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306 lines
7.7 KiB
GLSL
306 lines
7.7 KiB
GLSL
#version 150
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// 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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#define hardScan -8.0
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#define hardPix -3.0
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#define warpX 0.031
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#define warpY 0.041
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#define maskDark 0.5
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#define maskLight 1.5
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#define scaleInLinearGamma 1.0
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#define shadowMask 3.0
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#define brightBoost 1.0
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#define hardBloomPix -1.5
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#define hardBloomScan -2.0
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#define bloomAmount 0.4
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#define shape 2.0
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uniform sampler2D source[];
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uniform vec4 sourceSize[];
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in Vertex {
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vec2 vTexCoord;
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};
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out vec4 FragColor;
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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 1
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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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vec3 ToLinear(vec3 c)
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{
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return c;
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}
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vec3 ToSrgb(vec3 c)
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{
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return pow(c, vec3(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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if (scaleInLinearGamma == 0)
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return c;
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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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vec3 ToLinear(vec3 c)
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{
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if (scaleInLinearGamma==0)
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return c;
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return vec3(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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if (scaleInLinearGamma == 0)
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return c;
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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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vec3 ToSrgb(vec3 c)
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{
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if (scaleInLinearGamma == 0)
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return c;
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return vec3(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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vec3 Fetch(vec2 pos,vec2 off){
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pos=(floor(pos*sourceSize[0].xy+off)+vec2(0.5,0.5))/sourceSize[0].xy;
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#ifdef SIMPLE_LINEAR_GAMMA
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return ToLinear(brightBoost * pow(texture(source[0],pos.xy).rgb, vec3(2.2)));
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#else
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return ToLinear(brightBoost * texture(source[0],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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vec2 Dist(vec2 pos)
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{
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pos = pos*sourceSize[0].xy;
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return -((pos - floor(pos)) - vec2(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), shape));
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}
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// 3-tap Gaussian filter along horz line.
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vec3 Horz3(vec2 pos, float off)
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{
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vec3 b = Fetch(pos, vec2(-1.0, off));
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vec3 c = Fetch(pos, vec2( 0.0, off));
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vec3 d = Fetch(pos, vec2( 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 = 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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vec3 Horz5(vec2 pos,float off){
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vec3 a = Fetch(pos,vec2(-2.0, off));
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vec3 b = Fetch(pos,vec2(-1.0, off));
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vec3 c = Fetch(pos,vec2( 0.0, off));
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vec3 d = Fetch(pos,vec2( 1.0, off));
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vec3 e = Fetch(pos,vec2( 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 = 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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vec3 Horz7(vec2 pos,float off)
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{
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vec3 a = Fetch(pos, vec2(-3.0, off));
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vec3 b = Fetch(pos, vec2(-2.0, off));
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vec3 c = Fetch(pos, vec2(-1.0, off));
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vec3 d = Fetch(pos, vec2( 0.0, off));
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vec3 e = Fetch(pos, vec2( 1.0, off));
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vec3 f = Fetch(pos, vec2( 2.0, off));
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vec3 g = Fetch(pos, vec2( 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 = 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(vec2 pos, float off)
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{
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float dst = Dist(pos).y;
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return Gaus(dst + off, hardScan);
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}
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// Return scanline weight for bloom.
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float BloomScan(vec2 pos, float off)
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{
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float dst = Dist(pos).y;
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return Gaus(dst + off, hardBloomScan);
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}
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// Allow nearest three lines to effect pixel.
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vec3 Tri(vec2 pos)
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{
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vec3 a = Horz3(pos,-1.0);
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vec3 b = Horz5(pos, 0.0);
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vec3 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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vec3 Bloom(vec2 pos)
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{
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vec3 a = Horz5(pos,-2.0);
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vec3 b = Horz7(pos,-1.0);
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vec3 c = Horz7(pos, 0.0);
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vec3 d = Horz7(pos, 1.0);
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vec3 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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vec2 Warp(vec2 pos)
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{
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pos = pos*2.0-1.0;
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pos *= vec2(1.0 + (pos.y*pos.y)*warpX, 1.0 + (pos.x*pos.x)*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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vec3 Mask(vec2 pos)
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{
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vec3 mask = vec3(maskDark, maskDark, maskDark);
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// Very compressed TV style shadow mask.
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if (shadowMask == 1.0)
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{
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float line = 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 = maskDark;
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pos.x = fract(pos.x*0.333333333);
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if (pos.x < 0.333) mask.r = maskLight;
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else if (pos.x < 0.666) mask.g = maskLight;
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else mask.b = maskLight;
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mask*=line;
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}
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// Aperture-grille.
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else if (shadowMask == 2.0)
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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 = maskLight;
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else if (pos.x < 0.666) mask.g = maskLight;
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else mask.b = maskLight;
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}
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// Stretched VGA style shadow mask (same as prior shaders).
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else if (shadowMask == 3.0)
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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 = maskLight;
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else if (pos.x < 0.666) mask.g = maskLight;
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else mask.b = maskLight;
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}
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// VGA style shadow mask.
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else if (shadowMask == 4.0)
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{
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pos.xy = floor(pos.xy*vec2(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 = maskLight;
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else if (pos.x < 0.666) mask.g = maskLight;
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else mask.b = 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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FragColor = vec4(Bloom(vTexCoord)*bloomAmount, 1.0);
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} |