Added vertex attributes.

assets/shaders/singleDiffuseLight/singleDiffuseLight_vert.glsl

@@ -4,6 +4,13 @@ uniform mat4 u_projTrans;
 // Vertex position in world coordinates.
 attribute vec4 a_position;
 
+// Vertex color.
+attribute vec4 a_color;
+
+// Vertex color to pass to the fragment shader.
+varying vec4 v_color;
+
 void main(){
+	v_color = a_color;
 	gl_Position = u_projTrans * a_position;
 }