World Physics

../../_images/game-engine_physics_world_panel.png

BGE World Physics Panel.

Physics Panel

The Game Physics located in the World panel determine the type of physical rules that govern the Game Engine scene, and the gravity value to be used. Based on the physics engine selected, in physics simulations in the Game Engine, Blender will automatically move Actors in the downward (-Z) direction. After you arrange the actors and they move as you wish, you can then bake this computed motion into keyframes (see Digging Deeper for more info).

Physics Engine

Set the type of physics engine to use.

Bullet
The default physics engine, in active development. It handles movement and collision detection. The things that collide transfer momentum to the collided object.
None
No physics in use. Things are not affected by gravity and can fly about in a virtual space. Objects in motion stay in that motion.
Gravity
The gravitational acceleration, m.s-2 (in units of meters per squared second), of this world. Each object that is an actor has a mass and size slider. In conjunction with the frame rate (see Render section), Blender uses this info to calculate how fast the object should accelerate downward.
Culling Resolution
The size of the occlusion culling buffer in pixel, use higher value for better precision (slower). The optimized Bullet DBVT for view frustum and occlusion culling is activated internally by default.
Physics Steps
Max
Sets the maximum number of physics steps per game frame if graphics slow down the game. higher value allows physics to keep up with realtime.
Substeps
Sets the number of simulation substeps per physics timestep. Higher value give better physics precision.
FPS
Set the nominal number of game frames per second. Physics fixed timestep = 1/fps, independently of actual frame rate.
Logic Steps
Sets the maximum number of logic frame per game frame if graphics slows down the game, higher value allows better synchronization with physics.
Physics Deactivation

These settings control the threshold at which physics is deactivated. These settings help reducing the processing spent on Physics simulation during the game.

Linear Threshold
The speed limit under which a rigid body will go to sleep (stop moving) if it stays below the limits for a time equal or longer than the deactivation time (sleeping is disabled when deactivation time is set to 0).
Angular Threshold
Same as linear threshold, but for rotation limit (in rad/s)
Time
The amount of time in which the object must have motion below the thresholds for physics to be disabled (0.0 disables physics deactivation).

Obstacle Simulation

Simulation used for obstacle avoidance in the Game Engine, based on the RVO (Reciprocal Velocity Obstacles) principle. The aim is to prevent one or more actors colliding with obstacles.

See Path finding and steering behaviors for more details.

Type
None
Obstacle simulation is disabled, actors are not able to avoid obstacles.
RVO (cells)
Obstacle simulation is based on the RVO method with cell sampling.
RVO (rays)
Obstacle simulation is based on the RVO method with ray sampling.
Level height
Max difference in heights of obstacles to enable their interaction. Used to define minimum margin between obstacles by height, when they are treated as those which are situated one above the other i.e. they does not influence to each other.
Visualization
Enable debug visualization for obstacle simulation.