GBA的3D引擎源码

IWRAM_CODE int main() {
    const int vidmode = MODE_4 | BG2_ON;
    REG_DISPCNT = vidmode;

    *(BG_PALETTE   1) = RGB5(31, 5, 5);
    *(BG_PALETTE   2) = RGB8(0x9b, 0xad, 0xb7);
    *(BG_PALETTE   3) = RGB8(0x84, 0x7e, 0x87);

    init_palette();
    
    int x, y;
    int frames = 0;
    int prev_input = 0;

    init_blockmap();

    INT_VECTOR = (IntFn) interrupt;
    REG_DISPSTAT |= LCDC_VBL;
    REG_IE |= IRQ_VBLANK;
    REG_IME = 1;

    block_traversal_limit = render_dists[render_dist_i];

    while (1) {
        while(REG_VCOUNT != 0);
        frames = frame_counter;
        frame_counter = 0;

        REG_DISPCNT = vidmode | (display_frame ? BIT(4) : 0);
        vid_addr = (u16*) (0x06000000   (display_frame ? 0 : 0xA000));

        input = ~REG_KEYINPUT;
        input_delta = prev_input ^ input;
        prev_input = input;

        if (input & input_delta & KEY_SELECT) {
            freeze_traversal ^= 1;
        }
        if (input & input_delta & KEY_L) {
            if (  render_dist_i == (sizeof(render_dists) / sizeof(int)))
                render_dist_i = 0;
            
            block_traversal_limit = render_dists[render_dist_i];
        }

        // cam_x_sin = fastsin(cam_rot.x);
        // cam_x_cos = fastcos(cam_rot.x);

        // cam_y_sin = fastsin(cam_rot.y);
        // cam_y_cos = fastcos(cam_rot.y);

        player_update();

        //clear_screen();
        fast_clear(vid_addr);
        //profile(3);
        traverse_blocks();
        //profile(4);
        draw_blocks();
        //profile(5);
        
        if (freeze_traversal)
            plot_pixel(vid_addr   120 * 16, 1);

        draw_crosshair();

        for (int i = 0; i < frames; i  ) {
            *(vid_addr   120 * 8   4   i * 2) = 0x0101;
            *(vid_addr   120 * 9   4   i * 2) = 0x0101;
        }

        display_frame ^= 1;
    }
}