How to cancel collision force

Getting Started Newbie Questions
#1

I was wondering if there is any way to stop a collision from producing a force on a dynamic object.

For instance, if a moving ship collides with a still ship, the still ship will not move when hit.

#2

No.  Make the object you want to NOT move a “kinematic” body type.

#3

Note.  If you can’t use a kinematic body, you might try this:
 

  1. At time of collision, do this to the object that was hit and must not move:

    obj:setLinearVelocity(0,0) obj.angularVelocity = 0

  2. Then set a timer to re-stop the object response

    timer.performWidthDelay( 1, function() obj:setLinearVelocity(0,0) obj.angularVelocity = 0 end )

This may not work consistently however. i.e. There may still be motion/response.

Additionally, this will interfere with any other code you may have that is moving that object.

#4

Another way to ‘minimize’ collision responses is to:
 

  1. Make the hitting object have a very low mass (via the density value):

    physics.addBody( bullet, { density = 0.01 …

  2. Make the collidee (the object that is hit and you don’t want to move) have  very high mass (via the density value):

    physics.addBody( ship, { density = 1e6, …

#5

Thank you, I will implement these and see how they go.

#6

H sdktester15,

try set .isBodyActive to false for object using timer with 1ms delay :

timer.performWidthDelay( 1,    function()       ship.isBodyActive = false    end )

From Corona documentation

Gotchas

If this property is set to false on an active object currently in collision state with another, a collision with a phase of “ended” will immediately be triggered. Likewise, if this property is set to true on an inactive object currently in collision state with another, a collision with a phase of “began” will immediately be triggered.

Have a nice day:)

ldurniat

#7

Thanks, I’ve discovered a bit of a workaround for this in my case. 

But, this is good to know in case I need it later.

#8

No.  Make the object you want to NOT move a “kinematic” body type.

#9

Note.  If you can’t use a kinematic body, you might try this:
 

  1. At time of collision, do this to the object that was hit and must not move:

    obj:setLinearVelocity(0,0) obj.angularVelocity = 0

  2. Then set a timer to re-stop the object response

    timer.performWidthDelay( 1, function() obj:setLinearVelocity(0,0) obj.angularVelocity = 0 end )

This may not work consistently however. i.e. There may still be motion/response.

Additionally, this will interfere with any other code you may have that is moving that object.

#10

Another way to ‘minimize’ collision responses is to:
 

  1. Make the hitting object have a very low mass (via the density value):

    physics.addBody( bullet, { density = 0.01 …

  2. Make the collidee (the object that is hit and you don’t want to move) have  very high mass (via the density value):

    physics.addBody( ship, { density = 1e6, …

#11

Thank you, I will implement these and see how they go.

#12

H sdktester15,

try set .isBodyActive to false for object using timer with 1ms delay :

timer.performWidthDelay( 1,    function()       ship.isBodyActive = false    end )

From Corona documentation

Gotchas

If this property is set to false on an active object currently in collision state with another, a collision with a phase of “ended” will immediately be triggered. Likewise, if this property is set to true on an inactive object currently in collision state with another, a collision with a phase of “began” will immediately be triggered.

Have a nice day:)

ldurniat

#13

Thanks, I’ve discovered a bit of a workaround for this in my case. 

But, this is good to know in case I need it later.