Octree Visualization, toxiclibs

devinj898

Octree Visualization, toxiclibs

in Contributed Library Questions • 2 years ago

I have been using different parts of the toxiclibs library for a while now, specifically the octree section. However, I haven't been able to figure out how to export the cubes that the octree creates as it processes the subdivision of space.

Any thoughts?

Replies(1)

toxmeister

Re: Octree Visualization, toxiclibs

2 years ago

The visitor pattern is a great tool for things like this and the example below demonstrates how to apply this to an octree... Hope that helps!

/**
* This example demonstrates the application of the Visitor design pattern to build a 3D mesh
* of all boxes surrounding each node in a PointOctree. It uses an interface called OctreeVisitor
* whose implementation will be recursively applied to each node. Separating the actual function
* of building the mesh from all the recursive parts inherent with tree structures, not only
* simplifies the code but also provides a general mechanism to process tree nodes without
* having to resort to other (more complex) mechanisms like inheritance etc. Links about the
* concepts used are in the comments further below.
*
* The demo first creates a sphere mesh and places all vertices in the octree. Then the mesh of
* the tree hierarchy is built and exported as STL model.
*
* toxiclibs version 0021 onwards will contain the OctreeVisitor interface and applyVisitor() method.
* An updated/simplified version will be bundled with these future releases.
*/
/*
*
* This demo & library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* http://creativecommons.org/licenses/LGPL/2.1/2
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
import toxi.geom.*;
import toxi.geom.mesh.*;
import toxi.processing.*;
float radius=200;
ToxiclibsSupport gfx;
TreeMeshBuilder builder;
void setup() {
size(640, 480, P3D);
gfx=new ToxiclibsSupport(this);
// create the root node of the octree
PointOctree tree=new PointOctree(new Vec3D(-radius, -radius, -radius), radius*2);
tree.setMinNodeSize(2);
// create a sphere mesh (slightly smaller than tree max bounds)
Mesh3D sphere=new Sphere(radius*0.9).toMesh(20);
// add all sphere vertices to tree
tree.addAll(new ArrayList<Vec3D>(sphere.getVertices()));
// starting at the root node, recursively apply the mesh builder (see below) as visitor to all nodes
builder=new TreeMeshBuilder();
applyVisitor(tree, builder);
// export mesh
builder.mesh.saveAsSTL(sketchPath("octree.stl"));
}
void draw() {
background(255);
noFill();
stroke(0, 100);
translate(width/2, height/2, 0);
rotateX(mouseY*0.01);
rotateY(mouseX*0.01);
// display the box mesh
gfx.mesh(builder.mesh);
}
// recursive function applying a visitor to all nodes in the tree
void applyVisitor(PointOctree node, OctreeVisitor visitor) {
visitor.visitNode(node);
if (node.getNumChildren()>0) {
for (PointOctree c : node.getChildren()) {
if (c!=null) {
applyVisitor(c, visitor);
}
}
}
}
/**
* This interface is part of the Visitor design pattern mechanism:
* http://en.wikipedia.org/wiki/Visitor_pattern
* http://en.wikipedia.org/wiki/Interface_(object-oriented_programming)
*/
interface OctreeVisitor {
/**
* Applies the procedure defined by an implementation of this interface to
* the given tree node.
*
* @param node a tree node
*/
void visitNode(PointOctree node);
}
/**
* This class is a tree visitor implementation and creates a triangle mesh of
* all octree nodes.
*/
class TreeMeshBuilder implements OctreeVisitor {
TriangleMesh mesh=new TriangleMesh();
void visitNode(PointOctree node) {
// OctreeNodes are AABBs and therefore have a toMesh() method
mesh.addMesh(node.toMesh());
}
}

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