island-ctory/src/collision.c

#include "game.h"
#include "map.h"
#include "player.h"

typedef enum {
    COLLF_WALK = (1 << 0),
    COLLF_LADDER = (1 << 1),
    COLLF_PORTAL = (1 << 2),
} coll_state_t;

uint8_t can_move_to(uint8_t x, uint8_t y) {
    const uint8_t coll =
        ((uint8_t*)MAP.collision_ptr)[y * (MAP.map_width + 1) + x];
    return coll & COLLF_WALK;
}

uint8_t get_tile_coord(uint8_t pixel_coord) {
    uint8_t offset = 0;
    if (pixel_coord & 0x7) {
        offset = 8;
    }
    return (pixel_coord + offset) >> 3;
}

uint8_t player_bg_collides(void) {
    const int8_t map_x = PLAYER.x / 8 + MAP.camera_x;
    if (map_x < 0 || map_x + 1 >= MAP.map_width) {
        return 1;
    }

    const int8_t map_y = PLAYER.y_hi / 8 + MAP.camera_y;
    if (map_y < 0 || map_y + 1 >= MAP.map_height) {
        return 1;
    }

    return !(can_move_to(map_x, map_y) && can_move_to(map_x + 1, map_y) &&
             can_move_to(map_x, map_y + 1) &&
             can_move_to(map_x + 1, map_y + 1));
}

uint8_t player_in_air(void) {
    const int8_t x = get_tile_coord(PLAYER.x) + MAP.camera_x;
    if (x < 0 || x + 1 >= MAP.map_width) {
        return 0;
    }

    const int8_t y = get_tile_coord(PLAYER.y_hi) + MAP.camera_y;
    if (y < 0 || y + 2 >= MAP.map_height) {
        return 0;
    }

    return can_move_to(x, y + 2) && can_move_to(x + 1, y + 2);
}