// license:BSD-3-Clause
// copyright-holders:Ryan Holtz
//-----------------------------------------------------------------------------
// YIQ Decode Effect
//-----------------------------------------------------------------------------

texture Composite;

sampler CompositeSampler = sampler_state
{
	Texture   = <Composite>;
	MipFilter = POINT;
	MinFilter = POINT;
	MagFilter = POINT;
	AddressU = CLAMP;
	AddressV = CLAMP;
	AddressW = CLAMP;
};

texture Diffuse;

sampler DiffuseSampler = sampler_state
{
	Texture   = <Diffuse>;
	MipFilter = LINEAR;
	MinFilter = LINEAR;
	MagFilter = LINEAR;
	AddressU = CLAMP;
	AddressV = CLAMP;
	AddressW = CLAMP;
};

//-----------------------------------------------------------------------------
// Vertex Definitions
//-----------------------------------------------------------------------------

struct VS_OUTPUT
{
	float4 Position : POSITION;
	float4 Coord0 : TEXCOORD0;
};

struct VS_INPUT
{
	float4 Position : POSITION;
	float4 Color : COLOR0;
	float2 TexCoord : TEXCOORD0;
	float2 Unused : TEXCOORD1;
};

struct PS_INPUT
{
	float4 Coord0 : TEXCOORD0;
};

//-----------------------------------------------------------------------------
// YIQ Decode Vertex Shader
//-----------------------------------------------------------------------------

uniform float2 ScreenDims;
uniform float2 SourceDims;
uniform float2 SourceRect;

VS_OUTPUT vs_main(VS_INPUT Input)
{
	VS_OUTPUT Output = (VS_OUTPUT)0;
	
	Output.Position = float4(Input.Position.xyz, 1.0f);
	Output.Position.xy /= ScreenDims;
	Output.Position.y = 1.0f - Output.Position.y;
	Output.Position.xy -= 0.5f;
	Output.Position *= float4(2.0f, 2.0f, 1.0f, 1.0f);
	Output.Coord0.xy = Input.TexCoord;
	Output.Coord0.zw = float2(1.0f / SourceDims.x, 0.0f);

	return Output;
}

//-----------------------------------------------------------------------------
// YIQ Decode Pixel Shader
//-----------------------------------------------------------------------------

uniform float AValue = 0.0f;
uniform float BValue = 0.0f;
uniform float CCValue = 3.04183f;
uniform float PValue = 1.0f;
uniform float OValue = 0.0f;
uniform float ScanTime = 52.6f;

uniform float NotchHalfWidth = 1.0f;
uniform float YFreqResponse = 6.0f;
uniform float IFreqResponse = 1.2f;
uniform float QFreqResponse = 0.6f;

uniform float PI = 3.141592653589;
uniform float PI2 = 6.283185307178;

float4 ps_main(PS_INPUT Input) : COLOR
{
	float4 BaseTexel = tex2D(DiffuseSampler, Input.Coord0.xy + 0.5f / SourceDims);

