80 lines
2.0 KiB
C++
80 lines
2.0 KiB
C++
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// minray > minray.ppm
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#include <math.h>
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#include <stdio.h>
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#include <stdlib.h>
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typedef int i;
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typedef float f;
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struct v {
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f x, y, z;
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v operator+(v r) { return v(x + r.x, y + r.y, z + r.z); }
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v operator*(f r) { return v(x * r, y * r, z * r); }
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f operator%(v r) { return x * r.x + y * r.y + z * r.z; }
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v() {}
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v operator^(v r) {
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return v(y * r.z - z * r.y, z * r.x - x * r.z, x * r.y - y * r.x);
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}
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v(f a, f b, f c) {
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x = a;
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y = b;
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z = c;
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}
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v operator!() { return *this * (1 / sqrt(*this % *this)); }
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};
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i G[] = {247570, 280596, 280600, 249748, 18578, 18577, 231184, 16, 16};
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f R() { return (f)rand() / RAND_MAX; }
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i T(v o, v d, f &t, v &n) {
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t = 1e9;
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i m = 0;
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f p = -o.z / d.z;
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if (.01 < p)
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t = p, n = v(0, 0, 1), m = 1;
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for (i k = 19; k--;)
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for (i j = 9; j--;)
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if (G[j] & 1 << k) {
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v p = o + v(-k, 0, -j - 4);
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f b = p % d, c = p % p - 1, q = b * b - c;
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if (q > 0) {
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f s = -b - sqrt(q);
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if (s < t && s > .01)
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t = s, n = !(p + d * t), m = 2;
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}
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}
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return m;
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}
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v S(v o, v d) {
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f t;
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v n;
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i m = T(o, d, t, n);
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if (!m)
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return v(.7, .6, 1) * pow(1 - d.z, 4);
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v h = o + d * t, l = !(v(9 + R(), 9 + R(), 16) + h * -1),
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r = d + n * (n % d * -2);
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f b = l % n;
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if (b < 0 || T(h, l, t, n))
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b = 0;
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f p = pow(l % r * (b > 0), 99);
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if (m & 1) {
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h = h * .2;
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return ((i)(ceil(h.x) + ceil(h.y)) & 1 ? v(3, 1, 1) : v(3, 3, 3)) *
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(b * .2 + .1);
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}
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return v(p, p, p) + S(h, r) * .5;
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}
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i main() {
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printf("P6 512 512 255 ");
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v g = !v(-6, -16, 0), a = !(v(0, 0, 1) ^ g) * .002, b = !(g ^ a) * .002,
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c = (a + b) * -256 + g;
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for (i y = 512; y--;)
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for (i x = 512; x--;) {
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v p(13, 13, 13);
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for (i r = 64; r--;) {
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v t = a * (R() - .5) * 99 + b * (R() - .5) * 99;
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p = S(v(17, 16, 8) + t,
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!(t * -1 + (a * (R() + x) + b * (y + R()) + c) * 16)) *
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3.5 +
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p;
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}
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printf("%c%c%c", (i)p.x, (i)p.y, (i)p.z);
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}
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}
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