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https://github.com/RetroDECK/Duckstation.git
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382 lines
9.1 KiB
GLSL
382 lines
9.1 KiB
GLSL
// PUBLIC DOMAIN CRT STYLED SCAN-LINE SHADER
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//
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// by Timothy Lottes
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//
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// This is more along the style of a really good CGA arcade monitor.
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// With RGB inputs instead of NTSC.
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// The shadow mask example has the mask rotated 90 degrees for less chromatic aberration.
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//
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// Left it unoptimized to show the theory behind the algorithm.
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//
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// It is an example what I personally would want as a display option for pixel art games.
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// Please take and use, change, or whatever.
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/*
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[configuration]
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[OptionRangeFloat]
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GUIName = Scanline Weight
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OptionName = hardScan
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MinValue = -20.0
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MaxValue = 0.0
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StepAmount = 1.0
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DefaultValue = -8.0
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[OptionRangeFloat]
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GUIName = Scanline Scale
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OptionName = hardPix
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MinValue = -20.0
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MaxValue = 0.0
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StepAmount = 1.0
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DefaultValue = -3.0
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[OptionRangeFloat]
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GUIName = Screen Warp X
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OptionName = warpX
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MinValue = 0.0
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MaxValue = 0.125
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StepAmount = 0.01
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DefaultValue = 0.031
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[OptionRangeFloat]
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GUIName = Screen Warp Y
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OptionName = warpY
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MinValue = 0.0
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MaxValue = 0.125
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StepAmount = 0.01
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DefaultValue = 0.041
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[OptionRangeFloat]
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GUIName = Mask Dark
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OptionName = maskDark
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MinValue = 0.0
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MaxValue = 2.0
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StepAmount = 0.1
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DefaultValue = 0.5
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[OptionRangeFloat]
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GUIName = Mask Light
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OptionName = maskLight
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MinValue = 0.0
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MaxValue = 2.0
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StepAmount = 0.1
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DefaultValue = 1.5
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[OptionRangeInteger]
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GUIName = Shadow Mask Type
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OptionName = shadowMask
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MinValue = 0
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MaxValue = 4
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StepAmount = 1
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DefaultValue = 3
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[OptionRangeFloat]
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GUIName = Brightess Boost
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OptionName = brightBoost
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MinValue = 0.0
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MaxValue = 2.0
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StepAmount = 0.05
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DefaultValue = 1.0
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[OptionRangeFloat]
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GUIName = Bloom Soft X
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OptionName = hardBloomPix
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MinValue = -2.0
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MaxValue = -0.5
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StepAmount = 0.1
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DefaultValue = -1.5
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[OptionRangeFloat]
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GUIName = Bloom Soft Y
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OptionName = hardBloomScan
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MinValue = -4.0
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MaxValue = -1.0
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StepAmount = 0.1
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DefaultValue = -2.0
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[OptionRangeFloat]
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GUIName = Bloom Amount
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OptionName = bloomAmount
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MinValue = 0.0
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MaxValue = 1.0
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StepAmount = 0.05
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DefaultValue = 0.15
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[OptionRangeFloat]
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GUIName = Filter Kernel Shape
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OptionName = shape
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MinValue = 0.0
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MaxValue = 10.0
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StepAmount = 0.05
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DefaultValue = 2.0
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[/configuration]
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*/
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//Uncomment to reduce instructions with simpler linearization
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//(fixes HD3000 Sandy Bridge IGP)
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#define SIMPLE_LINEAR_GAMMA
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#define DO_BLOOM
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// ------------- //
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// sRGB to Linear.
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// Assuming using sRGB typed textures this should not be needed.
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#ifdef SIMPLE_LINEAR_GAMMA
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float ToLinear1(float c)
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{
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return c;
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}
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float3 ToLinear(float3 c)
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{
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return c;
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}
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float3 ToSrgb(float3 c)
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{
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return pow(c, float3(1.0 / 2.2, 1.0 / 2.2, 1.0 / 2.2));
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}
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#else
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float ToLinear1(float c)
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{
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return(c<=0.04045) ? c/12.92 : pow((c + 0.055)/1.055, 2.4);
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}
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float3 ToLinear(float3 c)
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{
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return float3(ToLinear1(c.r), ToLinear1(c.g), ToLinear1(c.b));
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}
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// Linear to sRGB.
