/*
*   Vertex shader for "angle-of-incidence" based shading: computes the usual
*       lighting / normal varyings, and also computes the normal in device
*       coordinates (see notes below; technically in clip space here).
*
*   Alexandri Zavodny, Fall 2010 
*       for CSE 40166/60166 Computer Graphics, University of Notre Dame
*/

varying vec4 theColor;
varying vec3 theNormal;
varying vec4 normalInDeviceCoords;
varying vec3 dirToLight;

void main()
{
    theColor = gl_Color;
    vec4 transformedVertex = gl_ModelViewMatrix * gl_Vertex;
    dirToLight = normalize( vec3(gl_LightSource[0].position - transformedVertex) );

    theNormal = normalize(gl_NormalMatrix * gl_Normal);

    //ok, so TECHNICALLY the normal is in clip space here, but it'll be in
    //normalized device coordinates by the time it reaches the fragment processor.
    normalInDeviceCoords = normalize(gl_ProjectionMatrix * vec4(theNormal, 0.0));

    gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;
}