105 lines
2.1 KiB
C
105 lines
2.1 KiB
C
#include "ray.h"
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#include "map.h"
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#include <math.h>
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float v2_cross(v2 a, v2 b) {
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return fabs(a.x * b.y - a.y * b.x);
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}
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float v2_len(v2 a) {
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return sqrt(a.x * a.x + a.y * a.y);
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}
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float v2_dist(v2 a, v2 b) {
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return sqrt(v2_square_dist(a, b));
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}
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float v2_square_dist(v2 a, v2 b) {
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return pow(a.x - b.x, 2) + pow(a.y - b.y, 2);
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}
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uint32_t cast_ray(v2 pos, float theta, v2* hit_pos) {
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const v2i move = {
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sign(cos(theta)),
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sign(sin(theta)),
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};
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const v2i offset = {
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move.x == -1 ? 1 : 0,
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move.y == -1 ? 1 : 0
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};
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const float tanc = tan(theta);
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const float cotc = tan(PIH - (theta));
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v2i posi = {
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(int)pos.x + offset.x,
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(int)pos.y + offset.y
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};
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bool fx = false;
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uint32_t vx = 0;
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float x;
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while (!fx) {
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posi.y += move.y;
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x = cotc * (posi.y - pos.y) + pos.x;
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if (fabs(x) - pos.x >= MAP_SIZE) break;
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vx = value((int)x, posi.y - offset.y);
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if (vx != 0) {
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fx = true;
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}
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}
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bool fy = false;
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uint32_t vy = 0;
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float y;
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while (!fy) {
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posi.x += move.x;
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y = tanc * (posi.x - pos.x) + pos.y;
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if (fabs(y) - pos.y >= MAP_SIZE) break;
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vy = value(posi.x - offset.x, (int)y);
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if (vy != 0) {
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fy = true;
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}
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}
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uint32_t hit;
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if (!fx && !fy) {
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hit = 0;
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hit_pos->x = pos.x + 1000 * move.x;
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hit_pos->y = pos.y + 1000 * move.y;
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return false;
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} else if (fx && !fy) {
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hit = vx;
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hit_pos->x = x;
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hit_pos->y = posi.y;
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} else if (fy && !fx) {
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hit = vy;
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hit_pos->x = posi.x;
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hit_pos->y = y;
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} else {
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const v2 posx = {x, posi.y};
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const v2 posy = {posi.x, y};
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if (v2_square_dist(posx, pos) < v2_square_dist(posy, pos)) {
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hit = vx;
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hit_pos->x = x;
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hit_pos->y = posi.y;
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} else {
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hit = vy;
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hit_pos->x = posi.x;
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hit_pos->y= y;
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}
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}
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return hit;
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}
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