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https://github.com/italicsjenga/slang-shaders.git
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132 lines
4.3 KiB
Plaintext
132 lines
4.3 KiB
Plaintext
#version 450
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// This is a port of the NTSC encode/decode shader pair in MAME and MESS, modified to use only
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// one pass rather than an encode pass and a decode pass. It accurately emulates the sort of
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// signal decimation one would see when viewing a composite signal, though it could benefit from a
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// pre-pass to re-size the input content to more accurately reflect the actual size that would
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// be incoming from a composite signal source.
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//
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// To encode the composite signal, I convert the RGB value to YIQ, then subsequently evaluate
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// the standard NTSC composite equation. Four composite samples per RGB pixel are generated from
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// the incoming linearly-interpolated texels.
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//
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// The decode pass implements a Fixed Impulse Response (FIR) filter designed by MAME/MESS contributor
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// "austere" in matlab (if memory serves correctly) to mimic the behavior of a standard television set
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// as closely as possible. The filter window is 83 composite samples wide, and there is an additional
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// notch filter pass on the luminance (Y) values in order to strip the color signal from the luminance
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// signal prior to processing.
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//
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// - UltraMoogleMan [8/2/2013]
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layout(push_constant) uniform Push
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{
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vec4 SourceSize;
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vec4 OriginalSize;
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vec4 OutputSize;
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uint FrameCount;
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} params;
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#define float2 vec2
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#define float3 vec3
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#define float4 vec4
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//-----------------------------------------------------------------------------
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// NTSC Pixel Shader
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//-----------------------------------------------------------------------------
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const float AValue = 0.5f;
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const float BValue = 0.5f;
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const float CCValue = 3.5795454f;
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const float OValue = 0.0f;
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const float PValue = 1.0f;
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const float ScanTime = 52.6f;
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const float NotchHalfWidth = 1.0f;
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const float YFreqResponse = 6.0f;
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const float IFreqResponse = 1.2f;
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const float QFreqResponse = 0.6f;
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const float SignalOffset = 0.0f;
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//-----------------------------------------------------------------------------
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// Constants
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//-----------------------------------------------------------------------------
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const float PI = 3.1415927f;
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const float PI2 = 6.2830854f;
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const float4 YDot = float4(0.299f, 0.587f, 0.114f, 0.0f);
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const float4 IDot = float4(0.595716f, -0.274453f, -0.321263f, 0.0f);
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const float4 QDot = float4(0.211456f, -0.522591f, 0.311135f, 0.0f);
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const float3 RDot = float3(1.0f, 0.956f, 0.621f);
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const float3 GDot = float3(1.0f, -0.272f, -0.647f);
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const float3 BDot = float3(1.0f, -1.106f, 1.703f);
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const float4 OffsetX = float4(0.0f, 0.25f, 0.50f, 0.75f);
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const float4 NotchOffset = float4(0.0f, 1.0f, 2.0f, 3.0f);
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const int SampleCount = 64;
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const int HalfSampleCount = 32;
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float4 GetCompositeYIQ(sampler2D tex, float2 TexCoord, float2 size)
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{
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float2 PValueSourceTexel = float2(PValue / size.x, 0.0f);
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float2 C0 = TexCoord + PValueSourceTexel * OffsetX.x;
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float2 C1 = TexCoord + PValueSourceTexel * OffsetX.y;
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float2 C2 = TexCoord + PValueSourceTexel * OffsetX.z;
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float2 C3 = TexCoord + PValueSourceTexel * OffsetX.w;
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float4 Cx = float4(C0.x, C1.x, C2.x, C3.x);
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float4 Cy = float4(C0.y, C1.y, C2.y, C3.y);
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float4 Texel0 = texture(tex, C0);
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float4 Texel1 = texture(tex, C1);
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float4 Texel2 = texture(tex, C2);
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float4 Texel3 = texture(tex, C3);
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float4 HPosition = Cx;
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float4 VPosition = Cy;
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float4 Y = float4(dot(Texel0, YDot), dot(Texel1, YDot), dot(Texel2, YDot), dot(Texel3, YDot));
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float4 I = float4(dot(Texel0, IDot), dot(Texel1, IDot), dot(Texel2, IDot), dot(Texel3, IDot));
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float4 Q = float4(dot(Texel0, QDot), dot(Texel1, QDot), dot(Texel2, QDot), dot(Texel3, QDot));
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float W = PI2 * CCValue * ScanTime;
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float WoPI = W / PI;
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float HOffset = (BValue + SignalOffset) / WoPI;
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float VScale = (AValue * size.y) / WoPI;
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float4 T = HPosition + HOffset + VPosition * VScale;
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float4 TW = T * W;
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float4 CompositeYIQ = Y + I * cos(TW) + Q * sin(TW);
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return CompositeYIQ;
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}
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layout(std140, set = 0, binding = 0) uniform UBO
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{
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mat4 MVP;
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} global;
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#pragma stage vertex
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layout(location = 0) in vec4 Position;
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layout(location = 1) in vec2 TexCoord;
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layout(location = 0) out vec2 vTexCoord;
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void main()
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{
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gl_Position = global.MVP * Position;
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vTexCoord = TexCoord;
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}
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#pragma stage fragment
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layout(location = 0) in vec2 vTexCoord;
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layout(location = 0) out vec4 FragColor;
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layout(set = 0, binding = 2) uniform sampler2D Source;
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void main()
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{
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FragColor = GetCompositeYIQ(Source, vTexCoord, params.SourceSize.xy);
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} |