trefoil tube surface w/ PlotOptiX

# -*- coding: utf-8 -*-
"""
Created on Mon May 30 00:07:10 2022
"""
import numpy as np
from numpy import cos
from numpy import sin
from numpy import sqrt

# docs, examples: https://plotoptix.rnd.team
from plotoptix import TkOptiX
from plotoptix.utils import make_color
from plotoptix.materials import m_plastic

def trefoil(u, v, r):
    q = 8.0 * cos(3*u) + 17.0
    p = 6.0 * cos(3*u)
    qq = q**2
    pp = p**2
    dc = r * cos(v)
    ds = r * sin(v)
    L = sqrt(q*pp+qq)
    Xuv = sin(u) + 2.0*sin(2*u) -  ( (4.0*sin(2*u)-sin(u))/sqrt(q) ) * dc +\
        ( (p * (4.0*cos(2*u) + cos(u)) ) / L ) * ds
    Yuv = cos(u) - 2.0*cos(2*u) +  ( (cos(u)+4.0*cos(2*u))/sqrt(q) ) * dc -\
        ( (p * (sin(u) - 4.0*sin(2*u)) ) / L ) * ds
    Zuv = (q/L) * ds  - 2.0*sin(3*u)
    return np.array([Xuv, Yuv, Zuv], dtype=np.float32)

r = (0.0, 2.0*np.pi)
n = 500

i = np.linspace(r[0], r[1], n)

U, V = np.meshgrid(i, i)
S = np.swapaxes(trefoil(U, V, 3.0/4.0), 0, 2)

rt = TkOptiX(width=800, height=600)

rt.set_param(min_accumulation_step=2,
             max_accumulation_frames=2000,
             light_shading="Hard")
rt.set_uint("path_seg_range", 6, 15)

rt.setup_material("plastic", m_plastic)

exposure = 0.8; gamma = 2.2
rt.set_float("tonemap_exposure", exposure)
rt.set_float("tonemap_gamma", gamma)
rt.add_postproc("Gamma")

rt.set_background(0)
rt.set_ambient(0.15)

rt.set_surface("surface", S, c=0.94, make_normals=True, mat="plastic")

rt.set_data("plane", geom="Parallelograms",
            pos=[[-10, -5, -16]], u=[200, 0, 0], v=[0, 0, 200],
            c=make_color([0.1, 0.2, 0.3], exposure=exposure, gamma=gamma))

rt.setup_camera("cam1", cam_type="DoF",
                eye=[0, 10, 10], target=[0, 0, 0], up=[0, 1, 0],
                aperture_radius=0.3, aperture_fract=0.2,
                focal_scale=0.99, fov=35)

rt.setup_light("light1", pos=[-15, 20, 15], color=8, radius=6)

rt.start()