29. 3D Structure

We will use a Python script to create a pyramid structure for the next tutorial.

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There are many ways to create structures, such as box modeling. With a Python script (or alternatively, using an addon), we can create structures depending on a set of parameters.

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To create a 3D structure, we need a list of 3D points. These points are (x,y,z) numbers. Besides these, our scripts also has to have list of all faces.

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Faces are 3-vertex or 4-vertex points arranged in a right-handed loop. When the mesh is loaded into jMonkey, any quads will be converted to triangles.

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This shows a planes. In addition to giving the locations of 1, 2, 3 and 4, we have to give the face. We can give the quad (1,2,3,4) or triangles (1,2,3) and (1,3,4). It can also be broken as (1,2,4) and (2,3,4) triangles.

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By running the python script (pyramid.py), in the text editor and then clicking run script, a 3D structure is created. Save the blender file, as pyramid.blend as it will be used later.

# pyramid.py

import bpy

def createMesh(name, origin, verts, faces):
    me = bpy.data.meshes.new(name+'Mesh')
    ob = bpy.data.objects.new(name, me)
    ob.location = origin
    ob.show_name = True
    bpy.context.scene.objects.link(ob)
    me.from_pydata(verts, [], faces)
    me.update(calc_edges=True)
    return ob
 
def run(s,d,h,Level,origin):
    verts = []
    faces = []
    for lev in range(Level):
        # Outer Square (z = lev*h)
        sd = s - lev*d
        z = lev*h
        verts.append((-sd/2,-sd/2,z)) # 0+lev*8
        verts.append((sd/2,-sd/2,z)) # 1+lev*8
        verts.append((sd/2,sd/2,z)) # 2+lev*8
        verts.append((-sd/2,sd/2,z)) # 3+lev*8
        # Inner Square (do not do for last level)
        if lev!=Level-1:
            verts.append((-(sd-d)/2,-(sd-d)/2,z)) # 4+lev*8
            verts.append(((sd-d)/2,-(sd-d)/2,z)) # 5+lev*8
            verts.append(((sd-d)/2,(sd-d)/2,z)) # 6+lev*8
            verts.append((-(sd-d)/2,(sd-d)/2,z)) # 7+lev*8
        # add Faces
        if lev!=0:
            # not first level
            a1 = 4+(lev-1)*8, 5+(lev-1)*8, 1+lev*8, 0+lev*8
            a2 = 5+(lev-1)*8, 6+(lev-1)*8, 2+lev*8, 1+lev*8
            a3 = 6+(lev-1)*8, 7+(lev-1)*8, 3+lev*8, 2+lev*8
            a4 = 7+(lev-1)*8, 4+(lev-1)*8, 0+lev*8, 3+lev*8
            faces.extend((a1,a2,a3,a4))
        if lev!=Level-1:
            a1 = 3+lev*8, 0+lev*8, 4+lev*8, 7+lev*8
            a2 = 0+lev*8, 1+lev*8, 5+lev*8, 4+lev*8
            a3 = 1+lev*8, 2+lev*8, 6+lev*8, 5+lev*8
            a4 = 2+lev*8, 3+lev*8, 7+lev*8, 6+lev*8
            faces.extend((a1,a2,a3,a4))
        else:
            a1 = 0+lev*8, 1+lev*8, 2+lev*8, 3+lev*8
            faces.append(a1)
    ob1 = createMesh('Pyramid', origin, verts, faces)
    
if __name__ == "__main__":
    run(s = 5, # base side
        d = 1, # side decrement
        h = 0.5, # height increment
        Level = 5, # levels
        origin = (0,0,0)) # location

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