The Physics – Race Car Movement makes your object move like a race-car seen from above. You can turn the object with the left and right keys, accelerate with the up key, and slow down with the down key. It is the only physical movement that is not subject to gravity : the object will float in the world whatever the value of the gravity of the world.

The Properties

• Movement
  • Initial direction
    Choose the direction at which the object will be created. If you select more than one direction, the final direction is chosen at random when the object is created.
  • Rotation speed
    This property contains the speed at which the object rotates when you press the left or right key. Choose a value of zero and your object will stay in the initial diection forever.
  • Speed
    This property contains the maximum speed of the object, when it reaches full speed.
  • Acceleration
    This property contains the acceleration factor of the object. A higher value means that the object will go from static to full speed in the minimum amount of time.
  • Deceleration
    This property contains the deceleration factor of the object. When you press the down arrow, the object will slow down. The higher the value of this property, the faster the object will come back to a zero speed.
  • Allow reverse
    Check this property and your object will go in reverse direction if you maintain the down key pressed. If unchecked, the object will stop if you keep the key down.
• Object
  • Density
    This property contains the density of the object, a number from 0 to 100. A dense object will be heavier, and therefore more difficult to move when colliding with other objects. The mass of the object is calculated by the engine from the surface of the object and from the density.
  • 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 movement. Intermediate values change the bouncing factor, and how the momentum is transfered while bouncing.
• 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

• Stop
  Stops the object. If the stop action is called within a collision with another object, the other object will be pushed. If the action is called out of a collision context, the speed of the object is set to zero (but the gravity continues its action, and the object will start to fall again).
• Set speed
  Changes the speed of the object. The object will start moving in the direction it is currently facing.
• Set acceleration
  Changes the acceleration factor of the object. The value has the same meaning as the “Acceleration” property.
• Set deceleration
  Changes the deceleration factor of the object. The value has the same meaning as the “Deceleration” property.
• Set rotating speed
  Changes the speed at which the object rotates when you press the left or right keys
• Physics
  • Set elasticity
    Changes the elasticity factor of the object. Use a value of 0 and your object will stop instantly when colliding with other objects. A value of 100 will make your object totally elastic : it will bounce when colliding with other objects or backgrounds.
  • Set friction
    Changes the friction parameter of the object. This value 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).
  • Apply impulse
    This action applies a brief force to the object in the given direction, resulting in the object moving in this direction, faster or slower depending on the object’s mass. Parameters: strength of the force to apply, and direction in degrees.
  • Apply force
    This action applies a constant force to the object : once started, the force will be applied at every loop of the game, until a “stop force” action is executed. Parameters: strength of the force and its direction in degrees.
  • Stop force
    Stops a force that has been applied to the object. The object will continue to move at its current speed and direction.
  • Set linear velocity
    Sets the instant velocity of the object. The object will start moving in the given direction, whatever its mass, size or density. Parameters: speed of the movement, a value from 0 to 250, and direction in degrees.