uniform vec3 D_LightDir;
uniform vec3 P_LightPos;
uniform vec3 cameraPos;

// vertex position: uniform vec4 gl_Vertex;
// vertex normal: uniform vec3 gl_Normal;
// vertex color: uniform vec4 gl_Color;

void main() {
	vec4 vertex_light;

    // this shader is executed for each vertex
    // compute light at this vertex and update the front color below
    gl_FrontColor = gl_Color;
    vertex_light = vec4(dot(gl_Normal, P_LightPos));

    // directional light: gl_FrontColor *= vec4(dot(gl_Normal, D_LightDir));
    /* gl_FrontColor = gl_Frontcolor * vec4(dot(gl_Normal, P_LightPos))
       the front color will be the color (blue) times the vertex light (white),
       the following division will make the object (blue) and the light (white) have a
       smoother transition. The higher the divider, the smoother the transition */
    gl_FrontColor *= vertex_light / vec4(35, 35, 35, 35);
    gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;

}