Cube to sphere

Code Snippets
1

Technology applied to the planets, asteroids

Before:


After:


Code:

planet.7z (11.1 KB)

F3 - Mode Wireframe

2

Thank you for this - I’m quite interested in procedural model deformation techniques :slight_smile: !

However, I would like to point out that it can be done faster & simpler by just normalizing the vertex position vectors:

# -*- coding: utf-8 -*-   
from direct.showbase.ShowBase import ShowBase
from pandac.PandaModules import *
from math import sqrt
 
class MyApp(ShowBase):
 
    def __init__(self):
    
        ShowBase.__init__(self)
        
        planet = loader.loadModel('planet')
        planet.reparentTo(render)
        
        geomNodeCollection = planet.findAllMatches('**/+GeomNode')
        
        for nodePath in geomNodeCollection:
        
            geomNode = nodePath.node()
    
            for i in range(geomNode.getNumGeoms()):

                geom = geomNode.modifyGeom(i)

            vdata = geom.modifyVertexData()

            vertex = GeomVertexRewriter(vdata, 'vertex')
    
            while not vertex.isAtEnd():

                v = Vec3(vertex.getData3f())
                v.normalize()
                vertex.setData3f(v)

        self.accept("f3", self.toggleWireframe)

app = MyApp()
app.run()

Another advantage of the above code is that it works with any model, while your code will crash with a “math domain error” ValueError when a vertex lies too far from the model origin.

It’s also possible to “spherify” a model to a certain degree (instead of making it an exact unit-radius sphere) by slightly modifying the new code:

# -*- coding: utf-8 -*-   
from direct.showbase.ShowBase import ShowBase
from pandac.PandaModules import *
from math import sqrt
 
class MyApp(ShowBase):
 
    def __init__(self):
    
        ShowBase.__init__(self)
        
        planet = loader.loadModel('planet')
        planet.reparentTo(render)
        # the bigger the strength of the spherify effect, the closer the model
        # gets to a unit-radius sphere
        spherify_strength = 3.
        power = 1. / spherify_strength
        
        geomNodeCollection = planet.findAllMatches('**/+GeomNode')
        
        for nodePath in geomNodeCollection:
        
            geomNode = nodePath.node()
    
            for i in range(geomNode.getNumGeoms()):

                geom = geomNode.modifyGeom(i)

            vdata = geom.modifyVertexData()

            vertex = GeomVertexRewriter(vdata, 'vertex')
    
            while not vertex.isAtEnd():

                v = Vec3(vertex.getData3f())
                new_length = v.length() ** power
                v.normalize()
                v *= new_length
                vertex.setData3f(v)

        self.accept("f3", self.toggleWireframe)

app = MyApp()
app.run()

But I’m actually wondering if this couldn’t be done with just a matrix. Then a vdata.transform_vertices(matrix) call could replace the entire while-loop. If anyone has any ideas if such a matrix exists and what it looks like, I’d love to hear it. (Would also be interesting for other model deformation techniques, like taper, bend, etc.)

Thank you again, serega-kkz, for your work! I hope you don’t mind my comments & changes.

3

Your method is fast, but not flexible. Now Imagine you need to calculate the height map at Black and white texture.

How do you do? )

4

It seemed to me that the purpose of your code was only to change the shape of a model; my apologies if I misunderstood.
If your intent is to simultaneously process the vertex data for other purposes as well, then you are right, of course.