C terminal ray caster

raycast.c

// Compile using any C compiler (except MSVC):
//
// cc raycast.c -lm -O3 -o raycast


#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#ifdef _WIN32
    #include <windows.h>
#else
    #include <sys/ioctl.h>
    #include <termios.h>
    #include <unistd.h>
#endif

#ifdef _WIN32
    static DWORD og_stdin_flags;
#else
    static struct termios og_stdin_flags;
#endif

void term_deinit(void) {
    #ifdef _WIN32
        HANDLE in_h = GetStdHandle(STD_INPUT_HANDLE);
        SetConsoleMode(in_h, og_stdin_flags);
    #else
        tcsetattr(STDIN_FILENO, TCSANOW, &og_stdin_flags);
    #endif
}

void term_init(void) {
    #ifdef _WIN32
        DWORD mode;
        HANDLE in_h = GetStdHandle(STD_INPUT_HANDLE);
        GetConsoleMode(in_h, &og_stdin_flags);
        GetConsoleMode(in_h, &mode);
        mode &= ~(ENABLE_LINE_INPUT | ENABLE_ECHO_INPUT);
        mode |= ENABLE_PROCESSED_INPUT;
        if(!SetConsoleMode(in_h, mode)) {
            fprintf(stderr, "Failed to configure terminal input");
            abort();
        }
    #else
        if(tcgetattr(STDIN_FILENO, &og_stdin_flags) == -1) {
            fprintf(stderr, "Failed to configure terminal input");
            abort();
        }
        struct termios stdin_flags = og_stdin_flags;
        stdin_flags.c_lflag &= ~(ICANON | ECHO);
        stdin_flags.c_cc[VMIN] = 1;
        stdin_flags.c_cc[VTIME] = 0;
        if(tcsetattr(STDIN_FILENO, TCSANOW, &stdin_flags) == -1) {
            fprintf(stderr, "Failed to configure terminal input");
            abort();
        }
    #endif
    setvbuf(stdin, NULL, _IONBF, 0);
    atexit(&term_deinit);
}

void get_term_size(unsigned int *columns, unsigned int *rows) {
    #ifdef _WIN32
        CONSOLE_SCREEN_BUFFER_INFO t_info;
        HANDLE out_h = GetStdHandle(STD_OUTPUT_HANDLE);
        if(!GetConsoleScreenBufferInfo(out_h, &t_info)) {
            fprintf(stderr, "Failed to get terminal dimensions");
            abort();
        }
        *columns = t_info.srWindow.Right - t_info.srWindow.Left + 1;
        *rows = t_info.srWindow.Bottom - t_info.srWindow.Top + 1;
    #else
        struct winsize t_size;
        if(ioctl(STDOUT_FILENO, TIOCGWINSZ, &t_size) == -1) {
            fprintf(stderr, "Failed to get terminal dimensions");
            abort();
        }
        *colums = t_size.ws_col;
        *rows = t_size.ws_row;
    #endif
}

void term_reset(void) {
    #ifdef _WIN32
        HANDLE out_h = GetStdHandle(STD_OUTPUT_HANDLE);
        COORD home_coords = { 0, 0 };
        SetConsoleCursorPosition(out_h, home_coords);
    #else
        printf("\033[H");
    #endif
}

#define WORLD_WIDTH 16
#define WORLD_HEIGHT 16
static const char world_data[WORLD_WIDTH * WORLD_HEIGHT] = {
    1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
    1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,
    1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,
    1,0,0,1,1,0,0,0,0,0,0,0,0,0,0,1,
    1,0,0,1,1,0,0,0,0,0,0,0,0,0,0,1,
    1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,
    1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,
    1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,
    1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,
    1,0,0,0,0,0,1,1,0,0,0,0,0,0,0,1,
    1,0,0,0,0,0,1,1,0,0,0,0,0,0,0,1,
    1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,
    1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,
    1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,
    1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,
    1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1
};

char world_data_at(double x, double y) {
    unsigned int tx = x < 0.0? 0 : x > WORLD_WIDTH? 0 : (unsigned int) x;
    unsigned int ty = y < 0.0? 0 : x > WORLD_HEIGHT? 0 : (unsigned int) y;
    return world_data[tx + ty * WORLD_WIDTH];
}

#define TAU 6.2831853071
#define FOV TAU / 3.0
#define RAY_STEP 0.01
#define MAX_RAY_DEPTH 8.0
#define MIN_WALL_DIST 0.5

double cast_ray(double sx, double sy, double a) {
    double dx = cos(a) * RAY_STEP;
    double dy = sin(a) * RAY_STEP;
    double x = sx;
    double y = sy;
    double d = 0.0;
    for(;;) {
        char tile = world_data_at(x, y);
        if(tile != 0) { break; }
        if(d >= MAX_RAY_DEPTH) { break; }
        x += dx;
        y += dy;
        d += RAY_STEP;
    }
    return d;
}

#define DEPTH_COLORS " .,:-+*#&@"
#define DEPTH_COLOR_C 10

int main(void) {
    term_init();
    double player_x = WORLD_WIDTH / 2;
    double player_y = WORLD_HEIGHT / 2;
    double player_a = 0.0;
    for(;;) {
        int c = getchar();
        switch(c) {
            case 'a': 
                player_a += TAU / 12.0; // 30 degrees counter-clockwise
                break;
            case 'd': 
                player_a -= TAU / 12.0; // 30 degrees clockwise
                break;
            case 'w': {
                double d = cast_ray(player_x, player_y, player_a);
                d -= MIN_WALL_DIST;
                if(d < 0.0) { d = 0.0; }
                if(d > 1.0) { d = 1.0; }
                player_x += cos(player_a) * d;
                player_y += sin(player_a) * d;
                break;
            }
            case 's': {
                double d = cast_ray(player_x, player_y, player_a + TAU / 2.0);
                d -= MIN_WALL_DIST;
                if(d < 0.0) { d = 0.0; }
                if(d > 1.0) { d = 1.0; }
                player_x -= cos(player_a) * d;
                player_y -= sin(player_a) * d;
                break;
            }
        }
        unsigned int columns, rows;
        get_term_size(&columns, &rows);
        columns -= 1; // for new lines
        double ray_depths[columns];
        double ray_base_a = player_a + FOV / 2.0;
        for(unsigned int column = 0; column < columns; column += 1) {
            double ray_a = ray_base_a
                - (double) column / (double) columns * FOV;
            ray_depths[column] = cast_ray(player_x, player_y, ray_a);
        }
        term_reset();
        for(unsigned int row = 0; row < rows - 1; row += 1) {
            for(unsigned int column = 0; column < columns; column += 1) {
                double depth = ray_depths[column];
                if(depth < 1.0) { depth = 1.0; }
                int wall_h = (int) ((double) rows / depth);
                int wall_rs = (rows - wall_h) / 2;
                if(row < wall_rs || row > wall_rs + wall_h) {
                    putchar(' ');
                    continue;
                }
                int c_idx = (int) ((1.0 - depth / MAX_RAY_DEPTH) * DEPTH_COLOR_C);
                if(c_idx < 0) { c_idx = 0; }
                if(c_idx >= DEPTH_COLOR_C) { c_idx = DEPTH_COLOR_C - 1; }
                char c = DEPTH_COLORS[c_idx];
                putchar(c);
            }
            putchar('\n');
        }
        printf("x: %f\ty: %f\tangle: %f", player_x, player_y, player_a / TAU * 360.0);
        fflush(stdout);
    }
    return 0;
}