[Visualpython-users] Normals

[Poul R. <Pou...@sk...>]

I still can't see in the manual how two to specify different normals at
different vertices in the faces object.
I tried
triangle=faces(pos=[v1,v2,v3],normal=[n1,n2,n3],color=c)
but it didn't work. On the other hand, replacing color=c with
color=[c1,c2,c1] works fine.

The example below works, but not if I replace normal=n12 with
normal=[n1,n12,n12]

One further question: How can I make a copy of ny adjacent triangles
before rotating them? I tried __copy__() but couldn't make it work.

Poul Riis




from visual import *

def triangle3d(v1,v2,v3,trianglecolor):
    c = color.hsv_to_rgb(trianglecolor)
    n = norm(cross(v2-v1,v3-v1))
    triangle1=faces(pos=[v1,v2,v3],normal=n,color=c)
    triangle2=faces(pos=[v2,v1,v3],normal=-n,color=c)

def
adjacenttriangles3d(v1,v2,v3,v4,trianglecolor1,trianglecolor2,rotateang):
    c1 = color.hsv_to_rgb(trianglecolor1)
    c2 = color.hsv_to_rgb(trianglecolor2)
   
backsidecolor1=(1-trianglecolor1[0],trianglecolor1[1],trianglecolor1[2])
   
backsidecolor2=(1-trianglecolor2[0],trianglecolor2[1],trianglecolor2[2])  
 
    bsc1 = color.hsv_to_rgb(backsidecolor1)
    bsc2 = color.hsv_to_rgb(backsidecolor2)    
    n1 = norm(cross(v2-v1,v4-v1))
    n2 = norm(cross(v3-v2,v4-v3))
    n12 = norm((n1+n2)/2)
    twotriangles=frame()
    faces(frame=twotriangles,pos=[v1,v2,v4],normal=n12,color=[c1,c2,c1])
    faces(frame=twotriangles,pos=[v2,v3,v4],normal=n12,color=[c2,c1,c2])
    faces(frame=twotriangles,pos=[v2,v1,v4],normal=-n12,color=bsc1)
    faces(frame=twotriangles,pos=[v3,v2,v4],normal=-n12,color=bsc2)
    twotriangles.rotate(angle=rotateang, axis=(1,0,0), origin=(0,0,0))

scene=display(title="Two adjacent
triangles",width=600,height=600,forward=(-2,-1,-0.5),up=(0,0,1),background=(1,1,1))

# Grid in xy-plane:
for i in range(-10,11,1):
    gridlinesx=curve(pos=[(i,-10,0),(i,10,0)],color=crayola.black)
    gridlinesy=curve(pos=[(-10,i,0),(10,i,0)],color=crayola.black)

# Axes:
xaxis=arrow(pos=(-10,0,0),axis=(20,0,0),shaftwidth=0.02,color=crayola.green)
yaxis=arrow(pos=(0,-10,0),axis=(0,20,0),shaftwidth=0.02,color=crayola.green)
zaxis=arrow(pos=(0,0,-10),axis=(0,0,20),shaftwidth=0.02,color=color.hsv_to_rgb((0.8,0.7,0.9)))

# Four points, A, B, C, and D:
A=vector(5,0,0)
B=vector(8,10,0)
C=vector(0,7,0)
D=vector(0,0,15)

# Objects:

adjacenttriangles3d(A,B,C,D,(0.5,1,0.95),(0.75,1,0.95),pi/4.)