// input
struct vtxin 
{
  float4 position: POSITION;
  float4 normal: NORMAL;
  float4 color: COLOR0;
  float4 texCoord: TEXCOORD0;
};


// vtx output
struct vtxout
{
	float4 position: POSITION;
	float4 texCoord: TEXCOORD0;    

	float4 color: COLOR0;  
	 // eye position
	float4 eyePos: TEXCOORD1;
	float4 normal: TEXCOORD2;
	float4 worldPos: TEXCOORD3;
	float4 oldWorldPos: TEXCOORD4;
};


// fragment input
struct fragin
{
	float4 color: COLOR0;  
	float4 texCoord: TEXCOORD0;    

	float4 winPos: WPOS;
	// eye position
	float4 eyePos: TEXCOORD1;
	float4 normal: TEXCOORD2;
	float4 worldPos: TEXCOORD3;
	float4 oldWorldPos: TEXCOORD4;
};


struct pixel
{
	float4 col: COLOR0;
	float3 norm: COLOR1;
	float3 offsVec: COLOR2;
};


#pragma position_invariant vtx

vtxout vtx(vtxin IN, 
		   uniform float4x4 viewMatrix,
		   uniform float4x4 modelMatrix,
		   uniform float4x4 oldModelMatrix)
{
	vtxout OUT;

	OUT.color = IN.color;
	OUT.texCoord = IN.texCoord;

	// transform the vertex position into eye space
	OUT.eyePos = mul(glstate.matrix.modelview[0], IN.position);
	// transform the vertex position into post projection space
	OUT.position = mul(glstate.matrix.mvp, IN.position);
	// transform the old vertex position into world space
	OUT.worldPos = mul(modelMatrix, IN.position);
	// transform the old vertex position into world space
	OUT.oldWorldPos = mul(oldModelMatrix, IN.position);
	// the normal has to be correctly transformed with the inverse transpose
	OUT.normal = mul(glstate.matrix.invtrans.modelview[0], IN.normal);
	//OUT.normal = IN.normal;

	return OUT;
}


pixel fragtex(fragin IN, 
			  uniform sampler2D tex: TEXUNIT0,
			  uniform float4x4 viewMatrix
			  )
{
	float4 texColor = tex2D(tex, IN.texCoord.xy);

	// account for alpha blending
	if (texColor.w < .5f) discard;

	pixel pix;

	// save color in first render target
	// hack: use combination of emmisive + diffuse (emmisive used as constant ambient term)
	pix.col = (glstate.material.emission + glstate.material.diffuse) * texColor; 
	// save world space normal in rt => transform back into world space by
	// multiplying with inverse view. since transforming normal with T means to 
	// multiply with the inverse transpose of T, we multiple with 
	// Transp(Inv(Inv(view))) = Transp(view)
	pix.norm = normalize(mul(transpose(viewMatrix), IN.normal).xyz);
	//pix.norm = IN.normal.xyz;
	// compute eye linear depth
	pix.col.w = length(IN.eyePos.xyz);

	// the scene entity id
	//pix.id = glstate.fog.color.xyz;
	// the offset to the world pos from old frame
	//pix.offsVec = float3(0,0,0);
	pix.offsVec = IN.oldWorldPos.xyz - IN.worldPos.xyz;

	return pix;
}


pixel frag(fragin IN, uniform float4x4 viewMatrix)
{
	pixel pix;
	// hack: use comination of emmisive + diffuse (emmisive used as constant ambient term)
	pix.col = glstate.material.diffuse + glstate.material.emission;
	// save world space normal in rt => transform back into world space by
	// multiplying with inverse view. since transforming normal with T means to 
	// multiply with the inverse transpose of T, we multiple with Transp(Inv(Inv(view))) = Transp(view)
	pix.norm = normalize(mul(transpose(viewMatrix), IN.normal).xyz);
	//pix.norm = IN.normal.xyz;
	// eye space depth
	pix.col.w = length(IN.eyePos.xyz);
	// the scene entity id
	//pix.id = glstate.fog.color.xyz;
	// the offset to the world pos from old frame
	pix.offsVec = IN.oldWorldPos.xyz - IN.worldPos.xyz;
	//pix.offsVec = float3(0,0,0);

	return pix;
}