4. Vorlesung

Hong-Phuc Bui

2025-05-05 3d708d0aa935c6352de84a98592991c8638e7181

4. Vorlesung

 03-funktion/Inhalt.md

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# Tupel




# Liste


 04-schleife/README.md

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# Schleife in Python

 

## While Schleife

## For Schleife

## Anwendungen

 04-schleife/canvas-bezier/.gitignore

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.venv/
.idea/
__pycache__/

 04-schleife/canvas-bezier/bezier.py

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""""
Module related to bezier curve
"""
def make_cubic_bezier(control_points: [(float, float)], n: int = 10) -> [(float, float)]:
    """"
    Interpolate a Bezier-curve by split it into segments of lines (=polyline).
    A Bezier-Curve is defined by

        \[
            B(P_0, P_1, P_2, P_3:t) = (1-t)^3*P_0 + 3(1-t)^2*t*P_1 + 3(1-t)*t^2*P_2 + t^3*P_3
        \]

    for $t \in \[0, 1\]$

    :param control_points
    :param n number of segments
    :return a list of points on the Bezier-Curve.
    """

    p0x = control_points[0][0]
    p0y = control_points[0][1]
    p1x = control_points[1][0]
    p1y = control_points[1][1]
    p2x = control_points[2][0]
    p2y = control_points[2][1]
    p3x = control_points[3][0]
    p3y = control_points[3][1]
    points = [(p0x, p0y)]
    for i in range(1, n):
        t = i / n
        u = 1 - t
        x = p0x * u**3 + 3 * p1x * t* u**2 + 3 * p2x * t**2 * u + p3x * t**3
        y = p0y * u**3 + 3 * p1y * t* u**2 + 3 * p2y * t**2 * u + p3y * t**3
        points.append( (x,y) )
    points.append((p3x, p3y))
    return points


def make_svg_polyline(points) -> str:
    line = map(lambda p: f"{p[0]},{p[1]}", points)
    svg = f'<polyline points="{" ".join(line)}" fill="none" stroke="gray" stroke-width="3" />'
    return svg


 04-schleife/canvas-bezier/main-canvas.py

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from tkinter import *

from bezier import make_cubic_bezier

def draw_bezier(canvas, control_points):
    points = make_cubic_bezier(control_points, n= 400)
    for i in range(1,len(points)):
        x1 = points[i-1][0]
        y1 = points[i-1][1]
        x2 = points[i][0]
        y2 = points[i][1]
        canvas.create_line(x1,y1, x2,y2)


def get_point(event):
    global control_points
    point = x, y = (event.x, event.y)
    control_points.append(point)
    canvas.create_oval(x, y, x+3, y+3)
    if len(control_points) == 4:
        draw_bezier(canvas, control_points)
        control_points = []


if __name__ == '__main__':

    control_points = []

    root = Tk()

    canvas = Canvas(root, width=800, height=800)
    canvas.pack()

    canvas.bind('<Button-1>', get_point)

    root.mainloop()

 04-schleife/canvas-bezier/main-nicegui.py

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from nicegui import ui

from bezier import make_cubic_bezier, make_svg_polyline

control_points = []
svg = ""

def get_point(event):
    global control_points
    global svg
    x = event.image_x
    y = event.image_y
    control_points.append((x,y))
    svg += f'<circle cx="{x}" cy="{y}" r="1" fill="orange" />'
    ui.notification(f"(x,y) = ({x},{y})")
    if len(control_points) == 4:
        bezier_points = make_cubic_bezier(control_points, n = 50)
        svg += make_svg_polyline(bezier_points)
        control_points.clear()
    event.sender.set_content(svg)

ui.interactive_image(
    size=(900, 400), cross=True,
    on_mouse=get_point,
).classes('w-full bg-blue-50')

ui.run()


 04-schleife/kleine-ein-mal-eins.py

 canvas-bezier/.idea/canvas-bezier.iml

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