Envelope Editor



One of the most useful features in PS2 is the ability to envelope almost any parameter. Particle Storm has its own custom Envelope, which works very similarly to LightWave's standard Envelope, but has a few extra features, making it a lot easier to use.


Envelope Parameters:
Next to almost every parameter, you will see a control like this:
Clicking on it will display a popup.
Notice the contents of the popup:
  • Constant: a constant integer or decimal point number.
  • Envelope: Particle Storm's custom Envelope editor.
  • Layout Item: Just like "texture reference objects" in LightWave. Any parameter can be associated with any positional attribute of a Layout item.

Now select "Envelope" for an overview of the Envelope controls.

  • Clear: Clears the entire envelope including all settings.

  • Load: Load a standard LightWave ".env" file.

  • Save: Save out a special Particle Storm envelope.

  • End: End behavior controls the ending characteristics of a range of keyframes. The diagram below explains them.



  • Reset will set the value of the key immediately after the last key to zero.

  • Stop will maintain the value of the last key linearly for the remaining frames.

  • Repeat will start from the first key again right after the last key created. The behavior will repeat forever.

  • PingPong is similar to Repeat, but it will essentially mirror the range of keys for each repeat cycle, therefore creating smoother motion.


  • Mouse Input: Create/Delete/Drag will allow the creation, deletion and moving of a key.


    • To create a key, simply left click anywhere inside the envelope grid. A key will be created at the location of the mouse cursor.
    To drag a key, hold down the left mouse button on the key and move the mouse up and down. This will alter the key's value. Moving the mouse left and right will alter the current frame.
    To drag a range of keys, hold down the [ctrl] key on your keyboard and select the keys by left clicking on them. Let go of the [ctrl] key and drag the mouse to move the keys around.

  • Pan /Zoom/AutoSize will allow you to pan and zoom around in the envelope view. If you get lost, hit the Auto Size button to center the view to where your keys are created.
  • Current key scrolls through and selects keys.

  • Value: Displays the value at the current key. Change this parameter to alter the value at that key.

  • Linear: When on, this creates a linear transition between the current and the key immediately preceeding it.


    • LinearNon Linear

  • TCB: Allows you to interactively adjust the tension, continuity and bias of a key.

    To adjust Tension, click on a key and hit "t" on the keypad. Similarly, bias is "b", and continuity is "c".



Let's animate the Heading of a Fountain Emitter using envelopes.
    1) Clear the project.
    2) Select Fountain under controllers.
    3) Expand the heading parameter.
    Note that all values are constant. Click on the edit box next to heading and change this to "Envelope".
    4) Now click on "edit envelope". This will bring up the envelope dialog.
    5) Set the end behavior to "Repeat".
    6) Create a key at frame 30 and set its value to 180. (You don't have to do this numerically. The key value will be set to the horizontal position of the mouse cursor, and the value will be set as a function of the vertical position of the mouse cursor).
    7) Create a key at frame 60 and set its value to 0.
    8) Play the animation. Notice the heading of the emitter cone now moves from side to side indefinately.
    9) While the preview window is still playing, go back into the envelope editor and change the values by dragging the keys around. Notice how the OpenGL preview window reflects your changes in real time.