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#include "renderer.h"
#include "screen.h"
#include <math.h>
#define PI 3.14159265358979323846
#define PIH 1.57079632679489661923
#define PI2 6.28318530718
void init_camera(Camera* camera) {
camera->x = 3;
camera->y = 3;
camera->angle = PI / 4;
}
typedef struct {
float x, y;
} v2;
typedef struct {
int x, y;
} v2i;
#define MOVE_SPEED 1
#define ROTATE_SPEED PI / 2
void update_camera(Camera* camera, Screen* screen) {
double rotate = 0;
if (key_pressed(screen, SDL_SCANCODE_LEFT))
rotate -= ROTATE_SPEED;
if (key_pressed(screen, SDL_SCANCODE_RIGHT))
rotate += ROTATE_SPEED;
rotate *= screen->delta;
rotate += camera->angle;
while (rotate >= PI2) rotate -= PI2;
while (rotate < 0) rotate += PI2;
camera->angle = rotate;
v2 forward = { cos(camera->angle), sin(camera->angle) };
v2 left = { forward.y, -forward.x };
v2 move = { 0, 0 };
if (key_pressed(screen, SDL_SCANCODE_W)) {
move.x += forward.x;
move.y += forward.y;
}
if (key_pressed(screen, SDL_SCANCODE_S)) {
move.x -= forward.x;
move.y -= forward.y;
}
if (key_pressed(screen, SDL_SCANCODE_A)) {
move.x += left.x;
move.y += left.y;
}
if (key_pressed(screen, SDL_SCANCODE_D)) {
move.x -= left.x;
move.y -= left.y;
}
camera->x += move.x * MOVE_SPEED * screen->delta;
camera->y += move.y * MOVE_SPEED * screen->delta;
}
#define MAP_SIZE 8
static uint8_t MAPDATA[MAP_SIZE * MAP_SIZE] = {
1, 1, 1, 1, 1, 1, 1, 1,
1, 0, 0, 0, 0, 0, 0, 1,
1, 0, 0, 0, 0, 3, 0, 1,
1, 0, 0, 0, 0, 0, 0, 1,
1, 0, 2, 0, 4, 4, 0, 1,
1, 0, 0, 0, 4, 0, 0, 1,
1, 0, 3, 0, 0, 0, 0, 1,
1, 1, 1, 1, 1, 1, 1, 1,
};
static void verline(Screen* screen, int x, int y0, int y1, uint32_t color) {
for (int y = y0; y <= y1; y++) {
screen->pixels[(y * screen->width) + x] = color;
}
}
static float v2_cross(v2 a, v2 b) {
return fabs(a.x * b.y - a.y * b.x);
}
static float v2_len(v2 a) {
return sqrt(a.x * a.x + a.y * a.y);
}
static float v2_square_dist(v2 a, v2 b) {
return pow(a.x - b.x, 2) + pow(a.y - b.y, 2);
}
#define min(a, b) ((a) < (b) ? (a) : (b))
#define max(a, b) ((a) > (b) ? (a) : (b))
#define sign(a) ((a) < 0 ? -1 : 1)
#define value(x, y) (MAPDATA[(x) + MAP_SIZE * (y)])
void render(Screen* screen, const Camera* camera) {
const double fov = PI / 3;
const v2 cam_right = {
-sin(camera->angle),
cos(camera->angle)
};
const v2 pos = {
camera->x,
camera->y
};
for (int sx = 0; sx < screen->width; sx++) {
const float xcam = (2 * (sx / (float) (screen->width))) - 1;
const float change = fov * atan(xcam);
const v2i move = {
sign(cos(camera->angle + change)),
sign(sin(camera->angle + change)),
};
const v2i offset = {
move.x == -1 ? 1 : 0,
move.y == -1 ? 1 : 0
};
const float tanc = tan(camera->angle + change);
const float cotc = tan(PIH - (camera->angle + change));
v2i posi = {
(int)pos.x + offset.x,
(int)pos.y + offset.y
};
bool fx = false;
uint32_t vx = 0;
float x;
while (!fx) {
posi.y += move.y;
x = cotc * (posi.y - pos.y) + pos.x;
if (fabs(x) - pos.x >= MAP_SIZE) break;
vx = value((int)x, posi.y - offset.y);
if (vx != 0) {
fx = true;
}
}
bool fy = false;
uint32_t vy = 0;
float y;
while (!fy) {
posi.x += move.x;
y = tanc * (posi.x - pos.x) + pos.y;
if (fabs(y) - pos.y >= MAP_SIZE) break;
vy = value(posi.x - offset.x, (int)y);
if (vy != 0) {
fy = true;
}
}
uint32_t hit;
if (!fx && !fy) {
hit = 0;
x = pos.x + 1000 * move.x;
y = pos.y + 1000 * move.y;
} else if (fx && !fy) {
hit = vx;
y = posi.y;
} else if (fy && !fx) {
hit = vy;
x = posi.x;
} else {
const v2 posx = {x, posi.y};
const v2 posy = {posi.x, y};
if (v2_square_dist(posx, pos) < v2_square_dist(posy, pos)) {
hit = vx;
y = posi.y;
} else {
hit = vy;
x = posi.x;
}
}
const v2 relative = {
x - pos.x,
y - pos.y
};
float len = v2_cross(relative, cam_right) / v2_len(cam_right);
if (len < 0.00001) len = 0.00001;
uint32_t color;
switch (hit) {
case 1: color = 0xFF0000FF; break;
case 2: color = 0x00FF00FF; break;
case 3: color = 0x0000FFFF; break;
case 4: color = 0xFF00FFFF; break;
case 5: color = 0x00FFFFFF; break;
default: color = 0x000000FF; break;
}
const int
h = (int) (screen->height / len),
y0 = max((screen->height / 2) - (h / 2), 0),
y1 = min((screen->height / 2) + (h / 2), screen->height - 1);
verline(screen, sx, 0, y0, 0x202020FF);
verline(screen, sx, y0, y1, color);
verline(screen, sx, y1, screen->height - 1, 0x505050FF);
}
}
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