Re: [Visualpython-users] Normals

[Bruce S. <Bru...@nc...>]

You ought to be able to specify a list of normals in the constructor for 
faces, but as you found, you can't; it's a bug. The only workaround is 
to do something like this:

triangle1=faces(color=c)
triangle1.append(pos=v1,normal=n1)
triangle1.append(pos=v2,normal=n2)
triangle1.append(pos=v3,normal=n3)

Please be specific about your difficulty with copy; best would be a 
short example. Note from the Visual documentation that there are issues 
with copying objects that are in frames:

__copy()__ Makes a copy of an object. There are two underscores before 
and after the copy(). Without any arguments, this results in creating a 
second object in the exact same position as the first, which is probably 
not what you want. The __copy__() function takes a list of keyword=value 
argument pairs which are applied to the new object before making it 
visible. For example, to clone an object from one display to another, 
you would execute: new_object = old_object.__copy__( 
display=new_display). Restriction: If the original object is within a 
frame, and the new object is on a different display, you must supply 
both a new display and a new frame for the new object (the new frame may 
be None). This is due to the restriction that an object may not be 
located within a frame that is in a separate display. The attribute 
__members__ used to give a list of all the object's attributes but is no 
longer available in VPython. Its main use was in copying objects.

Poul Riis wrote:
> 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.)
> 
> 
> -------------------------------------------------------------------------
> This SF.Net email is sponsored by the Moblin Your Move Developer's challenge
> Build the coolest Linux based applications with Moblin SDK & win great prizes
> Grand prize is a trip for two to an Open Source event anywhere in the world
> http://moblin-contest.org/redirect.php?banner_id=100&url=/
> _______________________________________________
> Visualpython-users mailing list
> Vis...@li...
> https://lists.sourceforge.net/lists/listinfo/visualpython-users