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// Assuming using sRGB typed textures this should not be needed.
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float ToSrgb1(float c)
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{
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return(c<0.0031308 ? c*12.92 : 1.055*pow(c, 0.41666) - 0.055);
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}
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float3 ToSrgb(float3 c)
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{
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return float3(ToSrgb1(c.r), ToSrgb1(c.g), ToSrgb1(c.b));
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}
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#endif
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// Nearest emulated sample given floating point position and texel offset.
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// Also zero's off screen.
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float3 Fetch(float2 pos,float2 off){
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pos=(floor(pos*GetResolution()+off)+float2(0.5,0.5))*GetInvResolution();
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#ifdef SIMPLE_LINEAR_GAMMA
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return ToLinear(GetOption(brightBoost) * pow(SampleLocation(pos.xy).rgb, float3(2.2, 2.2, 2.2)));
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#else
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return ToLinear(GetOption(brightBoost) * SampleLocation(pos.xy).rgb);
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#endif
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}
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// Distance in emulated pixels to nearest texel.
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float2 Dist(float2 pos)
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{
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pos = pos * (GetNativeSize() * GetWindowToViewportRatio());
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return -((pos - floor(pos)) - float2(0.5, 0.5));
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}
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// 1D Gaussian.
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float Gaus(float pos, float scale)
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{
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return exp2(scale*pow(abs(pos), GetOption(shape)));
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}
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// 3-tap Gaussian filter along horz line.
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float3 Horz3(float2 pos, float off)
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{
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float3 b = Fetch(pos, float2(-1.0, off));
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float3 c = Fetch(pos, float2( 0.0, off));
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float3 d = Fetch(pos, float2( 1.0, off));
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float dst = Dist(pos).x;
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// Convert distance to weight.
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float scale = GetOption(hardPix);
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float wb = Gaus(dst-1.0,scale);
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float wc = Gaus(dst+0.0,scale);
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float wd = Gaus(dst+1.0,scale);
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// Return filtered sample.
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return (b*wb+c*wc+d*wd)/(wb+wc+wd);
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}
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// 5-tap Gaussian filter along horz line.
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float3 Horz5(float2 pos,float off){
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float3 a = Fetch(pos,float2(-2.0, off));
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float3 b = Fetch(pos,float2(-1.0, off));
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float3 c = Fetch(pos,float2( 0.0, off));
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float3 d = Fetch(pos,float2( 1.0, off));
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float3 e = Fetch(pos,float2( 2.0, off));
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float dst = Dist(pos).x;
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// Convert distance to weight.
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float scale = GetOption(hardPix);
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float wa = Gaus(dst - 2.0, scale);
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float wb = Gaus(dst - 1.0, scale);
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float wc = Gaus(dst + 0.0, scale);
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float wd = Gaus(dst + 1.0, scale);
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float we = Gaus(dst + 2.0, scale);
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// Return filtered sample.
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return (a*wa+b*wb+c*wc+d*wd+e*we)/(wa+wb+wc+wd+we);
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}
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// 7-tap Gaussian filter along horz line.
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float3 Horz7(float2 pos,float off)
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{
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float3 a = Fetch(pos, float2(-3.0, off));
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float3 b = Fetch(pos, float2(-2.0, off));
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float3 c = Fetch(pos, float2(-1.0, off));
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float3 d = Fetch(pos, float2( 0.0, off));
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float3 e = Fetch(pos, float2( 1.0, off));
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float3 f = Fetch(pos, float2( 2.0, off));
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float3 g = Fetch(pos, float2( 3.0, off));
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float dst = Dist(pos).x;
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// Convert distance to weight.
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float scale = GetOption(hardBloomPix);
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float wa = Gaus(dst - 3.0, scale);
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float wb = Gaus(dst - 2.0, scale);
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float wc = Gaus(dst - 1.0, scale);
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float wd = Gaus(dst + 0.0, scale);
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float we = Gaus(dst + 1.0, scale);
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float wf = Gaus(dst + 2.0, scale);
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float wg = Gaus(dst + 3.0, scale);
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// Return filtered sample.
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return (a*wa+b*wb+c*wc+d*wd+e*we+f*wf+g*wg)/(wa+wb+wc+wd+we+wf+wg);
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}
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// Return scanline weight.
