如何在 Python 中进行游标锁定？

Question

我正在 Python 中使用 Turtle 制作“3D”立方体。我正在尝试找到一种方法，以便我可以锁定光标，或者当您按住右键单击时，您可以从不同角度查看立方体。由于我不会这样做，所以我有一个旋转功能。

我当前的代码：

import turtle

VERTEXES = [(-1, -1, -1), ( 1, -1, -1), ( 1,  1, -1), (-1,  1, -1),
            (-1, -1,  1), ( 1, -1,  1), ( 1,  1,  1), (-1,  1,  1)]

TRIANGLES = [
    (0, 1, 2), (2, 3, 0),
    (0, 4, 5), (5, 1, 0),
    (0, 4, 3), (4, 7, 3),
    (5, 4, 7), (7, 6, 5),
    (7, 6, 3), (6, 2, 3),
    (5, 1, 2), (2, 6, 5)
]

FOV = 400

# Create turtle,
pointer = turtle.Turtle()

# Turn off move time, makes drawing instant,
turtle.tracer(0, 0)
pointer.up()

def rotate(x, y, r):
  s, c = sin(r), cos(r)
  return x * c - y * s, x * s + y * c

counter = 0
while True:
    # Clear screen,
    pointer.clear()

    # Draw,
    for triangle in TRIANGLES:
        points = []
        for vertex in triangle:
            # Get the X, Y, Z coords out of the vertex iterator,
            x, y, z = VERTEXES[vertex]

            # Rotate,
            x, z = rotate(x, z, counter)
            y, z = rotate(y, z, counter)
            x, y = rotate(x, y, counter)

            # Perspective formula,
            z += 5
            f = FOV / z
            sx, sy = x * f, y * f

            # Add point,
            points.append((sx, sy))
        
        # Draw triangle,
        pointer.goto(points[0][0], points[0][1])
        pointer.down()

        pointer.goto(points[1][0], points[1][1])
        pointer.goto(points[2][0], points[2][1])
        pointer.goto(points[0][0], points[0][1])
        pointer.up()

    # Update,
    turtle.update()

    counter += 0.01

Answer 1

首先，我只想说 Turtle 对鼠标事件和其他框架所具有的其他有趣功能的支持不多。

由于海龟在通过屏幕事件触发时不支持鼠标弹起事件，这将允许您右键单击而不是按住它，并且它将在设置鼠标之前继续获取鼠标移动的增量回到原来的位置。完成拖动鼠标后，再次单击鼠标右键即可松开鼠标。

增量会很低，通常在 1-3 之间。如果这太低，则添加 time.sleep(1/60)。这会将 fps 锁定为 60 帧，并允许鼠标在锁定回其原始位置之前移动更多。

我也想炫耀这个问题，因为它似乎有一种方法可以添加鼠标弹起并将事件移动到乌龟，但我会让你看看它来决定你是否想走那条路。

找到光标在Python海龟中的当前位置

祝你好运。

from ctypes import windll, Structure, c_long, byref
from turtle import Turtle, Screen, update


is_dragging = False
start_mouse_pos = (0, 0)


class POINT(Structure):
    _fields_ = [("x", c_long), ("y", c_long)]
    x: int
    y: int


def getMousePosition():
    pt = POINT()
    windll.user32.GetCursorPos(byref(pt))
    return (pt.x, pt.y)


def setMousePosition(pos: tuple):
    windll.user32.SetCursorPos(int(pos[0]), int(pos[1]))


def onScreenClick(x, y):
    global is_dragging, start_mouse_pos
    is_dragging = not is_dragging
    start_mouse_pos = getMousePosition()


turtle = Turtle()
screen = Screen()
screen.onscreenclick(onScreenClick, 3)

while True:
    if is_dragging:
        pos = getMousePosition()
        delta_pos = (start_mouse_pos[0] - pos[0], start_mouse_pos[1] - pos[1])

        # Do something with how much the mouse has moved then set the mouse position back

        setMousePosition(start_mouse_pos)
    update()

Answer 2

您应该可以使用 ondrag() 事件处理程序来执行此操作。下面是对代码的修改，以删除自动移动并通过单击红色角并在继续按住按钮（拖动）的同时移动鼠标来替代手动移动立方体的能力：

from math import sin, cos, atan2 as atan
from turtle import Screen, Turtle

VERTEXES = [
    (-1, -1, -1), (1, -1, -1), (1, 1, -1), (-1, 1, -1),
    (-1, -1, 1), (1, -1, 1), (1, 1, 1), (-1, 1, 1)
]

TRIANGLES = [
    (0, 1, 2),
    (2, 3, 0),
    (0, 4, 5),
    (5, 1, 0),
    (0, 4, 3),
    (4, 7, 3),
    (5, 4, 7),
    (7, 6, 5),
    (7, 6, 3),
    (6, 2, 3),
    (5, 1, 2),
    (2, 6, 5)
]

FOV = 400

def rotate(x, y, r):
    s, c = sin(r), cos(r)

    return x * c - y * s, x * s + y * c

orientation = 0  # radians

def draw():
    global orientation

    turtle.clear()

    for triangle in TRIANGLES:
        for flag, vertex in enumerate(triangle):
            # Get the X, Y, Z coords out of the vertex iterator
            x, y, z = VERTEXES[vertex]

            # Rotate
            x, z = rotate(x, z, orientation)
            y, z = rotate(y, z, orientation)
            x, y = rotate(x, y, orientation)

            # Perspective formula
            z += 5
            f = FOV / z
            s = x * f, y * f

            # Draw line
            turtle.setposition(s)
            turtle.pendown()

            if not flag:
                start = s

        turtle.setposition(start)
        turtle.penup()

    screen.update()

def orient(x, y):
    global orientation

    turtle.ondrag(None)  # disable handler inside handler

    orientation = atan(y, x)
    draw()

    turtle.ondrag(orient)  # reenable handler

# Turn off move time, makes drawing instant,
screen = Screen()
screen.tracer(False)

# Create turtle,
turtle = Turtle('circle')
turtle.fillcolor('red')
turtle.shapesize(0.5)
turtle.penup()

draw()

turtle.ondrag(orient)

screen.mainloop()

鼠标位置到立方体位置的映射显然不是最优的，但应该足以让您相信这是可能的并提供一个起点。

如何在 Python 中进行游标锁定？

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