Changeset 9dd2eb7 in opengl-game for texture.frag

Timestamp:

Apr 28, 2018, 2:29:20 AM (6 years ago)

Author:

Dmitry Portnoy <dmp1488@…>

Branches:

feature/imgui-sdl, master, points-test

Children:

9f4986b

Parents:

d9f99b2

Message:

Implement Phong shading in the color and texture shaders

File:

• texture.frag (modified) (1 diff)

texture.frag

@@ -4 +4 @@
 
 in vec2 texture_coordinates;
+in vec3 position_eye, normal_eye, light_position_eye;
 
 out vec4 frag_color;
 
+// fixed point light properties
+vec3 Ls = vec3(1.0, 1.0, 1.0); // white specular colour
+vec3 Ld = vec3(0.7, 0.7, 0.7); // dull white diffuse light colour
+vec3 La = vec3(0.2, 0.2, 0.2); // grey ambient colour
+
+// surface reflectance
+vec3 Ks = vec3(1.0, 1.0, 1.0); // fully reflect specular light
+vec3 Kd = vec3(1.0, 0.5, 0.0); // orange diffuse surface reflectance
+vec3 Ka = vec3(0.2, 0.2, 0.2); // fully reflect ambient light
+float specular_exponent = 100.0; // specular 'power'
+
 void main() {
   vec4 texel = texture(basic_texture, texture_coordinates);
-  frag_color = texel;
+
+  // ambient intensity
+  vec3 Ia = La * Ka;
+
+  vec3 direction_to_light_eye = normalize(light_position_eye - position_eye);
+  float dot_prod = max(dot(direction_to_light_eye, normal_eye), 0.0);
+
+  // diffuse intensity
+  vec3 Id = Ls * vec3(texel) * dot_prod;
+
+  vec3 reflection_eye = reflect(-direction_to_light_eye, normal_eye);
+  vec3 surface_to_viewer_eye = normalize(-position_eye);
+  float dot_prod_specular = max(dot(reflection_eye, surface_to_viewer_eye), 0.0);
+  float specular_factor = pow(dot_prod_specular, specular_exponent);
+
+  // specular intensity
+  vec3 Is = Ls * Ks * specular_factor;
+
+  frag_color = vec4(Is + Id + Ia, 1.0);
 }