136 lines
3.1 KiB
C
136 lines
3.1 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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#include <math.h>
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const char *shades = ".:!*oe&#%@";
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void vsub(double *v1, double *v2, double *s) {
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s[0] = v1[0] - v2[0];
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s[1] = v1[1] - v2[1];
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s[2] = v1[2] - v2[2];
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}
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double normalize(double * v) {
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double len = sqrt(v[0]*v[0] + v[1]*v[1] + v[2]*v[2]);
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v[0] /= len; v[1] /= len; v[2] /= len;
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return len;
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}
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double dot(double *x, double *y) {
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return x[0]*y[0] + x[1]*y[1] + x[2]*y[2];
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}
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double * cross(double x[3], double y[3], double s[3]) {
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s[0] = x[1] * y[2] - x[2] * y[1];
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s[1] = x[2] * y[0] - x[0] * y[2];
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s[2] = x[0] * y[1] - x[1] * y[0];
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return s;
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}
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double* madd(double *x, double *y, double d, double *r) {
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r[0] = x[0] + y[0] * d;
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r[1] = x[1] + y[1] * d;
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r[2] = x[2] + y[2] * d;
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return r;
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}
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double v000[] = { -4, -3, -2 };
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double v100[] = { 4, -3, -2 };
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double v010[] = { -4, 3, -2 };
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double v110[] = { 4, 3, -2 };
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double v001[] = { -4, -3, 2 };
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double v101[] = { 4, -3, 2 };
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double v011[] = { -4, 3, 2 };
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double v111[] = { 4, 3, 2 };
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typedef struct {
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double * v[4];
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double norm[3];
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} face_t;
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face_t f[] = {
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{ { v000, v010, v110, v100 }, { 0, 0, -1 } },
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{ { v001, v011, v111, v101 }, { 0, 0, 1 } },
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{ { v000, v010, v011, v001 }, { -1, 0, 0 } },
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{ { v100, v110, v111, v101 }, { 1, 0, 0 } },
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{ { v000, v100, v101, v001 }, { 0, -1, 0 } },
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{ { v010, v110, v111, v011 }, { 0, 1, 0 } },
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};
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int in_range(double x, double x0, double x1) {
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return (x - x0) * (x - x1) <= 0;
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}
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int face_hit(face_t *face, double src[3], double dir[3], double hit[3], double *d)
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{
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int i;
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double dist;
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for (i = 0; i < 3; i++)
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if (face->norm[i])
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dist = (face->v[0][i] - src[i]) / dir[i];
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madd(src, dir, dist, hit);
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*d = fabs(dot(dir, face->norm) * dist);
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if (face->norm[0]) {
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return in_range(hit[1], face->v[0][1], face->v[2][1]) &&
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in_range(hit[2], face->v[0][2], face->v[2][2]);
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}
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else if (face->norm[1]) {
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return in_range(hit[0], face->v[0][0], face->v[2][0]) &&
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in_range(hit[2], face->v[0][2], face->v[2][2]);
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}
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else if (face->norm[2]) {
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return in_range(hit[0], face->v[0][0], face->v[2][0]) &&
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in_range(hit[1], face->v[0][1], face->v[2][1]);
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}
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return 0;
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}
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int main()
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{
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int i, j, k;
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double eye[3] = { 7, 7, 6 };
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double dir[3] = { -1, -1, -1 }, orig[3] = {0, 0, 0};
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double hit[3], dx[3], dy[3] = {0, 0, 1}, proj[3];
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double d, *norm, dbest, b;
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double light[3] = { 6, 8, 6 }, ldist[3], decay, strength = 10;
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normalize(cross(eye, dy, dx));
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normalize(cross(eye, dx, dy));
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for (i = -10; i <= 17; i++) {
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for (j = -35; j < 35; j++) {
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vsub(orig, orig, proj);
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madd(madd(proj, dx, j / 6., proj), dy, i/3., proj);
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vsub(proj, eye, dir);
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dbest = 1e100;
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norm = 0;
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for (k = 0; k < 6; k++) {
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if (!face_hit(f + k, eye, dir, hit, &d)) continue;
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if (dbest > d) {
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dbest = d;
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norm = f[k].norm;
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}
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}
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if (!norm) {
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putchar(' ');
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continue;
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}
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vsub(light, hit, ldist);
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decay = normalize(ldist);
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b = dot(norm, ldist) / decay * strength;
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if (b < 0) b = 0;
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else if (b > 1) b = 1;
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b += .2;
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if (b > 1) b = 0;
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else b = 1 - b;
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putchar(shades[(int)(b * (sizeof(shades) - 2))]);
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}
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putchar('\n');
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}
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return 0;
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}
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