	// YIQ convolution: N coefficients each
	float4 YAccum = 0.0f;
	float4 IAccum = 0.0f;
	float4 QAccum = 0.0f;
	float MaxC = 2.1183f;
	float MinC = -1.1183f;
	float CRange = MaxC - MinC;
	float FrameWidthx4 = SourceDims.x * 4.0f * SourceRect.x;
	float Fc_y1 = (CCValue - NotchHalfWidth) * ScanTime / FrameWidthx4;
	float Fc_y2 = (CCValue + NotchHalfWidth) * ScanTime / FrameWidthx4;
	float Fc_y3 = YFreqResponse * ScanTime / FrameWidthx4;
	float Fc_i = IFreqResponse * ScanTime / FrameWidthx4;
	float Fc_q = QFreqResponse * ScanTime / FrameWidthx4;
	float Fc_i_2 = Fc_i * 2.0f;
	float Fc_q_2 = Fc_q * 2.0f;
	float Fc_y1_2 = Fc_y1 * 2.0f;
	float Fc_y2_2 = Fc_y2 * 2.0f;
	float Fc_y3_2 = Fc_y3 * 2.0f;
	float Fc_i_pi2 = Fc_i * PI2;
	float Fc_q_pi2 = Fc_q * PI2;
	float Fc_y1_pi2 = Fc_y1 * PI2;
	float Fc_y2_pi2 = Fc_y2 * PI2;
	float Fc_y3_pi2 = Fc_y3 * PI2;
	float PI2Length = PI2 / 82.0f;
	float4 NOffset = float4(0.0f, 1.0f, 2.0f, 3.0f);
	float W = PI2 * CCValue * ScanTime;
	float4 CoordY = Input.Coord0.y;
	float4 VPosition = (CoordY * SourceRect.y) * (SourceDims.x / SourceRect.x);
	for(float n = -41.0f; n < 42.0f; n += 4.0f)
	{
		float4 n4 = n + NOffset;
		float4 CoordX = Input.Coord0.x + Input.Coord0.z * n4 * 0.25f;
		float2 TexCoord = float2(CoordX.r, CoordY.r);
		float4 C = tex2D(CompositeSampler, TexCoord + float2(0.5f, 0.0f) / SourceDims) * CRange + MinC;
		float4 T = (CoordX / SourceRect.x) + VPosition + BValue;
		float4 WT = W * T + OValue;
		float4 SincKernel = 0.54f + 0.46f * cos(PI2Length * n4);

		float4 SincYIn1 = Fc_y1_pi2 * n4;
		float4 SincYIn2 = Fc_y2_pi2 * n4;
		float4 SincYIn3 = Fc_y3_pi2 * n4;
		float4 SincIIn = Fc_i_pi2 * n4;
		float4 SincQIn = Fc_q_pi2 * n4;

		float4 SincY1 = ((SincYIn1 != 0.0f) ? (sin(SincYIn1) / SincYIn1) : 1.0f);
		float4 SincY2 = ((SincYIn2 != 0.0f) ? (sin(SincYIn2) / SincYIn2) : 1.0f);
		float4 SincY3 = ((SincYIn3 != 0.0f) ? (sin(SincYIn3) / SincYIn3) : 1.0f);

		float4 IdealY = (Fc_y1_2 * SincY1 - Fc_y2_2 * SincY2) + Fc_y3_2 * SincY3;
		float4 IdealI = Fc_i_2 * ((SincIIn != 0.0f) ? (sin(SincIIn) / SincIIn) : 1.0f);
		float4 IdealQ = Fc_q_2 * ((SincQIn != 0.0f) ? (sin(SincQIn) / SincQIn) : 1.0f);

		float4 FilterY = SincKernel * IdealY;		
		float4 FilterI = SincKernel * IdealI;
		float4 FilterQ = SincKernel * IdealQ;
		
		YAccum = YAccum + C * FilterY;
		IAccum = IAccum + C * cos(WT) * FilterI;
		QAccum = QAccum + C * sin(WT) * FilterQ;
	}
	
	float Y = YAccum.r + YAccum.g + YAccum.b + YAccum.a;
	float I = (IAccum.r + IAccum.g + IAccum.b + IAccum.a) * 2.0f;
	float Q = (QAccum.r + QAccum.g + QAccum.b + QAccum.a) * 2.0f;
	
	float3 YIQ = float3(Y, I, Q);

	float3 OutRGB = float3(dot(YIQ, float3(1.0f, 0.956f, 0.621f)), dot(YIQ, float3(1.0f, -0.272f, -0.647f)), dot(YIQ, float3(1.0f, -1.106f, 1.703f)));	
	
	return float4(OutRGB, BaseTexel.a);
}

//-----------------------------------------------------------------------------
// YIQ Decode Technique
//-----------------------------------------------------------------------------

technique DecodeTechnique
{
	pass Pass0
	{
		Lighting = FALSE;

		VertexShader = compile vs_3_0 vs_main();
		PixelShader  = compile ps_3_0 ps_main();
	}
}