Populating SpeeTree instances with a SWA file.

Hello,

I am trying to parse a SWA file and place a mass amount of SpeedTree trees. See SWA format below:

https://docs.speedtree.com/doku.php?id=swa_files

I can parse the file just fine but I am stuck on how to deal with the up/right vectors and scale values to properly position, rotate and scale the tree. My efforts so far produce lots of anomalies. The trees appear to move or shrink/grow as I move the camera, some trees are not rotated correctly, and more ugliness. I took a shot at using Matrix4x4 and SetTRS but this stuff is above my pay grade. My rough parser/populate function is below, any advice is greatly appreciated.

 public void getFoliage(){
         
         string line = "";
         int sectionCount = 0;
         string species = "none";
         string subSpecies = "none";
         string file = "none";
 
         string path = Application.dataPath + "/test.swa";
         StreamReader sr = new StreamReader (path);
 
         if (sr != null) {
 
             while (!sr.EndOfStream) {
 
 
                 line = sr.ReadLine ();
 
                 //see if we have encountered a new section of foliage in the swa file
                 if (line.Contains ("/")) {
 
                     //get the species info
                     string[] speciesInfo = line.Split("/"[0]);
                     species = speciesInfo [0];
                     subSpecies = speciesInfo [1];
                     file = speciesInfo [2].Remove(speciesInfo [2].Length - 4);
 
                     //get the count of this section
                     sectionCount = int.Parse (sr.ReadLine());
 
                 
 
                     for (int i = 0; i <= sectionCount -1; i++)
                     {
                         //read and splt the line in
                         string[] temp = sr.ReadLine ().Split (" " [0]);
 
                         //create the position, up vector, right vector and scale
                         //note ST uses Z as up so we swap the values when assinging them
                         Vector3 position = new Vector3(float.Parse(temp[0]),float.Parse(temp[2]),float.Parse(temp[1]));
                         Vector3 upVector = new Vector3 (float.Parse (temp [3]), float.Parse (temp [5]), float.Parse (temp [4]));
                         Vector3 rightVector = new Vector3 (float.Parse (temp [6]), float.Parse (temp [8]), float.Parse (temp [7]));
                         float scale = float.Parse (temp [9]);
 
                         //create a vector3 for scaling in Unity
                         Vector3 scalerVal = new Vector3 (scale, scale, scale);
 
                         //create the rotation vector?    
                         Vector3 v3 = Vector3.Cross (upVector, rightVector).normalized * Mathf.Rad2Deg;
                         Quaternion rotation = Quaternion.Euler(v3.x, v3.y, v3.z);
 
 
 
                         //instantiate the object
                         GameObject tempSt = (Instantiate(Resources.Load(file), position,  Quaternion.identity) as GameObject);
 
                         //create an array of mesh filters to hold the tree and its LOD meshes                            
                         Component[] mf;
                         mf = tempSt.transform.GetComponentsInChildren<MeshFilter>();
                                                 
                         int filter = 0;
                         foreach (MeshFilter m in mf) {
                                                             
                             Vector3[] origVerts;
                             Vector3[] newVerts;
                             
                             origVerts = m.mesh.vertices;
                             newVerts = new Vector3[origVerts.Length];
                             
                             Matrix4x4 mt = Matrix4x4.identity;
                             mt.SetTRS(position, rotation, scalerVal);
                             
                                                         
                             int t = 0;
                             while (t < origVerts.Length) {
                                                                 
                                 newVerts[t] = mt.MultiplyPoint3x4(origVerts[t]);
                                 t++;
                             }
                             
                             m.mesh.vertices = newVerts;
                             
                         
                         }
 
 
                         }
 
                 }
     
             }
 
 
             sr.Close();
         }
 
     }
 }