basic normal map shader

Scripting Issues
5

That was exactly the direction I meant, thanks :smiley:. Got it working now!

//Cg 
//Cg profile arbvp1 arbfp1 

void vshader(
		in float2 vtx_texcoord0 : TEXCOORD0, 
		in float4 vtx_position : POSITION,
		in float4 vtx_normal : NORMAL,
		in float4 vtx_tangent1,
		in float4 vtx_binormal1,
		uniform float4x4 mat_modelproj,
		uniform float4x4 trans_world_to_model,

		in uniform float3 k_dlightvec, 

		out float2 l_texcoord0 : TEXCOORD0, 
		out float4 l_position : POSITION,
		out float3 l_normal,
		out float3 l_tangent,
		out float3 l_binormal,
		out float3 l_dlightvec
) { 
	l_position=mul(mat_modelproj,vtx_position); 
	l_texcoord0=vtx_texcoord0;

	l_normal = vtx_normal.xyz;
	l_tangent = vtx_tangent1.xyz;
	l_binormal = -vtx_binormal1.xyz;

	l_dlightvec = normalize(mul((float3x3)trans_world_to_model, -k_dlightvec));
}

void fshader(
		uniform sampler2D tex_0 : TEXUNIT0,
		uniform sampler2D tex_1 : TEXUNIT1,

		in float2 l_texcoord0 : TEXCOORD0, 
		in float4 l_position : POSITION,
		in float3 l_normal,
		in float3 l_tangent,
		in float3 l_binormal,
		in float3 l_dlightvec,

		in uniform float4 k_dlightcolor, 
		in uniform float4 k_alightcolor,

		out float4 o_color : COLOR
) {
	// Getting the correct normals
	float3 TN = tex2D( tex_1, l_texcoord0 ) * 2.0 - 1.0 ; //Texture normal
	float3 CN = l_normal; //Combined normal
	CN *= TN.z;
	CN += l_tangent * TN.x;
	CN += l_binormal * TN.y;
	CN = normalize(CN);

	// Getting the correct light for this fragment
	float4 lightcolor = k_alightcolor;
	lightcolor += k_dlightcolor*saturate(dot(CN,l_dlightvec));
	lightcolor = saturate(lightcolor);

	// Final fragment color
	o_color = tex2D( tex_0, l_texcoord0 );
	o_color *= lightcolor;
}

Even though the shader is working I still have some questions:

  1. Am I correct to think that the tangent is a vector in the direction of where the x-direction of the texture is going on the model? (So the direction (u,v)->(u+.0001,v) mapped on the model) and the binormal the y-direction ((u,v)->(u,v+.0001)
  2. Why does the binormal have to be multiplied by -1 (i think because the y direction on a uv map is opposite to the y-direction in model space)
  3. why does the light vector have to be multiplied by -1

I am already very pleased with the results but it is much appreciated if someone could confirm my first two ideas!