1 files changed, 20 insertions, 1 deletions
diff --git a/dev/a5-artrender/shaders/phong.frag b/dev/a5-artrender/shaders/phong.frag
index 2f7c013..5c51159 100644
--- a/dev/a5-artrender/shaders/phong.frag
+++ b/dev/a5-artrender/shaders/phong.frag
@@ -13,5 +13,24 @@ uniform float s;
 
 
 void main() {
-    color = vec4(0,0,0,1);
+    // transoform the vertex position into "eye space"
+    vec3 v = position_in_eye_space;
+
+    // unit vector from the vertex to the light
+    vec3 l = normalize(light_in_eye_space - v);
+    
+    // unit vector from the vertex to the eye point, which is at 0,0,0 in "eye space"
+    vec3 e = normalize(vec3(0,0,0) - v);
+
+    // normal transformed into "eye space"
+    vec3 n = normalize(normalize(normal_in_eye_space));
+    // halfway vector
+    vec3 h = normalize(e+l);
+
+    // calculate color using the light intensity equation
+    vec4 ambient = ka * Ia;
+    vec4 diffuse = kd * Id * max(dot(n, l), 0);
+    vec4 specular = ks * Is * pow(max(dot(h, n), 0), s);
+    
+    color = ambient + diffuse + specular;
 }