How to Draw a Triangle in Python 3D PLot

In this tutorial, you’ll learn various methods to plot 3D triangles in Python.

We’ll explore different libraries to create 3D triangle plots.

 

 

Using plot_trisurf

The plot_trisurf method from Matplotlib is a straightforward way to create triangle 3D plots.

To create a 3D triangle plot using plot_trisurf, you can use the following code:

import numpy as np
import matplotlib.pyplot as plt
vertices = np.array([[0, 0, 0], [1, 0, 0], [0.5, np.sqrt(3)/2, 0]])
fig = plt.figure()
ax = fig.add_subplot(111, projection='3d')
ax.plot_trisurf(vertices[:, 0], vertices[:, 1], vertices[:, 2])
ax.set_xlabel('X')
ax.set_ylabel('Y')
ax.set_zlabel('Z')
ax.set_title('3D Triangle using plot_trisurf')
plt.show()

Output:

The triangle is defined by three vertices in the XY plane, with Z values set to 0.

 

Using the plot_surface with a meshgrid

You can use the plot_surface method to create a triangle in a 3D plot with a meshgrid for more control over the surface appearance.

Here’s how you can create a 3D triangle plot using plot_surface:

import numpy as np
import matplotlib.pyplot as plt
vertices = np.array([[0, 0, 0], [1, 0, 1], [0.5, np.sqrt(3)/2, 0.5]])
x = np.linspace(0, 1, 100)
y = np.linspace(0, np.sqrt(3)/2, 100)
X, Y = np.meshgrid(x, y)

# Define the plane equation
Z = 1 - X - Y/np.sqrt(3)
mask = (Y <= np.sqrt(3) * X) & (Y <= np.sqrt(3) * (1 - X))
Z[~mask] = np.nan
fig = plt.figure()
ax = fig.add_subplot(111, projection='3d')
surf = ax.plot_surface(X, Y, Z, cmap='viridis')
ax.set_xlabel('X')
ax.set_ylabel('Y')
ax.set_zlabel('Z')
ax.set_title('3D Triangle using plot_surface')
fig.colorbar(surf)
plt.show()

Output:

This code defines the triangle vertices, creates a meshgrid, and applies a mask to show only the triangle area.

 

Using Poly3DCollection

To create a triangle 3D plot using Poly3DCollection, you can use this code:

import numpy as np
import matplotlib.pyplot as plt
from mpl_toolkits.mplot3d.art3d import Poly3DCollection
vertices = np.array([[0, 0, 0], [1, 0, 1], [0.5, np.sqrt(3)/2, 0.5]])
fig = plt.figure()
ax = fig.add_subplot(111, projection='3d')

# Create a Poly3DCollection
triangle = Poly3DCollection([vertices], alpha=0.8, edgecolor='k')
triangle.set_facecolor('cyan')
ax.add_collection3d(triangle)
ax.set_xlim(0, 1)
ax.set_ylim(0, 1)
ax.set_zlim(0, 1)
ax.set_xlabel('X')
ax.set_ylabel('Y')
ax.set_zlabel('Z')
ax.set_title('3D Triangle using Poly3DCollection')
plt.show()

Output:

This code defines the triangle vertices and creates a collection with custom face color and edge color.

 

Using Plotly

Here’s how you can create an interactive triangle in 3D plot using Plotly:

import plotly.graph_objects as go
import numpy as np
vertices = np.array([[0, 0, 0], [1, 0, 1], [0.5, np.sqrt(3)/2, 0.5]])
x, y, z = vertices.T
i = [0, 0]
j = [1, 2]
k = [2, 1]

# Create the triangle plot
fig = go.Figure(data=[
    go.Mesh3d(x=x, y=y, z=z, i=i, j=j, k=k, color='cyan', opacity=0.8)
])

# Set layout options
fig.update_layout(
    scene=dict(
        xaxis_title='X',
        yaxis_title='Y',
        zaxis_title='Z'
    ),
    title='Interactive 3D Triangle using Plotly'
)
fig.show()

Output:

This code defines the triangle vertices and creates a mesh using the Mesh3d object.

 

Using VTK

To create a triangle in 3D plot using VTK, you can use the following code:

import vtk
import numpy as np
points = vtk.vtkPoints()
points.InsertNextPoint(0, 0, 0)
points.InsertNextPoint(1, 0, 1)
points.InsertNextPoint(0.5, np.sqrt(3)/2, 0.5)
triangle = vtk.vtkTriangle()
triangle.GetPointIds().SetId(0, 0)
triangle.GetPointIds().SetId(1, 1)
triangle.GetPointIds().SetId(2, 2)
triangles = vtk.vtkCellArray()
triangles.InsertNextCell(triangle)

# Create a polydata object
trianglePolyData = vtk.vtkPolyData()
trianglePolyData.SetPoints(points)
trianglePolyData.SetPolys(triangles)

# Create mapper and actor
mapper = vtk.vtkPolyDataMapper()
mapper.SetInputData(trianglePolyData)

actor = vtk.vtkActor()
actor.SetMapper(mapper)
actor.GetProperty().SetColor(0, 1, 1)

# Create a renderer, render window, and interactor
renderer = vtk.vtkRenderer()
renderWindow = vtk.vtkRenderWindow()
renderWindow.AddRenderer(renderer)
renderWindowInteractor = vtk.vtkRenderWindowInteractor()
renderWindowInteractor.SetRenderWindow(renderWindow)
renderer.AddActor(actor)
renderer.SetBackground(0.1, 0.1, 0.1)  # Dark gray background
renderWindow.Render()
renderWindowInteractor.Start()

Output:

This code defines the triangle vertices, creates a polydata object, and sets up the rendering pipeline.

 

Using Mayavi

You can use the triangular_mesh function to create a triangle in 3D plot using Mayavi:

from mayavi import mlab
import numpy as np
vertices = np.array([[0, 0, 0], [1, 0, 1], [0.5, np.sqrt(3)/2, 0.5]])

# Create the triangle plot
mlab.triangular_mesh([vert[0] for vert in vertices],
                     [vert[1] for vert in vertices],
                     [vert[2] for vert in vertices],
                     [(0, 1, 2)],
                     color=(0, 1, 1))  # Cyan color

mlab.view(azimuth=45, elevation=30, distance=4)
mlab.xlabel('X')
mlab.ylabel('Y')
mlab.zlabel('Z')
mlab.title('3D Triangle using Mayavi')
mlab.show()

Output: