Gumballs

Spheres rendered as gumballs made from a Monte Carlo simulation with HOOMD.

• Geometry: geometry.Sphere: radius = 0.5

  • material: primitive_color_mix = 1.0, roughness = 0.2, specular = 0.8

  • positions: output of a HOOMD simulation

  • colors: randomly assigned from a set of gumball colors

• Lighting: light.lightbox with an additional light

• Rendered with: tracer.Path: samples = 256, light_samples = 64 on the GPU

Source code

# Copyright (c) 2016-2026 The Regents of the University of Michigan
# Part of fresnel, released under the BSD 3-Clause License.

"""Gumballs example scene."""

import os
import sys

import numpy as np
import PIL
from matplotlib.colors import LinearSegmentedColormap

import fresnel

# First, we create a color map for gumballs.
colors = [
    "#e56d60",
    "#ee9944",
    "#716e80",
    "#eadecd",
    "#cec746",
    "#c0443f",
    "#734d56",
    "#5d5f7b",
    "#ecb642",
    "#8a9441",
]
cmap = LinearSegmentedColormap.from_list(name="gumball", colors=colors, N=len(colors))

rng = np.random.default_rng(123)


# Next, we gather information needed for the geometry.
position = np.load("gumballs.npz")["position"]
color = fresnel.color.linear(cmap(rng.random(len(position))))
material = fresnel.material.Material(
    primitive_color_mix=1.0,
    roughness=0.2,
    specular=0.8,
)

# We create a fresnel scene and its geometry.
scene = fresnel.Scene()

geometry = fresnel.geometry.Sphere(
    scene,
    position=position,
    radius=0.5,
    color=color,
    material=material,
)

# Configure camera and lighting.
scene.camera = fresnel.camera.Perspective(
    position=(0, 0, 25),
    look_at=(0, 0, 0),
    up=(0, 1, 0),
    focal_length=0.5,
    f_stop=0.25,
)
scene.camera.focus_on = (0, 0, 5.6)
scene.lights = fresnel.light.lightbox()
scene.lights.append(
    fresnel.light.Light(direction=(0.3, -0.3, 1), color=(0.5, 0.5, 0.5), theta=np.pi)
)

if "CI" in os.environ:
    samples = 1
else:
    samples = 128

# Execute rendering.
out = fresnel.pathtrace(scene, w=600, h=600, samples=samples, light_samples=64)
PIL.Image.fromarray(out[:], mode="RGBA").save("gumballs.png")

if len(sys.argv) > 1 and sys.argv[1] == "hires":
    out = fresnel.pathtrace(scene, w=1500, h=1500, samples=256, light_samples=64)
    PIL.Image.fromarray(out[:], mode="RGBA").save("gumballs-hires.png")

Author

Bradley Dice