gl_rasterizer: Initial implementation of bump mapping.

src/video_core/pica.h

@@ -702,6 +702,12 @@ struct Regs {
         LN = 3, // Cosine of the angle between the light and the normal vectors
     };
 
+    enum class LightingBumpMode : u32 {
+        None = 0,
+        NormalMap = 1,
+        TangentMap = 2,
+    };
+
     union LightColor {
         BitField< 0, 10, u32> b;
         BitField<10, 10, u32> g;
@@ -775,7 +781,10 @@ struct Regs {
         union {
             BitField< 2, 2, LightingFresnelSelector> fresnel_selector;
             BitField< 4, 4, LightingConfig> config;
+            BitField<22, 2, u32> bump_selector; // 0: Texture 0, 1: Texture 1, 2: Texture 2
             BitField<27, 1, u32> clamp_highlights; // 1: GL_TRUE, 0: GL_FALSE
+            BitField<28, 2, LightingBumpMode> bump_mode; // 1: GL_TRUE, 0: GL_FALSE
+            BitField<30, 1, u32> bump_renorm; // 0: GL_TRUE, 1: GL_FALSE
         };
 
         union {

src/video_core/renderer_opengl/gl_rasterizer.h

@@ -119,6 +119,9 @@ struct PicaShaderConfig {
 
         res.lighting.config = regs.lighting.config;
         res.lighting.fresnel_selector = regs.lighting.fresnel_selector;
+        res.lighting.bump_mode = regs.lighting.bump_mode;
+        res.lighting.bump_selector = regs.lighting.bump_selector;
+        res.lighting.bump_renorm = regs.lighting.bump_renorm == 0;
         res.lighting.clamp_highlights = regs.lighting.clamp_highlights != 0;
 
         return res;
@@ -153,6 +156,9 @@ struct PicaShaderConfig {
 
             bool enable = false;
             unsigned src_num = 0;
+            Pica::Regs::LightingBumpMode bump_mode = Pica::Regs::LightingBumpMode::None;
+            unsigned bump_selector = 0;
+            bool bump_renorm = false;
             bool clamp_highlights = false;
 
             Pica::Regs::LightingConfig config = Pica::Regs::LightingConfig::Config0;

src/video_core/renderer_opengl/gl_shader_gen.cpp

@@ -326,11 +326,28 @@ static void WriteLighting(std::string& out, const PicaShaderConfig& config) {
            "vec3 light_vector = vec3(0.0);\n"
            "vec3 refl_value = vec3(0.0);\n";
 
-    // Convert interpolated quaternion to a GL fragment normal
-    out += "vec3 normal = normalize(vec3(\n";
-    out += "          2.f*(normquat.x*normquat.z + normquat.y*normquat.w),\n";
-    out += "          2.f*(normquat.y*normquat.z + normquat.x*normquat.w),\n";
-    out += "    1.f - 2.f*(normquat.x*normquat.x + normquat.y*normquat.y)));\n";
+    // Compute fragment normals
+    if (config.lighting.bump_mode == Pica::Regs::LightingBumpMode::NormalMap) {
+        // Bump mapping is enabled using a normal map, read perturbation vector from the selected texture
+        std::string bump_selector = std::to_string(config.lighting.bump_selector);
+        out += "vec3 surface_normal = 2.0 * texture(tex[" + bump_selector + "], texcoord[" + bump_selector + "]).rgb - 1.0;\n";
+
+        // Recompute Z-component of perturbation if 'renorm' is enabled, this provides a higher precision result
+        if (config.lighting.bump_renorm) {
+            std::string val = "(1.0 - (surface_normal.x*surface_normal.x + surface_normal.y*surface_normal.y))";
+            out += "surface_normal.z = sqrt(max(" + val + ", 0.0));\n";
+        }
+    } else if (config.lighting.bump_mode == Pica::Regs::LightingBumpMode::TangentMap) {
+        // Bump mapping is enabled using a tangent map
+        LOG_CRITICAL(HW_GPU, "unimplemented bump mapping mode (tangent mapping)");
+        UNIMPLEMENTED();
+    } else {
+        // No bump mapping - surface local normal is just a unit normal
+        out += "vec3 surface_normal = vec3(0.0, 0.0, 1.0);\n";
+    }
+
+    // Rotate the surface-local normal by the interpolated normal quaternion to convert it to eyespace
+    out += "vec3 normal = normalize(quaternion_rotate(normquat, surface_normal));\n";
 
     // Gets the index into the specified lookup table for specular lighting
     auto GetLutIndex = [config](unsigned light_num, Regs::LightingLutInput input, bool abs) {
@@ -516,6 +533,11 @@ layout (std140) uniform shader_data {
 uniform sampler2D tex[3];
 uniform sampler1D lut[6];
 
+// Rotate the vector v by the quaternion q
+vec3 quaternion_rotate(vec4 q, vec3 v) {
+    return v + 2.0 * cross(q.xyz, cross(q.xyz, v) + q.w * v);
+}
+
 void main() {
 vec4 primary_fragment_color = vec4(0.0);
 vec4 secondary_fragment_color = vec4(0.0);