Hi, I’m trying to build an L-System in 3d with OF. In order to do this, i generate a mesh, I apply a transformation to it, and i draw the mesh. The problem is that after transforming the mesh a couple of times, i want to go back to the original position. How can I achieve this?

I’ve tried `ofPushMatrix`

and `ofPopMatrix`

, but they are not working as expected, once i pop the matrix out, the position is not where I left it before.

That’s the code that decide which transformation to apply to the mesh:

```
void Transformer::generate(ofVboMesh& mesh, string _instruction, int depth) {
instructions = _instruction;
for (int i = 0; i < instructions.length(); i++) {
char c = instructions[i];
if (c == 'F') {
addBranchIntoMesh(branch, mesh, length, "cube");
transform.translate(0, 0, length);
branch.setCurrentTransform(transform);
}else if( c == 'G') {
transform.translate(0, 0, length);
branch.setCurrentTransform(transform);
}else if (c == '+') {
transform.rotate(+theta, 0, 1, 0);
branch.setCurrentTransform(transform);
}
else if (c == '-') {
transform.rotate(-theta, 0, 1, 0);
branch.setCurrentTransform(transform);
}
else if (c == '[') {
branch.setCurrentTransform(branch.getCurrentTransform());
ofPushMatrix();
}
else if (c == ']') {
ofPopMatrix();
}
}
currentDepth++;
}
void Transformer::addBranchIntoMesh(Branch branch, ofVboMesh& mesh, float length, string geometry){
if(geometry == "cube") {
cube.generate(mesh, currentDepth, length, branch.getCurrentTransform());
}
}
```

The Branch class simply store the previous transformation and get the current one

```
#pragma once
#include "ofMain.h"
class Branch {
public:
Branch(
const ofMatrix4x4& currentTransform = ofMatrix4x4()
);
ofMatrix4x4 currentTransform;
ofMatrix4x4 getCurrentTransform() const { return currentTransform; }
void setCurrentTransform(const ofMatrix4x4& transform) { this->currentTransform = transform; }
};
```

The cube class, take the general mesh (the mesh that will contain all the cubes), and put into it a cube, a the position specified by the transformation.

```
void Cube::generate(ofMesh& mesh, int depth, unsigned int length, ofMatrix4x4 transformation){
ofColor color(255, 0, 0);
float hue = 254.f;
vertices = createCube(length);
// for the sake of brevity i will not include the createCube ;)
for (unsigned i = 0; i < vertices.size(); ++i){
mesh.addVertex(vertices[i] * transformation);
mesh.addNormal(normals[i]);
mesh.addTexCoord(ofVec2f(0.f, depth));
mesh.addColor(color);
}
}
```

I’m also not sure if ofMatrix4x4 fits my needs, that is basically move a turtle back and forth on the screen and drawing a mesh where is it needed.

Any suggestion is more than appreciated!