如何在Python Ursina引擎中为角色添加重力效果

你可以基于现有代码做以下几处修改即可实现重力效果，还可额外添加跳跃支持：

• 新增重力、玩家垂直速度、跳跃力度三个全局参数，可根据手感自由调整数值
• 在update函数中每帧更新垂直速度，处理地面碰撞检测，避免玩家穿过方块
• 调整原有左右移动的碰撞判断逻辑，适配非整数y坐标的情况
• 可选在input函数中添加跳跃触发逻辑

from ursina import *
from math import floor


app = Ursina()

size = 32
plane = Entity(model='quad', color=color.azure, origin=(-.5,-.5), z=10, collider='box', scale=size) # create an invisible plane for the mouse to collide with
grid = [[Entity(model='quad', position=(x,y), texture='white_cube', enabled=False) for y in range(size)] for x in range(size)] # make 2d array of entities
player = Entity(model='quad', color=color.orange, position=(16,16,-.1))
cursor = Entity(model=Quad(mode='line'), color=color.lime)

# 新增重力相关参数
gravity = -22  # 重力加速度，数值越大下落越快
player_y_velocity = 0  # 玩家垂直方向速度
jump_force = 8  # 跳跃力度，数值越大跳的越高
on_ground = False  # 标记玩家是否站在地面上

def update():
    global player_y_velocity, on_ground
    if mouse.hovered_entity == plane:
        # round the cursor position
        cursor.position = mouse.world_point
        cursor.x = round(cursor.x, 0)
        cursor.y = round(cursor.y, 0)

    # 重力逻辑处理
    player_y_velocity += gravity * time.dt
    target_y = player.y + player_y_velocity * time.dt
    # 检测脚下是否有方块
    player_grid_x = int(player.x)
    player_bottom_y = target_y - 0.5  # 玩家底部的y坐标，因为quad默认中心为原点，高度为1
    on_ground = False
    if player_bottom_y < size and player_grid_x >=0 and player_grid_x < size:
        if grid[player_grid_x][int(floor(player_bottom_y + 0.001))].enabled:
            # 碰到地面，重置速度，对齐到地面位置
            player_y_velocity = 0
            target_y = int(floor(player_bottom_y)) + 0.5
            on_ground = True
    player.y = target_y

    # 调整后的左右移动逻辑
    if held_keys['a'] and player_grid_x > 0:
        # 判断左侧同高度格子是否阻挡
        if not grid[player_grid_x - 1][int(floor(player.y))].enabled:
            player.x -= 5 * time.dt
    if held_keys['d'] and player_grid_x < size -1:
        # 判断右侧同高度格子是否阻挡
        if not grid[player_grid_x + 1][int(floor(player.y))].enabled:
            player.x += 5 * time.dt


def input(key):
    global player_y_velocity, on_ground
    if key == 'left mouse down':
        grid[int(cursor.x)][int(cursor.y)].enabled = True
    if key == 'right mouse down':
        grid[int(cursor.x)][int(cursor.y)].enabled = False
    # 新增跳跃逻辑，按空格跳跃
    if key == 'space' and on_ground:
        player_y_velocity = jump_force


camera.orthographic = True
camera.fov = 10
camera.position = (16,18)

# enable all tiles lower than 16 to make a ground
for column in grid:
    for e in column:
        if e.y <= 15:
            e.enabled = True

app.run()

如果不需要跳跃功能，直接删掉input函数里的空格判断相关代码即可。

内容的提问来源于stack exchange，提问作者John lennon