BGE: realtime random shape generator (python)

Question

I want to set up a script that randomly changes the shape of an object. What I have so far is:

from bge import logic
import random

cont = logic.getCurrentController()
object = cont.owner


for mesh in object.meshes:
   for m_index in range(len(mesh.materials)):
      for v_index in range(mesh.getVertexArrayLength(m_index)):

         vertex = mesh.getVertex(m_index, v_index)
         vertex.setXYZ([ random.random(), random.random(), random.random()])

This works pretty well. However, since every single vertex gets its own random location, the cube turns out something like this:

what I want is something like this:

My question is: how can I achieve something like that?

I think the "broken" shapes happen because 3 vertices are connected to each other and if they all get a different random position, the shape "breaks"?

I assume, that I have to give the vertices 1-3 the same random position, then the vertices 4-6 the same random position and so on?

If that is true, how could I write that down in python?

Answer 1

I have modified the code as follows :

• added a dictionary that stores the vertex position and the generated offset by random.uniform()
• for each vertex check if there is already an offset for this position , if so we add this offset to the old position
• if there is no offset calculated for this position we generate a new one and store it in the dictionary, we also add it to the old position

this method gives the vertices that has the same position the same offseet

---

from bge import logic
import random
from mathutils import Vector

cont = logic.getCurrentController()
object = cont.owner

for mesh in object.meshes:
   print(mesh)
   verts_shift = dict()
   for m_index in range(len(mesh.materials)):
      print(m_index)
      for v_index in range(mesh.getVertexArrayLength(m_index)):
         print(v_index)
         vertex = mesh.getVertex(m_index, v_index)
         xyz_old= vertex.getXYZ().freeze()
         xyz_shift = verts_shift.get(xyz_old, None) 
         if xyz_shift :
             vertex.setXYZ(xyz_old+xyz_shift)
         else :
             xyz_shift = Vector(( random.uniform(-0.5,0.5), random.uniform(-0.5,0.5), random.uniform(-0.5,0.5) ))
             verts_shift[xyz_old] = xyz_shift
             vertex.setXYZ(xyz_old+xyz_shift)           

         print(xyz_old, xyz_shift)

---