91 lines
2.0 KiB
Python
91 lines
2.0 KiB
Python
|
#!python
|
||
|
|
|
||
|
|
import numpy as np
|
||
|
|
import sys
|
||
|
|
|
||
|
|
# Make up test cases with polygonal luminaires.
|
||
|
|
|
||
|
|
# Step 1: generate a random triangle that lies in the +y half-space.
|
||
|
|
# Make sure it faces the origin.
|
||
|
|
v = np.transpose(np.random.rand(3,3) - [[0.5], [0], [0.5]])
|
||
|
|
normal = np.cross(v[1] - v[0], v[2] - v[0])
|
||
|
|
if (np.dot(normal, v[0]) > 0):
|
||
|
|
v = np.flipud(v)
|
||
|
|
|
||
|
|
# Step 2: compute the irradiance using Lambert's formula.
|
||
|
|
# See Arvo's thesis, equations 3.1 to 3.3.
|
||
|
|
|
||
|
|
def norm(x):
|
||
|
|
return np.sqrt(np.dot(x,x))
|
||
|
|
|
||
|
|
Phi = 0 # vector irradiance
|
||
|
|
for k0 in range(3):
|
||
|
|
k1 = (k0 + 1) % 3
|
||
|
|
Theta = np.arccos(np.dot(v[k0], v[k1]) / (norm(v[k0]) * norm(v[k1])))
|
||
|
|
Gamma1 = np.cross(v[k0], v[k1])
|
||
|
|
Gamma = Gamma1 / norm(Gamma1)
|
||
|
|
Phi += 1 / 4.0 * Theta * Gamma
|
||
|
|
|
||
|
|
irradiance = -np.dot(Phi, [0,1,0])
|
||
|
|
|
||
|
|
# Step 3: write out a nori test scene, wrapped in a t-test
|
||
|
|
|
||
|
|
xml_text = """<?xml version="1.0" encoding="utf-8"?>
|
||
|
|
|
||
|
|
<test type="ttest">
|
||
|
|
<string name="references" value="%g"/>
|
||
|
|
|
||
|
|
<scene>
|
||
|
|
<integrator type="path"/>
|
||
|
|
|
||
|
|
<camera type="perspective">
|
||
|
|
<transform name="toWorld">
|
||
|
|
<lookat origin="0, 0.01, 0"
|
||
|
|
target="0, 0, 0"
|
||
|
|
up="0, 0, 1"/>
|
||
|
|
</transform>
|
||
|
|
<float name="fov" value="1e-6"/>
|
||
|
|
<integer name="width" value="1"/>
|
||
|
|
<integer name="height" value="1"/>
|
||
|
|
</camera>
|
||
|
|
|
||
|
|
<mesh type="obj">
|
||
|
|
<string name="filename" value="floor.obj"/>
|
||
|
|
<bsdf type="diffuse">
|
||
|
|
<color name="albedo" value="0.5, 0.5, 0.5"/>
|
||
|
|
</bsdf>
|
||
|
|
</mesh>
|
||
|
|
|
||
|
|
<mesh type="obj">
|
||
|
|
<string name="filename" value="%s"/>
|
||
|
|
<bsdf type="diffuse">
|
||
|
|
<color name="albedo" value="0, 0, 0"/>
|
||
|
|
</bsdf>
|
||
|
|
<luminaire type="area">
|
||
|
|
<color name="radiance" value="1, 1, 1"/>
|
||
|
|
</luminaire>
|
||
|
|
</mesh>
|
||
|
|
</scene>
|
||
|
|
</test>
|
||
|
|
"""
|
||
|
|
|
||
|
|
obj_text = """v %g %g %g
|
||
|
|
v %g %g %g
|
||
|
|
v %g %g %g
|
||
|
|
f 1 2 3
|
||
|
|
"""
|
||
|
|
|
||
|
|
if len(sys.argv) < 3:
|
||
|
|
print "Usage: python polylum.py <xml output file> <obj output file>"
|
||
|
|
sys.exit(-1)
|
||
|
|
|
||
|
|
fname_obj = sys.argv[2]
|
||
|
|
|
||
|
|
f_xml = open(sys.argv[1], 'w')
|
||
|
|
f_xml.write(xml_text % (.5 / np.pi * irradiance, fname_obj))
|
||
|
|
f_xml.close()
|
||
|
|
|
||
|
|
f_obj = open(fname_obj, 'w')
|
||
|
|
f_obj.write(obj_text % tuple(v.flat))
|
||
|
|
f_obj.close()
|