normal map hlsl

Texture2D ShaderTexture : register(t0);
SamplerState Sampler : register(s0);
cbuffer PerObject: register(b0)
{
	float4x4 ViewMatrix;
	float2 TextureSize;
	float Bias;
	float InvertR;
	float InvertG;
	float Unused1;
	float Unused2;
	float Unused3;
};
struct VertexShaderInput
{
	float4 Position : SV_Position;
	float2 TextureUV : TEXCOORD0;
};
struct VertexShaderOutput
{
	float4 Position : SV_Position;
	float2 TextureUV : TEXCOORD0;
};
VertexShaderOutput VSMain(VertexShaderInput input)
{
	VertexShaderOutput output = (VertexShaderOutput)0;
	output.Position = mul(input.Position, ViewMatrix);
	output.TextureUV = input.TextureUV;
	return output;
}
float4 PSMain(VertexShaderOutput input) : SV_Target
{
	float2 step = float2(1.0f, 1.0f) / TextureSize;
	float2 tlv = float2(input.TextureUV.x - step.x, input.TextureUV.y + step.y);
	float2 lv = float2(input.TextureUV.x - step.x, input.TextureUV.y);
	float2 blv = float2(input.TextureUV.x - step.x, input.TextureUV.y - step.y);
	float2 tv = float2(input.TextureUV.x, input.TextureUV.y + step.y);
	float2 bv = float2(input.TextureUV.x, input.TextureUV.y - step.y);
	float2 trv = float2(input.TextureUV.x + step.x, input.TextureUV.y + step.y);
	float2 rv = float2(input.TextureUV.x + step.x, input.TextureUV.y);
	float2 brv = float2(input.TextureUV.x + step.x, input.TextureUV.y - step.y);
	
	tlv = float2(tlv.x >= 0.0 ? tlv.x : (1.0 + tlv.x), tlv.y >= 0.0 ? tlv.y : (1.0 + tlv.y));
	tlv = float2(tlv.x < 1.0 ? tlv.x : (tlv.x - 1.0), tlv.y < 1.0 ? tlv.y : (tlv.y - 1.0));
	lv = float2(lv.x >= 0.0 ? lv.x : (1.0 + lv.x), lv.y >= 0.0 ? lv.y : (1.0 + lv.y));
	lv = float2(lv.x < 1.0 ? lv.x : (lv.x - 1.0), lv.y < 1.0 ? lv.y : (lv.y - 1.0));
	blv = float2(blv.x >= 0.0 ? blv.x : (1.0 + blv.x), blv.y >= 0.0 ? blv.y : (1.0 + blv.y));
	blv = float2(blv.x < 1.0 ? blv.x : (blv.x - 1.0), blv.y < 1.0 ? blv.y : (blv.y - 1.0));
	tv = float2(tv.x >= 0.0 ? tv.x : (1.0 + tv.x), tv.y >= 0.0 ? tv.y : (1.0 + tv.y));
	tv = float2(tv.x < 1.0 ? tv.x : (tv.x - 1.0), tv.y < 1.0 ? tv.y : (tv.y - 1.0));
	bv = float2(bv.x >= 0.0 ? bv.x : (1.0 + bv.x), bv.y >= 0.0 ? bv.y : (1.0 + bv.y));
	bv = float2(bv.x < 1.0 ? bv.x : (bv.x - 1.0), bv.y < 1.0 ? bv.y : (bv.y - 1.0));
	trv = float2(trv.x >= 0.0 ? trv.x : (1.0 + trv.x), trv.y >= 0.0 ? trv.y : (1.0 + trv.y));
	trv = float2(trv.x < 1.0 ? trv.x : (trv.x - 1.0), trv.y < 1.0 ? trv.y : (trv.y - 1.0));
	rv = float2(rv.x >= 0.0 ? rv.x : (1.0 + rv.x), rv.y >= 0.0 ? rv.y : (1.0 + rv.y));
	rv = float2(rv.x < 1.0 ? rv.x : (rv.x - 1.0), rv.y < 1.0 ? rv.y : (rv.y - 1.0));
	brv = float2(brv.x >= 0.0 ? brv.x : (1.0 + brv.x), brv.y >= 0.0 ? brv.y : (1.0 + brv.y));
	brv = float2(brv.x < 1.0 ? brv.x : (brv.x - 1.0), brv.y < 1.0 ? brv.y : (brv.y - 1.0));

	float tl = abs(ShaderTexture.Sample(Sampler, tlv).r);
	float l = abs(ShaderTexture.Sample(Sampler, lv).r);
	float bl = abs(ShaderTexture.Sample(Sampler, blv).r);
	float t = abs(ShaderTexture.Sample(Sampler, tv).r);
	float b = abs(ShaderTexture.Sample(Sampler, bv).r);
	float tr = abs(ShaderTexture.Sample(Sampler, trv).r);
	float r = abs(ShaderTexture.Sample(Sampler, rv).r);
	float br = abs(ShaderTexture.Sample(Sampler, brv).r);

	//Sobel
	float dx = tl + l * 2.0 + bl - tr - r * 2.0 - br;
	float dy = tl + t * 2.0 + tr - bl - b * 2.0 - br;

	// Scharr
	//float dx = tl * 3.0 + l * 10.0 + bl * 3.0 - tr * 3.0 - r * 10.0 - br * 3.0;
	//float dy = tl * 3.0 + t * 10.0 + tr * 3.0 - bl * 3.0 - b * 10.0 - br * 3.0;

	float4 normal = float4(normalize(float3(dx * InvertR, dy * InvertG, 1.0f - (Bias / 100.0f))), 1.0f);
	return float4(normal.xy * 0.5f + 0.5f, normal.zw);
}