/******************************************************************************
HLSL NormalMap Maker
by Ben Cloward
bsmji@hotmail.com
http://www.monitorstudios.com/bcloward/

This shader is based on several shaders written by Kevin Bjorke of Nvidia and 
included with the Cg plugin for 3DS Max.

The purpose of this shader is to generate a normal map from your high res model 
that you can then apply to your low res model using another shader.  This shader
is different from all the other shaders I've written because it's meant to be
applied to a high res model as part of the process of creating your art
- instead of being applied to the low res model at the end of the process. It's
just a clever way of using the graphics hardware to create an instant normal map
instead of having to wait for the software renderer to do it.  Just follow the
steps below to make it work.

1. Create a highly detailed model.  It could be a brick wall, a metal panel with
rivets, etc.  (This shader works best on objects that can are mainly flat or that
can be tiled.  It doesn't work well for characters or other objects that need to
be unwrapped to texture.)

2. Apply this shader to your model and take a screen shot from an orthographic
viewport (top, front, etc.)

3. Paste the screen shot into an image in Photoshop or other image software.
Scale and crop the image so just the object is showing and the texture is 256x256
or 512x512, etc.

4. Now you've got a normal map.  Save it and apply it to your low res model using
one of my other shaders that supports normal maps.

It requires hardware support for DirectX 9.

This shader is intended to be used by the DirectX 9 shader of 3DS Max
but it could also be used in other applications that support the FX format.


******************************************************************************/

/*** automatically-tracked "tweakables" ********/

float4x4 wvp : WORLDVIEWPROJ < string UIWidget = "None"; >;
float4x4 WORLDVIEWIT : WORLDVIEWIT < string UIWidget = "None"; >;

/********** CG SHADER FUNCTIONS *********************/

// input from application
	struct a2v {
	float4 position : POSITION;
	float3 normal   : NORMAL;
};

// output to fragment program
struct v2f {
        float4 position    	: POSITION;
        float3 normal		: TEXCOORD0;
};

/***** VERTEX SHADER ******************/

v2f v(a2v In,
		uniform float4x4 worldViewProj, // object to clip space
        uniform float4x4 WORLDVIEWIT
        )
{
  v2f Out;
  float4 N = mul(In.normal, -WORLDVIEWIT);  //normal to camera space
  Out.position = mul(In.position, worldViewProj); //vertex to clip space
  Out.normal = N;
  return Out;
}

/***** FRAGMENT PROGRAM ***************/

float4 f(v2f In) : COLOR
{     
	float4 color = float4(In.normal,1);
	color.x = -color.x;
	color.y = -color.y;
	return color * 0.5 + 0.5;
}

/********** TECHNIQUES ******************************/

technique Complete
{ 
    pass envPass 
    {		
	VertexShader = compile vs_1_1 v(wvp,WORLDVIEWIT);
	ZEnable = true;
	ZWriteEnable = true;
	CullMode = CW;
	PixelShader = compile ps_2_0 f();
    }
}