Adobe Director Basics

ADOBE DIRECTOR BASICS
3D: Controlling action
Physics world
Before you can use a Physics cast member to simulate a physical world, you need to initialize the cast member. To do
this, you need to call physicsMember.init(). To get the simulation to run, you need to call physicsMember.simulate()
once per frame.
Initialization
The init() command takes five parameters:
The 3D cast member which contains the scene to be simulated
A scalingFactor vector (whose value is ignored in Director 11.5)
A timeStepMode, whose value may be #automatic or #equal.
A timeStep, whose value is ignored if you choose #automatic for the mode. If you want to use the #equal mode
with the same results as if you were using the #automatic mode, you can use 1.0 / _movie.frameTempo for the
timeStep.
The number of subSteps to use between each screen update. More subSteps create more realistic simulations, but
use more processing time. A recommended value for this parameter is 5.
The following lines of code initialize the Physics member named "Physics" to use the 3D member named “3D” for a
simulation in real time:
-- Lingo syntax
vPhysics = member("Physics")
v3DMember = member("3D")
vScale = vector(1, 1, 1) -- necessary but ignored
vMode = #automatic
vTimeStep = 1.0 / _movie.frameTempo -- ignored in this case
vSubSteps = 5
vPhysics.init(v3DMember, vScale, vMode, vTimeStep, vSubSteps)
// JavaScript syntax
vPhysics = member("Physics");
v3DMember = member("3D");
vScale = vector(1, 1, 1); // necessary but ignored
vMode = symbol("automatic");
vTimeStep = 1.0 / _movie.frameTempo; // ignored in this case
vSubSteps = 5;
vPhysics.init(v3DMember, vScale, vMode, vTimeStep, vSubSteps);
timeStepMode
The following are the two possible values for timeStepMode.
#automatic: In this mode, the Physics simulation calculates how much time has elapsed since the last update, and
moves the simulation forward by that amount of time. This mode is easier to work with, but it may break down if
there are long interruptions between updates. For example, if the user switches to another application and back, or
if a lengthy process in the movie itself monopolizes the computer processor.
#equal: In this mode, the Physics simulation advances by the same time interval on every update. If the timeStep
is equal to the duration of a Director frame (1.0 / _movie.frameTempo), then the result is almost equivalent to
using the #automatic mode with better recovery after long interruptions. If the timeStep is significantly different
from the duration of a Director frame, then the animation may seem to run too fast or too slow. In particular, if
your movie is unable to play at the expected frame rate on a slow machine, the entire scene may update slowly.
Last updated 8/26/2011
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