/*******************************************************************************
 *
 * Simple GLSL FX file
 *
 *******************************************************************************/

#pragma language GLSL

// un-tweakables



// structures and shaders /////////////////////

varying vec3 eyeNormal;
varying vec4 eyePos;
varying vec3 eyeView;
varying vec3 tangent;
varying vec3 binormal;

void mainVS()
{ 

	//	Must write gl_Position for rasterization to be defined....
	//
	gl_Position = ftransform(); 

	//	Transform to shading space (we are going to shade in eyespace)
	//
	//
	eyeNormal = gl_NormalMatrix * gl_Normal;

	eyeView = -vec3(gl_ModelViewMatrix * gl_Vertex);

    tangent = normalize(gl_NormalMatrix * gl_MultiTexCoord1.stp);
    binormal = gl_NormalMatrix * gl_MultiTexCoord2.stp;
}

uniform vec3 lightDir = vec3( 0.57735, 0.57735, 0.57735);
uniform vec3 lightColor = vec3( 1.0, 1.0, 1.0);

uniform float xRoughness = 0.5;
uniform float yRoughness = 0.15; 

void mainPS()
{
  
  //
  //	Since the EyeNormal is getting interpolated, we
  //	have to first restore it by normalizing it.
  //
  vec3 norm = normalize( eyeNormal );
  vec3 view = normalize(eyeView);
  vec3 hvec = normalize(view+lightDir);
  vec3 tan = normalize(tangent) / xRoughness;
  vec3 binorm = normalize(cross(norm,tan)) / yRoughness;

  float cos_theta_r = clamp( dot( norm, view), 0.0, 1.0); 
  float cos_theta_i = clamp( dot( norm, lightDir), 0.0, 1.0);
  float xDotH = dot( tan, hvec);
  float yDotH = dot( binorm, hvec);
  float rho = exp( -2.0*(xDotH*xDotH + yDotH*yDotH) / (1.0 + dot(hvec, norm)));
  rho = rho * inversesqrt( cos_theta_i * cos_theta_r); 

  float illum = ( cos_theta_i > 0.0) ? cos_theta_i * rho : 0.0;
  illum /= 4.0*xRoughness*yRoughness;
	
  gl_FragColor = vec4( illum*lightColor, 1.0);

}


//////// techniques ////////////////////////////

technique aniso
{
	pass p0
	{
		VertexShader = compile vs_2_0 mainVS();
		
		ZEnable = true;
		ZWriteEnable = true;
        ZFunc = LEqual;
		CullMode = Back;

		PixelShader = compile ps_2_0 mainPS();
	}
}