cooktorrance.cg

/* 
	VERTEX SHADER FOR SIMPLE LIGHT MODELS

	created by Daniel Jungblut, IWR Heidelberg, February 2008
	refined by Bastian Rieck, IWR Heidelberg, May 2010


	Simplified Blinn-Phong shading model for a single light source. Hit SPACE in
	order to move the light source. All vector calculations should be made in
	world coordinates.

	The following functions might be helpful:
		
		A = normalize(B)	[normalizing a vector]
		
		float s = dot(A, B)	[dot product, scalar product]
		float m = max(a, b)	[maximum of two vectors]
		float p = pow(a, b)	[power function]

*/  

void per_vertex_lighting(

		float4 position : POSITION,	    // input coordinates (object space)
		out float4 out_position : POSITION, // output coordinates ("screen" space)
		uniform float3 translation, 
		float3 normal : NORMAL, 	    // surface normal (object space)
		out float4 out_color : COLOR,       // output colour of vertex
		uniform float4x4 modelview_proj,    // concatenation of modelview and projection matrix

		uniform float3 ambient_light,	   // ambient light colours des ambienten Lichts
		uniform float3 light_color,        // light colour 
		uniform float4 light_position,     // light position (world coordinates)
		uniform float4 camera_position,    // viewer position (world coordinates)
		uniform float3 Ke,                 // material properties: emitting part
		uniform float3 Ka,		   // material properties: ambient part
		uniform float3 Kd,		   // material properties: diffuse part
		uniform float3 Ks,		   // material properties: specular part
		uniform float exponent             // material properties: exponent for specular term
		) 
{	

	out_position = mul(modelview_proj, position);
	
	float3 P = position.xyz + translation;	// vertex position in world coordinates 
	float3 N = normal;			// normal in world coordinates
	float F = 1.0f;
	float D = 1.0f;
	float3 emissive = Ke;

	float3 ambient = Ka * ambient_light;

	float3 L = normalize(light_position.xyz - P);
	float diffuse_light = max(dot(N, L), 0);
	float3 diffuse = Kd * light_color * diffuse_light;

	float3 V = normalize(camera_position.xyz - P);
	float3 H = normalize(L + V);
	float3 R = reflect(L, N);
	
	float VdotN = max(dot(V, N), 0.0);
	float LdotN = max(dot(L, N), 0.0);
	float NdotH = max(dot(N, H), 0.0);
	float VdotH = max(dot(V, H), 0.000001);
	float LdotH = max(dot(L, H), 0.000001);
	float G1 = (2.0 * NdotH * VdotN) / VdotH;
	float G2 = (2.0 * NdotH * LdotN) / LdotH;
	float G = min(1.0, min(G1, G2));

	float3 specular =  G * F * D / max(3.14159265 * VdotN, 0.000001);

	out_color.xyz = emissive + ambient + diffuse + specular;
	out_color.w = 1.0;
}