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// Copyright (c) 2008 the OpenTK Team. See license.txt for legal bla

// custom vertex attribute

attribute vec3 AttributeTangent;

// world uniforms

uniform vec3 Light_Position;

uniform vec3 Camera_Position;

// MUST be written to for FS

varying vec3 VaryingLightVector;

varying vec3 VaryingEyeVector;

void main()

{

  gl_Position = ftransform();

  gl_TexCoord[0] = gl_TextureMatrix[0] * gl_MultiTexCoord0;

  vec3 nor = normalize( gl_NormalMatrix * gl_Normal );

  vec3 tan = normalize( gl_NormalMatrix * AttributeTangent );

  vec3 bi = cross(nor, tan);

  // need positions in tangent space

  vec3 vertex = vec3( gl_ModelViewMatrix * gl_Vertex );

  vec3 temp = Light_Position - vertex;

  VaryingLightVector.x = dot(temp, tan); // optimization, calculate dot products rather than building TBN matrix

  VaryingLightVector.y = dot(temp, bi);

  VaryingLightVector.z = dot(temp, nor);

  temp = Camera_Position - vertex;

  VaryingEyeVector.x = dot(temp, tan);

  VaryingEyeVector.y = dot(temp, bi);

  VaryingEyeVector.z = dot(temp, nor);

}