Manual Modules Dynamics Force Fields Drag Object
Drag Object Basic Coord. Shape Falloff FieldField
On the Field tab you can define the type of drag (angular, linear or axial) as well as its direction and strength.
Select the type of motion which the drag should affect: Linear, Angular or Axial.
The drag will affect linear motion, i.e. motion which changes the location of the body. Linear drag will be applied regardless of the direction in which the object is moving.
This type of drag will decelerate rotating bodies.
The Axial mode breaks the following law of physics:
Drag will always be applied in the opposite direction to the body’s motion.
The Axial mode breaks the law by allowing you to specify the direction of the drag (under Direction). Although it defies real world physics, the Axial mode helps you to take short cuts as demonstrated in the example below.
Strength [-10000000..10000000]
Use this to set the Strength of the drag force. Enter a high value if the objects should come to an abrupt halt.
This option is available with the Axial mode only. When the option is enabled (as it is by default), the drag will cause deceleration only. If instead the option is disabled, objects will be accelerated by the drag if their motion is pointing in the same direction as the drag force.
This has the same effect as described in the Gravity section above.
Example:
Suppose you want to simulate a soft ball being thrown at a wall. To accomplish this, you could use a drag field to bring the ball to an abrupt halt in the wall region, plus a gravity field to accelerate the ball towards the ground after it has hit the wall.
Although a Linear drag field would be able to halt the ball as it nears the wall, the field would in addition prevent the ball from accelerating towards the floor under gravity.
The ball would remain stuck to the wall.
The solution is to use the Axial field, which will exert drag in a defined direction only. By setting the direction of the Axial field force to the opposite direction of the balls initial motion, the drag will stop the ball as it nears the wall yet it will not oppose the downwards motion. The ball will be allowed to fall to the floor.
