Add specular lighting

examples/dev_testing/resources/shaders/fragment_core.glsl

@@ -5,14 +5,18 @@ in mat4 vs_transform;
 in vec2 vs_texcoord;
 in vec3 vs_normal;
 in vec3 vs_to_light;
+in vec3 vs_to_camera;
 
 uniform bool texture_is_set;
 uniform sampler2D vs_texture;
 uniform vec3 light_color;
+uniform float shine_damper;
+uniform float reflectivity;
 
 out vec4 fs_color;
 
 void main() {
+    // Lighting
     vec3 unit_normal = normalize(vs_normal);
     vec3 unit_light_vector = normalize(vs_to_light);
 
@@ -20,9 +24,23 @@ void main() {
     float brightness = max(dot_prod, 0.f);
     vec3 diffuse = brightness * light_color;
 
+    // Specular lighting
+    // only do all this math is reflectivity is > 0
+    vec3 final_specular = vec3(0.f);
+    if (reflectivity > 0) {
+        vec3 unit_vector_to_camera = normalize(vs_to_camera);
+        vec3 light_direction = -unit_vector_to_camera;
+        vec3 reflected_light_dir = reflect(light_direction, unit_normal);
+        float specular_factor = dot(reflected_light_dir, unit_vector_to_camera);
+        specular_factor = max(specular_factor, 0.f);
+        float damped_specular = pow(specular_factor, shine_damper);
+        final_specular = damped_specular * reflectivity * light_color;
+    }
+
     if (texture_is_set) {
-        fs_color = vec4(diffuse, 1.f) * texture(vs_texture, vs_texcoord);
+        //fs_color = vec4(0.5 * unit_normal + vec3(0.5), 1.f); // Visualize normals
+        fs_color = vec4(diffuse, 1.f) * texture(vs_texture, vs_texcoord) + vec4(final_specular, 1.f);
     } else {
-        fs_color = vec4(diffuse, 1.f);
+        fs_color = vec4(diffuse, 1.f) + vec4(final_specular, 1.f);
     }
 }

examples/dev_testing/resources/shaders/vertex_core.glsl

@@ -9,6 +9,7 @@ out vec2 vs_texcoord;
 out mat4 vs_transform;
 out vec3 vs_normal;
 out vec3 vs_to_light;
+out vec3 vs_to_camera;
 
 uniform mat4 transform_matrix;
 uniform mat4 view_matrix;
@@ -26,11 +27,5 @@ void main() {
     
     vs_normal = (transform_matrix * vec4(vertex_normal, 0.f)).xyz;
     vs_to_light = light_position - world_pos.xyz;
-
-    /* vs_position = vec4(transform_matrix * vec4(vertex_position, 1.f)).xyz;
-    vs_transform = transform_matrix;
-    vs_color = vertex_color;
-    vs_texcoord = vertex_texcoord;
-
-    gl_Position = projection_matrix * view_matrix * transform_matrix * vec4(vertex_position, 1.0f); */
+    vs_to_camera = (inverse(view_matrix) * vec4(0.f, 0.f, 0.f, 1.f)).xyz - world_pos.xyz;
 }

examples/dev_testing/src/main.cpp

@@ -52,6 +52,8 @@ int main(int argc, char *argv[]) {
     game.add_event(light);
 
     simpleengine::gfx::Texture white_texture("resources/white_texture.png");
+    /* white_texture.shine_damper = 10;
+    white_texture.reflectivity = 1; */
     auto dragon = std::make_shared<simpleengine::objects_3d::ObjModel>(game.get_window(), core_shader, white_texture, "resources/dragon.obj");
     dragon->translate(0.f, -5.f, -25.f);
     game.add_event(dragon);

include/simpleengine/gfx/texture.h

@@ -29,6 +29,8 @@ namespace simpleengine::gfx {
         int height;
         int width;
         int channels;
+        float shine_damper = 1.f;
+        float reflectivity = 0.f;
 
         /**
          * @brief Construct a new Texture object from a path.

src/gfx/textured_model.cpp

@@ -19,6 +19,8 @@ namespace simpleengine::gfx {
     void TexturedModel::render(GLFWwindow* target) {
         shader.use();
         shader.set_uniform_matrix_4f("transform_matrix", transform_matrix, false);
+        shader.set_uniform_float("shine_damper", texture.shine_damper, false);
+        shader.set_uniform_float("reflectivity", texture.reflectivity, false);
 
         // When binding to the texture, tell the shader if the texture is set or not.
         shader.set_uniform_int("texture_is_set", (GLint) true, false);