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December 7, 2011 07:15
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python ray tracer
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from math import sqrt | |
import pdb | |
DELTA = 1.5e-8 | |
INFINITY = 1e5000 | |
def Vec(x=0.0,y=0.0,z=0.0): | |
return [float(x),float(y),float(z)] | |
def add(a,b): | |
return [a[0]+b[0],a[1]+b[1],a[2]+b[2]] | |
def sub(a,b): | |
return [a[0]-b[0],a[1]-b[1],a[2]-b[2]] | |
def scale(s,a): | |
return [a[0]*s,a[1]*s,a[2]*s] | |
def dot(a,b): | |
return a[0]*b[0] + a[1]*b[1] + a[2]*b[2] | |
def unitize(a): | |
return scale( 1.0 / ( sqrt( dot( a, a) ) ), a) | |
class Ray: | |
def __init__(self, orig, dir ): | |
self.orig = orig | |
self.dir = dir | |
class Hit: | |
def __init__(self, lamb, normal ): | |
self.lamb = float(lamb) | |
self.normal = normal | |
## all objects need to expose | |
## .intersect( hit, ray ) | |
class Sphere: | |
def __init__(self, center, radius): | |
self.center = center | |
self.radius = radius | |
def __str__(self): | |
return "%s,%f" % ( str(self.center), self.radius) | |
def ray_sphere(self, ray): | |
v = sub( self.center, ray.orig) | |
b = dot( v, ray.dir) | |
disc = b*b - dot(v,v) + self.radius*self.radius | |
if disc < 0.0: | |
return INFINITY | |
d = sqrt(disc) | |
t2 = b + d | |
if t2 < 0.0: | |
return INFINITY | |
t1 = b - d | |
if t1 > 0.0: | |
return t1 | |
else: | |
return t2 | |
def intersect(self, hit, ray): | |
l = self.ray_sphere( ray) | |
if l >= hit[0]: | |
return hit | |
n = add( ray.orig, sub( scale( l, ray.dir), self.center)) | |
return [l, unitize( n)] | |
class Group: | |
def __init__(self, sphere): | |
self.bound = sphere | |
self.objs = [] | |
def __str__(self): | |
s = "bound: %s\n" % (self.bound) | |
for t in self.objs: | |
s += "\t" + str(t) + "\n" | |
return s | |
def intersect(self, hit, ray): | |
l = self.bound.ray_sphere( ray) | |
if l >= hit[0]: | |
return hit | |
for s in self.objs: | |
hit = s.intersect( hit, ray) | |
return hit | |
def ray_trace( light, ray, scene): | |
_ = (INFINITY, Vec( 0,0,0)) | |
hit = scene.intersect( _, ray) | |
if hit[0] == INFINITY: | |
return 0.0 | |
o = add( ray.orig, add( scale( hit[0] , ray.dir), scale( DELTA, hit[1]) ) ) | |
g = dot( hit[1], light) | |
if g >= 0.0: | |
return 0.0 | |
sray = Ray( o, scale( -1, light)) | |
si = scene.intersect( (INFINITY, Vec( 0,0,0)), sray) | |
if si[0] == INFINITY: | |
return -g | |
else: | |
return 0.0 | |
def create( level, c, r): | |
sphere = Sphere( c, r) | |
if level == 1: | |
return sphere | |
group = Group( Sphere( c, 3*r)) | |
group.objs.append(sphere) | |
rn = 3*r/sqrt(12) | |
for dz in range(-1,2,2): | |
for dx in range(-1,2,2): | |
c2 = Vec(c[0]+dx*rn, c[1]+rn, c[2]+dz*rn) | |
group.objs.append( create( level-1, c2, r/2.0)) | |
return group | |
def run( n, level): | |
scene = create( level, Vec(0, -1, 0), 1) | |
out = open("image.pgm","w") | |
out.write( "P5\n" + str(n) + " " + str(n) + "\n255\n") | |
for y in range( n-1, -1, -1): | |
for x in range( 0, n, 1): | |
d = Vec( x - (n/2.0), y - (n/2.0), n) | |
ray = Ray( Vec( 0, 0, -4), unitize( d)) | |
g = ray_trace( unitize( Vec( -1, -3, 2)), ray, scene) | |
out.write( chr( int(0.5 + (255.0 * g)))) | |
out.close() | |
if __name__ == "__main__": | |
import sys | |
if "--run" in sys.argv: | |
run( int(sys.argv[3]), int(sys.argv[2])) | |
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run with
pypy Ray.py --run 5 512
convert image.pgm image.png