How to build a quarter cylinder using python script?

Question

I am a new Blender user and couldn't find the API for adding a quarter-cylinder object. And I also want to build the object like the picture shows. Thanks if you can help!

Answer 1

I'm not sure exactly what shape you want to make.

This will create an annular sector of a cylinder.

import bpy
import math


def create_cylinder_sector(
    height,
    angle_start,
    angle_end,
    inner_radius,
    outer_radius,
    inner_segments,
    outer_segments,
):
    angle_diff = angle_end - angle_start
    inner_angle_step = angle_diff / inner_segments
    outer_angle_step = angle_diff / outer_segments

    verts, faces = [], []

    # Verts: Inner arc
    if inner_radius > 0:
        for i in range(inner_segments + 1):
            angle = angle_start + inner_angle_step * i
            x = inner_radius * math.cos(angle)
            y = inner_radius * math.sin(angle)
            verts.append((x, y, 0))
            verts.append((x, y, height))
    else:
        verts.append((0, 0, 0))
        verts.append((0, 0, height))

    # Verts: Outer arc
    for i in range(outer_segments + 1):
        angle = angle_end - outer_angle_step * i
        x = outer_radius * math.cos(angle)
        y = outer_radius * math.sin(angle)
        verts.append((x, y, 0))
        verts.append((x, y, height))

    # Faces: Three sides
    for i in range(0, len(verts), 2):
        faces.append((i, i+1, i+3, i+2))
    # Faces: Fourth side
    faces.append((len(verts) - 2, len(verts) - 1, 1, 0)) 
    # Faces: Bottom
    faces.append([i for i in range(0, len(verts), 2)])
    # Faces: Top
    faces.append([i for i in range(len(verts) - 1, 0, -2)])

    mesh = bpy.data.meshes.new("CylinderSector")
    mesh.from_pydata(verts, [], faces)
    mesh.validate()

    ob = bpy.data.objects.new(mesh.name, mesh)
    bpy.context.scene.collection.objects.link(ob)

    return ob


# Example
create_cylinder_sector(
    height=1,
    angle_start=0.4,
    angle_end=1.8,
    inner_radius=0.5,
    outer_radius=1.5,
    inner_segments=3,
    outer_segments=6,
)

If you want a quarter like this, you can pass inner_radius=0:

create_cylinder_sector(
    height=1,
    angle_start=0,
    angle_end=math.pi/2,
    inner_radius=0,
    outer_radius=1.5,
    inner_segments=3,  # ignored when inner_radius=0
    outer_segments=9,
)

Answer 2

To build a quarter cylinder using a Python script, you can follow these steps:

1. Import the required modules:

import matplotlib.pyplot as plt
import numpy as np
from mpl_toolkits.mplot3d import Axes3D

2. Define the radius of the cylinder:

r = 1

3. Define the height of the cylinder:

h = 1

4. Define the number of points to be used for the plot:

n = 100

5. Generate the x, y, and z coordinates for the plot using numpy:

theta = np.linspace(0, np.pi/2, n)
x = r * np.cos(theta)
y = r * np.sin(theta)
z = np.linspace(0, h, n)

6. Create a 3D plot using the generated coordinates:

fig = plt.figure()
ax = fig.add_subplot(111, projection='3d')
ax.plot(x, y, z)
plt.show()

This will generate a quarter-cylinder plot with the specified radius and height. You can adjust the values of r, h, and n to change the dimensions and resolution of the plot.