" + std::to_string(lut_num /4) + "[" + clamped_lut_index + "][" + std::to_string(lut_num & 3) + "]";
+            }
+
+            out += "diffuse_sum += ((light_src[" + std::to_string(num) + "].diffuse * " + dot_product + ") + light_src[" + std::to_string(num) + "].ambient) * " + dist_atten + ";\n";
         }
 
         out += "diffuse_sum += lighting_global_ambient;\n";