//http://www.smart-page.net/blog/2009/08/27/smart-normal-map-goes-silverlight/
//Generates a normalmap using condensed or sobel-edge.
float width 		: register(C0);
float soft_sobel        : register(C1);
float amount 		: register(C2);
float invert_red 	: register(C3);
float invert_green 	: register(C4);

sampler2D 	Input 	: register(S0); 

float4 main(float2 uv:TEXCOORD) : COLOR {

	float dx;
	float dy;
	
	float texel = 1.0f / width;

	if (soft_sobel!=0.0) {
			//condensed
            dx  = abs(tex2D (Input, uv + texel *float2(1,  0)).x).r - abs(tex2D (Input, uv + texel *float2(-1,  0)).x).r;
            dy  = abs(tex2D (Input, uv + texel *float2(0, -1)).x).r - abs(tex2D (Input, uv + texel *float2( 0,  1)).x).r;	
 	} else {
    		//sobel
		    dx  = abs(tex2D (Input, uv + texel *float2(-1, -1)).x).r /-1.0f;      
		    dx += abs(tex2D (Input, uv + texel *float2(-1,  0)).x).r /-2.0f;  
		    dx += abs(tex2D (Input, uv + texel *float2(-1,  1)).x).r /-1.0f;  
		    dx += abs(tex2D (Input, uv + texel *float2( 1, -1)).x).r / 1.0f;
		    dx += abs(tex2D (Input, uv + texel *float2( 1,  0)).x).r / 2.0f; 
		    dx += abs(tex2D (Input, uv + texel *float2( 1,  1)).x).r / 1.0f;  
		    
		    dy  = abs(tex2D (Input, uv + texel *float2(-1,  1)).x).r /-1.0f;      
		    dy += abs(tex2D (Input, uv + texel *float2( 0,  1)).x).r /-2.0f;  
		    dy += abs(tex2D (Input, uv + texel *float2( 1,  1)).x).r /-1.0f;  
		    dy += abs(tex2D (Input, uv + texel *float2(-1, -1)).x).r / 1.0f;
		    dy += abs(tex2D (Input, uv + texel *float2( 0, -1)).x).r / 2.0f; 
		    dy += abs(tex2D (Input, uv + texel *float2( 1, -1)).x).r / 1.0f; 
	}    
    
    float3 normal = float3(dx * (invert_red) * (amount / (1.0 + float(soft_sobel))), - (dy*invert_green) * (amount / (1.0 + float(soft_sobel))), 1.0);
    normal = ((normal+1.0) / 2.0 );

    float4 N = float4(normal.r, normal.g, normal.b, 1.0f);

    return N;
}