0342-Tetris-解决旋转时碰撞

环境

• Time 2023-08-22
• Zig 0.12.0-dev.161+6a5463951
• WSL-Ubuntu 22.04.3 LTS

前言

说明

参考资料：

1. https://www.youtube.com/watch?v=nF_crEtmpBo
2. https://github.com/howprice/sdl2-tetris

目标

移动时现在都有碰撞检测，但是旋转时没有。在旋转的时候，也需要检测是否碰撞，碰撞时不旋转。

app.zig

...
    pub fn rotate(self: *Game, screen: *Screen) void {
        var temp = self.current;
        self.current.rotate();
        self.current.locateIn();
        if (self.isFit(screen)) {
            self.current = temp;
        }
    }
...

旋转前保存当前的方块状态，旋转后，如果发生了碰撞，则将其还原。

效果

总结

如果旋转后有碰撞，则将其还原，相当于如果有碰撞，则不能进行旋转。

附录

app.zig 源码

const std = @import("std");
const Screen = @import("display.zig").Screen;
const Tetrimino = @import("block.zig").Tetrimino;

pub const Game = struct {
    current: Tetrimino,
    prng: std.rand.DefaultPrng,

    pub fn new() Game {
        const seed = @as(u64, @intCast(std.time.timestamp()));
        var rand = std.rand.DefaultPrng.init(seed);
        return Game{
            .current = Tetrimino.random(&rand),
            .prng = rand,
        };
    }

    pub fn drawCurrent(self: *Game, screen: *Screen) void {
        draw(&self.current, screen);
    }

    pub fn moveLeft(self: *Game, screen: *Screen) void {
        _ = self.move(screen, -1, 0);
    }

    pub fn moveRight(self: *Game, screen: *Screen) void {
        _ = self.move(screen, 1, 0);
    }

    pub fn moveDown(self: *Game, screen: *Screen) void {
        if (self.move(screen, 0, 1)) {
            self.current.solid = true;
            draw(&self.current, screen);
            self.current = Tetrimino.random(&self.prng);
        }
    }

    fn move(self: *Game, screen: *const Screen, x: i8, y: i8) bool {
        self.current.x = self.current.x + x;
        self.current.y = self.current.y + y;
        self.current.locateIn();

        return if (self.isFit(screen)) {
            _ = self.move(screen, -x, -y);
            return true;
        } else false;
    }

    pub fn rotate(self: *Game, screen: *Screen) void {
        var temp = self.current;
        self.current.rotate();
        self.current.locateIn();
        if (self.isFit(screen)) {
            self.current = temp;
        }
    }

    fn isFit(self: *const Game, screen: *const Screen) bool {
        const value = self.current.position();
        var index: usize = 0;
        while (index < value.len) : (index += 2) {
            const col = self.current.y + value[index + 1];
            if (col < 0) return true;
            const row: usize = @intCast(self.current.x + value[index]);
            if (screen.hasSolid(row, @intCast(col))) return true;
        }
        return false;
    }
};

fn draw(block: *const Tetrimino, screen: *Screen) void {
    const value = block.position();
    var index: usize = 0;
    while (index < value.len) : (index += 2) {
        const row: usize = @intCast(block.x + value[index]);
        const col: usize = @intCast(block.y + value[index + 1]);
        if (block.solid) {
            screen.drawSolid(row, col, block.color);
        } else {
            screen.draw(row, col, block.color);
        }
    }
}