54 lines
1 KiB
GLSL
54 lines
1 KiB
GLSL
#version 330
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out vec4 fragColor;
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uniform vec2 res;
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uniform float time;
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const float sharpness = 300;
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const float PI = 3.14159265358979323846;
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mat2 rot(float a) {
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return mat2(
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cos(a), -sin(a),
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sin(a), cos(a)
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);
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}
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float poly(float n, vec2 m, float r, float rt, vec2 p) {
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vec2 diff = (m - p) * rot(rt);
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float d = length(diff);
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float alpha = PI / n;
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float gamma = mod(abs(atan(diff.x, diff.y)), alpha*2);
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if (gamma > alpha)
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gamma -= 2*alpha;
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float r2 = r * cos(alpha) / cos(gamma);
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return clamp((r2 - d)*sharpness, 0.0, 1.0);
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}
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float poly_d(float n, vec2 m, float r, float rt, vec2 p) {
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return poly(n, m, r, rt, p) - poly(n, m, r - 1/sharpness, rt, p);
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}
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void main(void) {
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vec2 m = res/2;
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float s = min(m.x, m.y);
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vec2 p = (gl_FragCoord.xy - m) / s;
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float scene = 0;
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float c;
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c = poly_d(5 - 3*cos(time/1000), vec2(0, 0), 0.5, PI * time/1000, p);
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scene = abs(scene - c);
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c = poly_d(5 - 3*cos(time/1000), vec2(0, 0), 0.5, -PI * time/1000, p);
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scene = abs(scene - c);
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fragColor = vec4(vec3(1, 1, 1) * scene, 1);
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}
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