Document code, and clean up

src/data/shaders.h

@@ -62,7 +62,12 @@ const char * fs =
 	"	vec3 lightPos = vec3(0,0,-15);"
 	"	vec3 lightDir = normalize(lightPos - FragPos);"
 
-	"	float diffuse = max(dot(Normal, lightDir), 0.0);"
+/*
+	We use the absoulute value, insted of the traditional "max(...,0.0);"
+	so we can ignore the orientation of the triangles in openGL. 
+*/
+	"	float diffuse = abs(dot(Normal, lightDir)); "
+
 	"	float ambient = 0.5;"
 	"	FragColor = (ambient + diffuse)*color;"
 	"}";