Pixel visual¶
Show the pixel visual.
Tags: pixel, panzoom
Extra Python dependencies: matplotlib
import matplotlib.colors as mcolors
import numpy as np
import datoviz as dvz
def generate_data():
"""Return N, positions (N,3) float32, colors (N,4) uint8"""
# Parameters
n_arms = 5
n_particles_per_arm = 200_000
n_total = n_arms * n_particles_per_arm
rng = np.random.default_rng(seed=3141)
# Radius from center, with more points toward center
r = rng.power(2.0, size=n_total) # values in [0, 1), biased toward 0
# Angle with swirl per arm and some noise
base_theta = np.repeat(np.linspace(0, 2 * np.pi, n_arms, endpoint=False), n_particles_per_arm)
swirl = r * 3 # spiral effect
noise = rng.normal(scale=0.2, size=n_total)
theta = base_theta + swirl + noise
# Convert polar to Cartesian
x = r * np.cos(theta) * 6.0 / 8.0 # HACK: window aspect ratio
y = r * np.sin(theta)
z = np.zeros_like(x)
positions = np.stack([x, y, z], axis=1).astype(np.float32)
# Colors based on radius and angle — create a vibrant, cosmic feel
hue = (theta % (2 * np.pi)) / (2 * np.pi) # hue from angle
saturation = np.clip(r * 1.5, 0.2, 1.0) # more saturated at edges
value = np.ones_like(hue)
# Convert HSV to RGB
rgb = mcolors.hsv_to_rgb(np.stack([hue, saturation, value], axis=1))
rgb_u8 = (rgb * 255).astype(np.uint8)
# Alpha: slight fade with radius
alpha = np.clip(128 * (1.0 - r), 1, 255).astype(np.uint8)
alpha = (200 * np.exp(-5 * r * r)).astype(np.uint8)
colors = np.concatenate([rgb_u8, alpha[:, None]], axis=1)
return n_total, positions, colors
N, position, color = generate_data()
app = dvz.App()
figure = app.figure()
panel = figure.panel()
panzoom = panel.panzoom()
visual = app.pixel(position=position, color=color)
panel.add(visual)
app.run()
app.destroy()