Scene Configuration

When creating the scene there are a few choices you can make. Most of these are passed to the scene when you create it:

var scene = new Physijs.Scene({ reportsize: 50, fixedTimeStep: 1 / 60 });

Scene constructor parameters

• fixedTimeStep default 1 / 60 This number determines how much time one simulation step is to simulate. The smaller the number, the more accurate (and slower) the simulation.
• broadphase default dynamic Specifies which broadphase will be used, choices are dynamic and sweepprune.
• reportsize default 50 As an optimization, world reports which contain object positions are pre-initialized based on this number. It's best to set this to the number of objects your scene will have.

Scene configuration methods

• setGravity default ( 0, -10, 0 ) Method which sets the amount and direction of gravitational forces. Usage: scene.setGravity(new THREE.Vector3( x_force, y_force, z_force ))
• setFixedTimeStep default 1 / 60 Resets the fixedTimeStep given in constructor. This method is meant for allowing on-the-fly physics accuracy configuration. Do not call it every frame!

Custom simulation steps

There are two parameters you can pass to the scene.simulate method: timeStep and maxSteps. timeStep specifies the amount of time to be simulated and defaults to the amount of time since the last iteration. maxSteps is an upper limit of the number of iterations the simulation may perform. The amount of time the simulator is told to run (timeStep) can be limited by the number of iterations allowed (maxSteps). For example:

If fixedTimeStep (see above) is 1 / 60 (16 milliseconds) and maxSteps is 5, the max time that can be simulated is maxSteps * fixedTimeStep = 0.08 seconds, or 80 milliseconds. If a timeStep less than or equal to 80ms is given, everything will be simulated, but if timeStep exceeds 80ms then not all of the time will be simulated. In this way maxSteps can be used to prevent the physics simulation from grinding to a complete halt if it starts getting overloaded. In the examples scene.simulate is called with parameters of ( undefined, 2 ) which tells Physijs to simulate as much as possible up to 2 iterations.