54 lines
1.4 KiB
GLSL
54 lines
1.4 KiB
GLSL
float chebyshev(float x, int n){
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const int MAX_POWER = 16;
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vec2 tvec = vec2( 1., x);
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mat2 m = mat2 (0., -1., 1., 2.*x);
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for( int i = 2; i < MAX_POWER; i += 1){
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if( i > n ) return tvec.y;
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tvec = m*tvec;
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}
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return tvec.y;
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}
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//https://github.com/hughsk/glsl-hsv2rgb/blob/master/index.glsl
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vec3 hsv2rgb(vec3 c) {
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vec4 K = vec4(1.0, 2.0 / 3.0, 1.0 / 3.0, 3.0);
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vec3 p = abs(fract(c.xxx + K.xyz) * 6.0 - K.www);
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return c.z * mix(K.xxx, clamp(p - K.xxx, 0.0, 1.0), c.y);
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}
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void mainImage( out vec4 fragColor, in vec2 fragCoord )
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{
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vec2 uv = fragCoord / max(iResolution.x, iResolution.y);
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uv *= 2.5;
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uv.x -= 1.2;
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uv.y -= 0.5;
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float timex = iTime * .21;
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float tx = cos(timex)*chebyshev(uv.x, 2) + sin(timex)* chebyshev(uv.x, 5) ;
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float timey = iTime * 0.2;
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float ty = cos(timey)*chebyshev(uv.y, 3) + sin(timey)* chebyshev(uv.y, 7) ;
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float t2 = iTime * .5;
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float csigma = cos(t2);
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float s2sigma = 1. - csigma*csigma;
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//next formula was taken from this paper
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//http://boj.pntic.mec.es/~jcastine/Trabajos%20matematicos_archivos/cmj122-127.pdf
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float b = tx*tx + ty*ty - 2.0*tx*ty*csigma + s2sigma;
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float w = 3.*fwidth(b);
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//float w = .2;
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b *= 2.;
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float bFloor = floor(b);
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b = smoothstep(w,0.,abs(fract(b) -.5))/fwidth(b);
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//b*= step(abs(uv.x), 1.);
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//b*= step(abs(uv.y), 1.);
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vec3 color = hsv2rgb(vec3(bFloor/10.+fract(iTime*0.1),1.,1.));
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color *= b;
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fragColor = vec4(color, 1.0);
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}
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// https://www.shadertoy.com/view/MtBBRG
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