Applying Textures

Plot a mesh with an image projected onto it as a texture.

import pyvista as pv
from pyvista import examples
import numpy as np
from matplotlib.cm import get_cmap

Texture mapping is easily implemented using PyVista. Many of the geometric objects come preloaded with texture coordinates, so quickly creating a surface and displaying an image is simply:

# load a sample texture
tex = examples.download_masonry_texture()

# create a surface to host this texture
surf = pv.Cylinder()

surf.plot(texture=tex)
../../_images/sphx_glr_texture_001.png

But what if your dataset doesn’t have texture coordinates? Then you can harness the pyvista.DataSetFilters.texture_map_to_plane() filter to properly map an image to a dataset’s surface. For example, let’s map that same image of bricks to a curvey surface:

# create a structured surface
x = np.arange(-10, 10, 0.25)
y = np.arange(-10, 10, 0.25)
x, y = np.meshgrid(x, y)
r = np.sqrt(x ** 2 + y ** 2)
z = np.sin(r)
curvsurf = pv.StructuredGrid(x, y, z)

# Map the curved surface to a plane - use best fitting plane
curvsurf.texture_map_to_plane(inplace=True)

curvsurf.plot(texture=tex)
../../_images/sphx_glr_texture_002.png

Note that this process can be completed with any image texture!

# use the puppy image
tex = examples.download_puppy_texture()
curvsurf.plot(texture=tex)
../../_images/sphx_glr_texture_003.png

Textures from Files

What about loading your own texture from an image? This is often most easily done using the pyvista.read_texture() function - simply pass an image file’s path, and this function with handle making a vtkTexture for you to use.

image_file = examples.mapfile
tex = pv.read_texture(image_file)
curvsurf.plot(texture=tex)
../../_images/sphx_glr_texture_004.png

NumPy Arrays as Textures

Want to use a programmatically built image? pyvista.UniformGrid objects can be converted to textures using pyvista.image_to_texture() and 3D NumPy (X by Y by RGB) arrays can be converted to textures using pyvista.numpy_to_texture().

# create an image using numpy,
xx, yy = np.meshgrid(np.linspace(-200, 200, 20), np.linspace(-200, 200, 20))
A, b = 500, 100
zz = A * np.exp(-0.5 * ((xx / b) ** 2.0 + (yy / b) ** 2.0))

# Creating a custom RGB image
cmap = get_cmap("nipy_spectral")
norm = lambda x: (x - np.nanmin(x)) / (np.nanmax(x) - np.nanmin(x))
hue = norm(zz.ravel())
colors = (cmap(hue)[:, 0:3] * 255.0).astype(np.uint8)
image = colors.reshape((xx.shape[0], xx.shape[1], 3), order="F")

# Convert 3D numpy array to texture
tex = pv.numpy_to_texture(image)

# Render it!
curvsurf.plot(texture=tex)
../../_images/sphx_glr_texture_005.png

Repeating Textures

What if you have a single texture that you’d like to repeat across a mesh? Simply define the texture coordinates for all nodes explicitly.

Here we create the texture coordinates to fill up the grid with several mappings of a single texture. In order to do this we must define texture coordinates outside of the typical (0, 1) range:

axial_num_puppies = 4
xc = np.linspace(0, axial_num_puppies, curvsurf.dimensions[0])
yc = np.linspace(0, axial_num_puppies, curvsurf.dimensions[1])

xxc, yyc = np.meshgrid(xc, yc)
puppy_coords = np.c_[yyc.ravel(), xxc.ravel()]

By defining texture coordinates that range (0, 4) on each axis, we will produce 4 repetitions of the same texture on this mesh.

Then we must associate those texture coordinates with the mesh through the pyvista.Common.t_coords property.

curvsurf.t_coords = puppy_coords

Now display all the puppies!

# use the puppy image
tex = examples.download_puppy_texture()
curvsurf.plot(texture=tex, cpos="yx")
../../_images/sphx_glr_texture_006.png

Total running time of the script: ( 0 minutes 12.188 seconds)

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