Whether to calculate contacts for all simulation sub-steps or only the first sub-step.
When simulation sub-stepping is enabled with Physics2D.useSubStepping, this property is used to control the whether or not contacts are calculated for all sub-steps or only the first sub-step.
When enabled, contacts are calculated for all sub-steps. This provides a more accurate simulation for each sub-step but will reduce performance. In most cases, this extra contact calculation isn't required.
When disabled, contacts are only calculated for the first sub-step. Subsequent sub-steps only perform integration and constraint solving. This increases performance whilst still maintaining a stable simulation. In most cases, this should be used.
See Also: Physics2D.useSubStepping, Physics2D.minSubStepFPS, Physics2D.maxSubStepCount, PhysicsScene2D.subStepCount and PhysicsScene2D.subStepLostTime.