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float Scan(float2 pos, float off)
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{
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float dst = Dist(pos).y;
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return Gaus(dst + off, GetOption(hardScan));
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}
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// Return scanline weight for bloom.
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float BloomScan(float2 pos, float off)
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{
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float dst = Dist(pos).y;
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return Gaus(dst + off, GetOption(hardBloomScan));
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}
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// Allow nearest three lines to effect pixel.
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float3 Tri(float2 pos)
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{
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float3 a = Horz3(pos,-1.0);
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float3 b = Horz5(pos, 0.0);
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float3 c = Horz3(pos, 1.0);
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float wa = Scan(pos,-1.0);
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float wb = Scan(pos, 0.0);
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float wc = Scan(pos, 1.0);
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return a*wa + b*wb + c*wc;
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}
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// Small bloom.
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float3 Bloom(float2 pos)
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{
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float3 a = Horz5(pos,-2.0);
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float3 b = Horz7(pos,-1.0);
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float3 c = Horz7(pos, 0.0);
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float3 d = Horz7(pos, 1.0);
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float3 e = Horz5(pos, 2.0);
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float wa = BloomScan(pos,-2.0);
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float wb = BloomScan(pos,-1.0);
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float wc = BloomScan(pos, 0.0);
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float wd = BloomScan(pos, 1.0);
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float we = BloomScan(pos, 2.0);
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return a*wa+b*wb+c*wc+d*wd+e*we;
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}
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// Distortion of scanlines, and end of screen alpha.
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float2 Warp(float2 pos)
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{
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pos = pos*2.0-1.0;
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pos *= float2(1.0 + (pos.y*pos.y)*GetOption(warpX), 1.0 + (pos.x*pos.x)*GetOption(warpY));
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return pos*0.5 + 0.5;
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}
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// Shadow mask.
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float3 Mask(float2 pos)
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{
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float3 mask = float3(GetOption(maskDark), GetOption(maskDark), GetOption(maskDark));
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// Very compressed TV style shadow mask.
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if (GetOption(shadowMask) == 1)
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{
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float line_ = GetOption(maskLight);
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float odd = 0.0;
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if (fract(pos.x*0.166666666) < 0.5) odd = 1.0;
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if (fract((pos.y + odd) * 0.5) < 0.5) line_ = GetOption(maskDark);
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pos.x = fract(pos.x*0.333333333);
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if (pos.x < 0.333) mask.r = GetOption(maskLight);
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else if (pos.x < 0.666) mask.g = GetOption(maskLight);
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else mask.b = GetOption(maskLight);
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mask*=line_;
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}
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// Aperture-grille.
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else if (GetOption(shadowMask) == 2)
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{
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pos.x = fract(pos.x*0.333333333);
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if (pos.x < 0.333) mask.r = GetOption(maskLight);
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else if (pos.x < 0.666) mask.g = GetOption(maskLight);
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else mask.b = GetOption(maskLight);
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}
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// Stretched VGA style shadow mask (same as prior shaders).
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else if (GetOption(shadowMask) == 3)
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{
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pos.x += pos.y*3.0;
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pos.x = fract(pos.x*0.166666666);
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if (pos.x < 0.333) mask.r = GetOption(maskLight);
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else if (pos.x < 0.666) mask.g = GetOption(maskLight);
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else mask.b = GetOption(maskLight);
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}
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// VGA style shadow mask.
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else if (GetOption(shadowMask) == 4)
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{
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pos.xy = floor(pos.xy*float2(1.0, 0.5));
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pos.x += pos.y*3.0;
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pos.x = fract(pos.x*0.166666666);
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if (pos.x < 0.333) mask.r = GetOption(maskLight);
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else if (pos.x < 0.666) mask.g = GetOption(maskLight);
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else mask.b = GetOption(maskLight);
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}
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return mask;
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}
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void main()
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{
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float2 pos = Warp(GetCoordinates());
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float3 outColor = Tri(pos);
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#ifdef DO_BLOOM
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//Add Bloom
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outColor.rgb += Bloom(pos)*GetOption(bloomAmount);
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#endif
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if (GetOption(shadowMask) > 0)
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outColor.rgb *= Mask(gl_FragCoord.xy * 1.000001);
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SetOutput(float4(ToSrgb(outColor.rgb), 1.0));
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}
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