python - pyxel 制作游戏

之前看了一个项目，觉得还挺有意思的，是关于做一个像素风的游戏，现在，虚幻4，u3d，已经让游戏愈发的好看，好玩，曾经我们童年的像素风游戏，愈来愈少。所以，这里我们就回味下。

Pyxel是一个python的经典像素风游戏制作引擎。

由于像素风游戏的机制非常简单（如：最多只能显示16种颜色、播放4种声音等），现在你也可以轻松地享受这种游戏的制作过程。

Windows

安装Python3(3.7或更高版本)之后，输入以下pip命令来安装Pyxel：

pip install -U pyxel

在python代码导入Pyxel模块后，首先用init函数指定窗口大小，然后用run函数启动Pyxel应用。

import pyxel

pyxel.init(160, 120)

def update():
    if pyxel.btnp(pyxel.KEY_Q):
        pyxel.quit()

def draw():
    pyxel.cls(0)
    pyxel.rect(10, 10, 20, 20, 11)

pyxel.run(update, draw)

run函数的两个参数update函数和draw函数分别用来在需要时更新帧和绘制画面。

实际应用中，建议将pyxel代码封装成如下类：

import pyxel

class App:
    def __init__(self):
        pyxel.init(160, 120)
        self.x = 0
        pyxel.run(self.update, self.draw)

    def update(self):
        self.x = (self.x + 1) % pyxel.width

    def draw(self):
        pyxel.cls(0)
        pyxel.rect(self.x, 0, 8, 8, 9)

App()

有时也可简单使用show和flip画出简单的画面和动画。

show函数可以显示画面直到ESC键按下。

import pyxel

pyxel.init(120, 120)
pyxel.cls(1)
pyxel.circb(60, 60, 40, 7)
pyxel.show()

#flip函数可以更新一次画面。

import pyxel

pyxel.init(120, 80)

while True:
    pyxel.cls(3)
    pyxel.rectb(pyxel.frame_count % 160 - 40, 20, 40, 40, 7)
    pyxel.flip()

像素风的游戏比较容易制作，关键的逻辑还需要程序员自己去发掘。

下面是一个例子：

from random import randint

import pyxel
import gzip

class App:
    def __init__(self):
        pyxel.init(160, 120, caption="Pyxel Jump")

        #pyxel.load("jump_game.pyxres")

        self.score = 0
        self.player_x = 72
        self.player_y = -16
        self.player_vy = 0
        self.player_is_alive = True

        self.far_cloud = [(-10, 75), (40, 65), (90, 60)]
        self.near_cloud = [(10, 25), (70, 35), (120, 15)]
        self.floor = [(i * 60, randint(8, 104), True) for i in range(4)]
        self.fruit = [(i * 60, randint(0, 104), randint(0, 2), True) for i in range(4)]

        pyxel.playm(0, loop=True)

        pyxel.run(self.update, self.draw)

    def update(self):
        if pyxel.btnp(pyxel.KEY_Q):
            pyxel.quit()

        self.update_player()

        for i, v in enumerate(self.floor):
            self.floor[i] = self.update_floor(*v)

        for i, v in enumerate(self.fruit):
            self.fruit[i] = self.update_fruit(*v)

    def update_player(self):
        if pyxel.btn(pyxel.KEY_LEFT) or pyxel.btn(pyxel.GAMEPAD_1_LEFT):
            self.player_x = max(self.player_x - 2, 0)

        if pyxel.btn(pyxel.KEY_RIGHT) or pyxel.btn(pyxel.GAMEPAD_1_RIGHT):
            self.player_x = min(self.player_x + 2, pyxel.width - 16)

        self.player_y += self.player_vy
        self.player_vy = min(self.player_vy + 1, 8)

        if self.player_y > pyxel.height:
            if self.player_is_alive:
                self.player_is_alive = False
                pyxel.play(3, 5)

            if self.player_y > 600:
                self.score = 0
                self.player_x = 72
                self.player_y = -16
                self.player_vy = 0
                self.player_is_alive = True

    def update_floor(self, x, y, is_active):
        if is_active:
            if (
                self.player_x + 16 >= x
                and self.player_x <= x + 40
                and self.player_y + 16 >= y
                and self.player_y <= y + 8
                and self.player_vy > 0
            ):
                is_active = False
                self.score += 10
                self.player_vy = -12
                pyxel.play(3, 3)
        else:
            y += 6

        x -= 4

        if x < -40:
            x += 240
            y = randint(8, 104)
            is_active = True

        return x, y, is_active

    def update_fruit(self, x, y, kind, is_active):
        if is_active and abs(x - self.player_x) < 12 and abs(y - self.player_y) < 12:
            is_active = False
            self.score += (kind + 1) * 100
            self.player_vy = min(self.player_vy, -8)
            pyxel.play(3, 4)

        x -= 2

        if x < -40:
            x += 240
            y = randint(0, 104)
            kind = randint(0, 2)
            is_active = True

        return (x, y, kind, is_active)

    def draw(self):
        pyxel.cls(12)

        # draw sky
        pyxel.blt(0, 88, 0, 0, 88, 160, 32)

        # draw mountain
        pyxel.blt(0, 88, 0, 0, 64, 160, 24, 12)

        # draw forest
        offset = pyxel.frame_count % 160
        for i in range(2):
            pyxel.blt(i * 160 - offset, 104, 0, 0, 48, 160, 16, 12)

        # draw clouds
        offset = (pyxel.frame_count // 16) % 160
        for i in range(2):
            for x, y in self.far_cloud:
                pyxel.blt(x + i * 160 - offset, y, 0, 64, 32, 32, 8, 12)

        offset = (pyxel.frame_count // 8) % 160
        for i in range(2):
            for x, y in self.near_cloud:
                pyxel.blt(x + i * 160 - offset, y, 0, 0, 32, 56, 8, 12)

        # draw floors
        for x, y, is_active in self.floor:
            pyxel.blt(x, y, 0, 0, 16, 40, 8, 12)

        # draw fruits
        for x, y, kind, is_active in self.fruit:
            if is_active:
                pyxel.blt(x, y, 0, 32 + kind * 16, 0, 16, 16, 12)

        # draw player
        pyxel.blt(
            self.player_x,
            self.player_y,
            0,
            16 if self.player_vy > 0 else 0,
            0,
            16,
            16,
            12,
        )

        # draw score
        s = "SCORE {:>4}".format(self.score)
        pyxel.text(5, 4, s, 1)
        pyxel.text(4, 4, s, 7)

App()

还比较好玩，大家可以尝试下。