"""Colorize a large cloud of 1M points by passing
colors and transparencies in the format (R,G,B,A)
"""
from vedo import *
import numpy as np
import time

settings.renderPointsAsSpheres = False
settings.pointSmoothing = False
settings.xtitle = 'red axis'
settings.ytitle = 'green axis'
settings.ztitle = 'blue*alpha axis'

N = 1000000

pts = np.random.rand(N, 3)
RGB = pts * 255
Alpha = pts[:, 2] * 255
RGBA = np.c_[RGB, Alpha]  # concatenate

print("clock starts")
t0 = time.time()

# passing c in format (R,G,B,A) is ~50x faster
pts = Points(pts, r=2, c=RGBA) #fast
#pts = Points(pts, r=2, c=pts, alpha=pts[:, 2]) #slow

t1 = time.time()
print("-> elapsed time:", t1-t0, "seconds for N:", N)

show(pts, __doc__, axes=True)