Help with Collisions...

#1 There are a few ways of achieving this.

In all cases, you should call %character.setCollisionCallback(true); when creating the object.

This will tell the engine to execute function onCollisionCallback where your object is involved in a collision.

You simply need to write the function in your script and make it do whatever you want. The echo statement below is just to make sure that the function gets called properly and prints the defined string to the console.

mainCharacter.OnCollisionCallback(%this, %otherobject, %contactdetails)
{
echo(%this SPC "hit object" SPC %otherobject);
...
}

So here are the two methods

1 - Manually setting Velocity

When the collision occurs, you can call

%this.setLinearVelocity("0 0");
%this.setAngularVelocity("0");

The object will stop dead in its tracks and won't be sent spinning.

2 - Using sensors

After creating your CollisionShape, call

%character.setCollisionShapeIsSensor(0, true);

Where 0 is your shapeindex (if you have more than one collision shape on your object).

This will completely disable physics-based reactions on your object but the collisions will still be detected!

As in example 1, you can simply set the linear and angular velocities to 0 at this point.

#2 Thank-you. I saw the method setCollisionShapeIsSensor in the documentation for sceneObjects, but I thought that this would let the sceneObject pass right through the collision polygons. I'll give both solutions a try and let you know if they work.

#3 I'm still having the same issue. I notice that the velocity that it bounces back with is exactly opposite of the velocity that it hits the collision polygon's with. I'm thinking maybe I have not included something in my controls script.

Here is the full code for my character script, controls included...

function createCharacter()
{
    %character = new Sprite(mainCharacter);
    
    %character.SetBodyType( dynamic );

    %character.Position = "20 20";

    %character.Image = "RPGModule:test";

    %character.setCollisionCallback(true);

    %character.createPolygonBoxCollisionShape();

    %character.setFixedAngle( true );

    myScene.add(%character);
}

function mainCharacter::onCollision(%this, %sceneobject, %collisiondetails)
{
    %this.setLinearVelocity("0 0");  
    %this.setAngularVelocity("0");
}

function mainCharacter::Left(%this)
{
    %dir = Vector2Direction(270, 30);
    %this.applyLinearImpulse( %dir, "0 0");
}

function mainCharacter::LeftStop(%this)
{
    %dir = Vector2Direction(270, -30);
    %this.applyLinearImpulse( %dir, "0 0");
}

function mainCharacter::Right(%this)
{
    %dir = Vector2Direction(90, 30);
    %this.applyLinearImpulse( %dir, "0 0");
}

function mainCharacter::RightStop(%this)
{
    %dir = Vector2Direction(90, -30);
    %this.applyLinearImpulse( %dir, "0 0");
}

function mainCharacter::Up(%this)
{
    %dir = Vector2Direction(0, 30);
    %this.applyLinearImpulse( %dir, "0 0");
}

function mainCharacter::UpStop(%this)
{
    %dir = Vector2Direction(0, -30);
    %this.applyLinearImpulse( %dir, "0 0");
}

function mainCharacter::Down(%this)
{
    %dir = Vector2Direction(180, 30);
    %this.applyLinearImpulse( %dir, "0 0");
}

function mainCharacter::DownStop(%this)
{
    %dir = Vector2Direction(180, -30);
    %this.applyLinearImpulse( %dir, "0 0");
}

And here is my Input manager details...

function InputManager::Init_controls(%this)
{
    new ActionMap(characterControls);

    characterControls.bindCmd(keyboard, "a", "mainCharacter.Left();", "mainCharacter.LeftStop();");
    characterControls.bindCmd(keyboard, "w", "mainCharacter.Up();", "mainCharacter.UpStop();");
    characterControls.bindCmd(keyboard, "d", "mainCharacter.Right();", "mainCharacter.RightStop();");
    characterControls.bindCmd(keyboard, "s", "mainCharacter.Down();", "mainCharacter.DownStop();");

    characterControls.push();
}

#4 Oh, I think I just solved my problem!

I shouldn't be stopping my sceneObject by applying a reverse linear impulse, but should just use setLinearVelocity to "0 0".

#5 Adding an inverse Linear Impulse is great for slowing down but won't stop the object immeditately.

So are your saying the object now stops when colliding with other objects?

#6 Yes.

I changed all of my button up functions to set linear velocity to zero.

This is a good temporary fix, but I need to make it so that when the button is released only that directions linear velocity is set to zero.

I'm sure I just need to specify a direction using the method setLinearVelocity. I'll check out the documentation to see how to do that.

Thanks so much for your help. I think I have a better idea of how the physics work in the engine.

#7 My pleasure!

You can use LinearDamping to slow down the character.

I suggest reading the control section of the Getting Started Guide to get a real-life example of how to obtain directions from vectors.

Just scroll to the function PlayerShip::accelerate(%this).

Also, you can try setLinearVelocityPolar(, which takes an angle and speed instead of X,Y coordinates.

#8 Actually, scratch that, the methods setLinearVelocityX and setLinearVelocityY will work perfect.