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from visual import *
# Create a surface of revolution out of slices that are convex objects
# By David Scherer
def draw_slice(sweep, r, axis, frame, color):
# comment in this line to see where the slices are:
#color=(uniform(0,1),uniform(0,1),uniform(0,1))
ls = len(sweep)
pos = zeros( (len(r)*ls, 3), float64 )
for j in range(len(r)):
pos[j*ls:j*ls+ls] = sweep*r[j] + (axis[j],0,0)
return convex(pos=pos,
frame = frame,
color = color,
)
def revolution(radius, length, slices=32, color = (1,1,1), pos = (0,0,0)):
r = absolute(radius) # radius is a list of radii for all the slices
# sweep = unit circle in the yz plane
t = arange(0,2*pi,2*pi/slices)
sweep = zeros( (slices,3), float64) # Numeric array (rows=slices)*(columns=3)
sweep[:,1] = cos(t) # set middle column to cos(t)
sweep[:,2] = sin(t) # set final column to sin(t)
# axis[i] = center of the ith slice of the surface
axis = arange(0,length,float(length)/len(r))
group = frame(pos = pos)
start = 0
for i in range(1,len(r)-1):
# if concave, show all convex slices up this point
if (r[i+1] + r[i-1] - 2*r[i]) >= 0: # have encountered concave region
draw_slice(sweep,r[start:i],axis[start:i], group, color)
start = i-1
draw_slice(sweep,r[start:],axis[start:], group, color)
return group
if __name__ == '__main__':
scene.autocenter = 1
t = arange(0,1,0.02)
s = revolution(sin(t*12.)*0.5 + 1.0, 5.0, pos=(3,0,0), color=color.red)
s.axis = (0,1,0)
glass = revolution( [0.5, 0.1, 0.1, 0.1, 0.1, 0.2, 0.3, 0.4, 0.5],
length=5.0,
color=color.yellow)
glass.axis = (0,1,0)
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