uniform float4x4 ViewProj;
uniform texture2d image;
uniform texture2d displacementMap;
uniform float2 texelScale;
uniform float2 displacementScale;

sampler_state textureSampler {
	Filter    = Linear;
	AddressU  = Wrap;
	AddressV  = Wrap;
};
sampler_state dispTextureSampler {
	Filter    = Linear;
	AddressU  = Clamp;
	AddressV  = Clamp;
};

struct VertDataIn {
	float4 pos : POSITION;
	float2 uv  : TEXCOORD0;
};

struct VertDataOut {
	float4 pos : POSITION;
	float2 uv  : TEXCOORD0;
};

VertDataOut VSDefault(VertDataIn v_in)
{
	VertDataOut vert_out;
	vert_out.pos = mul(float4(v_in.pos.xyz, 1.0), ViewProj);
	vert_out.uv  = v_in.uv;
	return vert_out;
}

float4 PSDisplace(VertDataOut v_in) : TARGET
{
	float2 disp = displacementMap.Sample(dispTextureSampler, v_in.uv).rg - float2(.5, .5);

	// Method 1: Only Math
	disp = (floor(abs(disp * 255.0)) / 255.0) * sign(disp);

	float2 uv = v_in.uv + (disp * texelScale * displacementScale);

	return image.Sample(textureSampler, uv);
}

technique Draw
{
	pass
	{
		vertex_shader = VSDefault(v_in);
		pixel_shader  = PSDisplace(v_in);
	}
}