// TailFins Script - User selects object to use as tail fin
// N copies of the original are made and positioned for
// the radius of the rocket (User is asked for N and radius)

scene = window.getScene();
sel = scene.getSelection(); // Find out what user selected

// Check to make sure user really did select 1 object
if (sel.length != 1 ) {
  new MessageDialog(window, "Please select an object aligned as the first tail fin.");
  return;
}

info = scene.getObject(sel[0]);
mesh = info.object;

// Ask the user how many tail fins and what radius to use.
numFinsField = new ValueField(3, ValueField.POSITIVE);
bodyRadiusField = new ValueField(0.5, ValueField.POSITIVE);
dlg = new ComponentsDialog(window, "How many rocket tail fins & radius",
    new Widget [] {numFinsField, bodyRadiusField}, new String [] {"Number?", "Body Radius?"});
if (!dlg.clickedOk()) return;
numFins = numFinsField.getValue();
bodyRadius = bodyRadiusField.getValue();
rotDelta = 360.0/numFins;
rotDeltaRad = Math.PI* rotDelta/180;
orginalCoord = info.getCoords();
 
for (i=0; i<numFins; i++) { // do for each rocket fin
   // duplicate our original object 
   fin = mesh.duplicate();
   
   // rotation is adjusted for each fin
   radRotation = rotDeltaRad * i;
   
   // rotation is accomplished through a rotation matrix
   rotMatrix = Mat4.yrotation(radRotation);
   // the fin is also shifted based upon the radius
   tranMatrix = Mat4.translation(bodyRadius, 0.0, 0.0);
   // the rotate and shift are combined with a matrix multiply
   compositeM = rotMatrix.times(tranMatrix);
   
   // apply the transform to a coordinate system
   newCoordSys = orginalCoord.duplicate();
   newCoordSys.transformCoordinates(compositeM); 
 
   // add the new transformed object to the scene
   window.addObject(fin, newCoordSys, "fin"+i, null); 
}