The Physics – Background Movement allows you to dispose background elements in your world.

Objects with a background movement do not move by themselves (but they can be moved or rotated with Set position and Set angle actions). You can for example, create a static platform that rotates slowly : the character will be able to climb on it.

Collisions with background movement set as obstacles or platforms must be done with a “Collision with background” condition.

The background Movement is also great to create pivot objects in the world : just set the obstacle property to “None” and you will have a static object, that will not move if pushed by other objects, and you will be able to use it as a pivot point for joints.

The Properties

• Object
  • Friction
    This property defines how the object behaves when it is colliding with another object. A friction of 0 will make the object slide on the other object (like ice-skating). A friction of 100 will make it stop when it collides with another object (and will influence the other object).
  • Elasticity
    This property contains the elasticity factor of the object. Use a value of 0, and the object will stop as soon as it collides with another object. Use a value of 100, and the object will bounce, keeping the momentum of its movements. Intermediate values change the bouncing factor, and how the momentum is transfered while bouncing.
  • Obstacle
    This property defines the behavior of the object related to collision detection. It can have 3 values :
    • None
      The object will not generate any background collisions. You will though be able to detect the collisions of the other objects with it, with a simple “Collision with another object” condition. The option is great for creating static objects in the world.
    • Obstacle
      The object will behave like a backdrop object set as obstacle. Collisions with it will have to be detected with a “Collision with a backdrop” condition. Note that the “Collision with another object” condition will never be true when this property is set to obstacle.
    • Platform
      The object will behave like a backdrop object set as platform : the objects will be able to pass through it in the direction opposed to the gravity of the world. Collisions with it will have to be detected with a “Collision with a backdrop” condition. Note that the “Collision with another object” condition will never be true with this property set to platform.
• Joint
  Clickteam Fusion 2.5 allows you to automatically create a joint linking your object to another. This allows you to create cars with moving wheels, animated skeleton-based characters, flippers etc.
  • Type
    This property indicates which kind of joint to create. It can take the following values :
    • None
      No joint is created, the object is independant from any attach. This is the default value.
    • Revolute joint
      A revolute joint is created: the object will spin around its axis, and will be firmly linked to the other object. If this option is selected, two new properties appear :
      • Lower angle
        Enter in this property the minimum angle of the joint, in degrees. If the two values are equal, the joint will have a fixed angle. If the lower value is higher than the upper angle, the joint will have no angle limits.
      • Upper angle
        Enter in this property the maximum angle of the joint, in degrees.
    • Distance joint
      A distance joint is created : the object will stay at a fixed distance from the parent object, and will swing on its axis. Two new properties appear if this option is selected :
      • Frequency
        Enter in this property the resonance frequency of the joint, in Hz (number of vibrations per seconds). If a force is applied to the joint, the axis will start to resonate at this frequency.
      • Damping
        Enter in this property a damping value from 0 to 100, that will stop the axis from resonating.
    • Prismatic joint
      The object will be linked to the parent object by an invisible piston, and will only move on its axis. Two new properties appear when you select this option :
      • Lower limit
        Enter in this property the minimal distance between the two objects, in pixels. If this value is equal to the upper limit, the object will not be able to move on its axis. If this value is higher than the upper limit, the joint will not be limited.
      • Higher limit
        Enter in this property the maximum distance between the two objects, in pixels. The joint will be limited between the lower and the higher values.
  • Joint name
    Enter in this property a unique name for the joint. You will be able to access this joint and set its parameters by using this name with the Physics – Engine Joint actions.
  • Joint with
    Enter in this property the name of the object to link with. If no object with that name exists in the frame, then the joint is not created. If several objects with the same name exist, Clickteam Fusion 2.5 will choose the closest object to create the joint.
  • Anchor
    Defines where the joint is created.
    • From the hot-spot
      The joint is created at the hot-spot of the two objects (or the current object only for revolute joints).
    • From the action-point
      The joint is created at the action-point of the two objects (or the current object only for revolute joints).
• Advanced
  • Engine ID
    This property is designed to be used if you drop more than one Physics – Engine object in your frame. Enter the Engine ID value of the engine you want to use for this movement.
  • Collision shape
    This property defines the collision shape of the object, as seen in this page.
  • Auto-rotations
    This property defines how the object should be displayed, as seen in this page.
  • Smooth rotations
    This option has an effect in Windows applications only. If you check this option the image rendering will be much better when the object is rotated. Note: if your application is in Standard Display mode (non Direct3D) use this option carefully as it takes more processing time in this mode.

 The Actions

• Set elasticity
  Changes the elasticity factor of the object. Use a value of 0 and the objects colliding with the background object will stop instantly. A value of 100 will make it totally elastic : the other objects will bounce when colliding with it.
• Set friction
  Changes the friction parameter of the object. This value defines how the other objects behave when they are colliding with it. A friction of 0 will make the other objects slide on it (like ice-skating). A friction of 100 will make them stop and stick to it.