add blinn-phong lighting demo

1 files changed, 24 insertions, 2 deletions

diff --git a/demo.fs b/demo.fs
index a9a0275..65700b7 100644
--- a/demo.fs
+++ b/demo.fs
@@ -1,15 +1,37 @@
 #version 330 core
 
+in vec3 normal;
 in vec2 texture_coordinate;
+in vec3 fragment_position;
+
+uniform vec3 ambient_color;
 
 uniform vec3 light_color;
+uniform vec3 light_position;
 
 uniform sampler2D box_texture;
 uniform sampler2D happy_texture;
 
+uniform mat4 model;
+uniform mat4 view;
+
 out vec4 fragment_color;
 
 void main()
 {
-  fragment_color = texture(box_texture, texture_coordinate) * vec4(light_color.xyz, 1.0);
-}
+  /* diffuse light */
+  vec3 norm = normalize(normal);
+  vec3 light_pos = vec3(view * vec4(light_position.xyz, 1.0));
+  vec3 light_direction = normalize(light_pos - fragment_position);
+  float diffuse = max( dot(norm, light_direction), 0 );
+  vec3 diffuse_light = light_color * diffuse;
+
+  /* specular reflection */
+  vec3 view_direction = normalize(-fragment_position);
+  vec3 reflection_direction = reflect(-light_direction, norm);
+  float specular = pow(max(dot(view_direction, reflection_direction), 0), 32);
+  vec3 specular_light = 1.0 * specular * light_color;
+
+  vec4 total_light = vec4((ambient_color + diffuse_light + specular_light).xyz, 1.0);
+  fragment_color = total_light * texture(box_texture, texture_coordinate);
+}