Tuesday 11 March 2014

FreeCAD: Simple Engine Animation.


A very simple animation to show the basics:


I do not have the time needed to go on detail plus this information will be obsolete once FreeCAD has an assembly module. So I'm posting just what I have.

Steps to animate something inside FreeCAD:


-Create parts

-Export them to STEP

-Create new document and import parts

-Determine how FreeCAD names the parts (in my script you can see "Part_Feature003", or "Part_Feature")

-Create a function that defines mathematically the mechanism (crank-slider type in mine, very simple)

-Create a timer that calls the function to make it move (look at the end of the script)


This is the python script, you can download parts here:


from PyQt4 import QtCore, QtGui

import Part
from FreeCAD import Base
import math as mt

i=0
def engine():
  global i
  
  i+=0.1
  
  cig=mt.degrees(i)
  
  
  B=mt.asin((mt.cos(i)*40.0)/140.0)
  AB=mt.asin((mt.sin(i)*(40.0/140.0)))
  PP=mt.cos(i)*40.0+mt.cos(AB)*140.0
  alphaB=mt.radians(90.0)-B
  
  br=FreeCAD.Rotation(FreeCAD.Vector(0,0,1),alphaB)
  bd=App.Vector(mt.sin(i)*40,mt.cos(i)*40.0,20.0)
  bdgc=FreeCAD.Vector(mt.sin(i)*40,mt.cos(i)*40.0,20.0)
  
  App.getDocument("montadoanimacion").Part__Feature002.Placement=App.Placement(App.Vector(0,0,0),App.Rotation(FreeCAD.Vector(0,0,1),-cig))
  
  #biela
  
  App.getDocument("montadoanimacion").Part__Feature003.Placement=App.Placement(bd,App.Rotation(FreeCAD.Vector(0,0,1),(mt.degrees(AB))))
  
  #piston
  
  App.getDocument("montadoanimacion").Part__Feature.Placement=App.Placement(App.Vector(0,PP-35,30),App.Rotation(-0.5,0.5,0.5,0.5))

timer=QtCore.QTimer()
timer.timeout.connect(engine)
timer.start(10)



Open the file and then copy-paste this script. It should move. 

That's all.

Now I hope to see how people creates new and more complex animations :)


Bye!