198 lines
4.6 KiB
Text
198 lines
4.6 KiB
Text
#version 450
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/**
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* Practical Elliptical Texture Filtering on the GPU
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* Copyright 2010-2011 Pavlos Mavridis, All rights reserved.
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*
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* Version: 0.6 - 12 / 7 / 2011 (DD/MM/YY)
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*/
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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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float distortion;
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} params;
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#pragma parameter distortion "EWA Curvature" 0.15 0.0 1.0 0.01
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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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//{========= TEXTURE FILTERING (EWA) PARAMETERS =========
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#define MAX_ECCENTRICITY 1
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#define FILTER_WIDTH 0.8
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#define FILTER_SHARPNESS 1.0
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#define TEXELS_PER_PIXEL 1.0
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#define TEXEL_LIMIT 32
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#define FILTER_FUNC gaussFilter
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//}======================================================
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#define M_PI 3.14159265358979323846
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#define SourceImage Source
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//{========================= FILTER FUNCTIONS =======================
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// We only use the Gaussian filter function. The other filters give
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// very similar results.
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float boxFilter(float r2){
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return 1.0;
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}
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float gaussFilter(float r2){
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float alpha = FILTER_SHARPNESS;
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return exp(-alpha * r2);
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}
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float triFilter(float r2){
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float alpha = FILTER_SHARPNESS;
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float r= sqrt(r2);
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return max(0, 1.-r);///alpha);
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}
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float sinc(float x){
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return sin(M_PI*x)/(M_PI*x);
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}
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float lanczosFilter(float r2){
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if (r2==0)
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return 1.;
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float r= sqrt(r2);
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return sinc(r)*sinc(r/1.3);
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}
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//catmull-rom filter
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float crFilter(float r2){
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float r = sqrt(r2);
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return (r>=2.)?.0:(r<1.)?(3.*r*r2-5.*r2+2.):(-r*r2+5.*r2-8*r+4.);
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}
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float quadraticFilter(float r2){
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float a = FILTER_SHARPNESS;
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return 1.0 - r2/(a*a);
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}
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float cubicFilter(float r2){
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float a = FILTER_SHARPNESS;
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float r = sqrt(r2);
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return 1.0 - 3*r2/(a*a) + 2*r*r2/(a*a*a);
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}
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//}
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//==================== EWA ( reference / 2-tex / 4-tex) ====================
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/**
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* EWA filter
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* Adapted from an ANSI C implementation from Matt Pharr
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*/
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vec4 ewaFilter(sampler2D Source, vec2 p0, vec2 du, vec2 dv, int scale){
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vec4 foo = texture(Source,p0);
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//don't bother with elliptical filtering if the scale is very small
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if(scale<2)
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return foo;
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p0 -=vec2(0.5,0.5)/scale;
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vec2 p = scale * p0;
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float ux = FILTER_WIDTH * du.s * scale;
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float vx = FILTER_WIDTH * du.t * scale;
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float uy = FILTER_WIDTH * dv.s * scale;
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float vy = FILTER_WIDTH * dv.t * scale;
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// compute ellipse coefficients
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// A*x*x + B*x*y + C*y*y = F.
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float A = vx*vx+vy*vy+1;
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float B = -2*(ux*vx+uy*vy);
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float C = ux*ux+uy*uy+1;
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float F = A*C-B*B/4.;
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// Compute the ellipse's (u,v) bounding box in texture space
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float bbox_du = 2. / (-B*B+4.0*C*A) * sqrt((-B*B+4.0*C*A)*C*F);
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float bbox_dv = 2. / (-B*B+4.0*C*A) * sqrt(A*(-B*B+4.0*C*A)*F);
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//the ellipse bbox
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int u0 = int(floor(p.s - bbox_du));
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int u1 = int(ceil (p.s + bbox_du));
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int v0 = int(floor(p.t - bbox_dv));
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int v1 = int(ceil (p.t + bbox_dv));
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// Heckbert MS thesis, p. 59; scan over the bounding box of the ellipse
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// and incrementally update the value of Ax^2+Bxy*Cy^2; when this
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// value, q, is less than F, we're inside the ellipse so we filter
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// away..
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vec4 num= vec4(0., 0., 0., 1.);
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float den = 0;
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float ddq = 2 * A;
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float U = u0 - p.s;
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for (int v = v0; v <= v1; ++v) {
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float V = v - p.t;
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float dq = A*(2*U+1) + B*V;
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float q = (C*V + B*U)*V + A*U*U;
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for (int u = u0; u <= u1; ++u) {
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if (q < F)
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{
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float r2 = q / F;
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float weight = FILTER_FUNC(r2);
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num += weight* texture(Source, vec2(u+0.5,v+0.5)/scale);
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den += weight;
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}
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q += dq;
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dq += ddq;
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}
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}
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vec4 color = num*(1./den);
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return color;
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}
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vec4 texture2DEWA(sampler2D tex, vec2 coords){
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vec2 du = dFdx(coords);
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vec2 dv = dFdy(coords);
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int scale = textureSize(tex, 0).x;
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return ewaFilter(tex, coords, du, dv, scale );
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}
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vec2 radialDistortion(vec2 coord) {
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vec2 cc = coord - vec2(0.5);
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float dist = dot(cc, cc) * params.distortion;
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return coord + cc * (1.0 - dist) * dist;
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}
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void main()
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{
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FragColor = texture2DEWA(SourceImage,radialDistortion(vTexCoord));
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}
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