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Scripting 05 - Joints testbeds

A smaller forum with a few tutorials how to get started with the ScriptAPI.
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Gurt
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Scripting 05 - Joints testbeds

Post by Gurt » Thu Mar 17, 2016 9:20 pm

Scripting 05 - Joints

Scripting in SFD assumes you have a fair knowledge of C#. You should be able to declare variables, write your own functions and classes, you should know about inheritance and derived classes and know how to cast objects.

In the following scripts I will show how to create some different joints through script.

Distance Joint

You can try this script in an empty map. Just copy-paste it into the script window and test run the map.
// DISTANCE JOINT TEST
public void OnStartup()
{
        // Create ground
	CreateGround();
	
	// Create two crates - crateA above the ground and the crateB underneath
	IObject crateA = Game.CreateObject("Crate00", new Vector2(20f, 0f), 0f);
	IObject crateB = Game.CreateObject("Crate00", new Vector2(20f, -60f), 0f);
	
	// Create a distanceJoint which will connect to crateA
	IObjectDistanceJoint distanceJoint = (IObjectDistanceJoint)Game.CreateObject("DistanceJoint");
	distanceJoint.SetWorldPosition(crateA.GetWorldPosition() - new Vector2(0f, 8f));
	distanceJoint.SetTargetObject(crateA);
	
	// Create a targetObjectJoint which will connect to crateB
	IObjectTargetObjectJoint targetObjectJoint = (IObjectTargetObjectJoint)Game.CreateObject("TargetObjectJoint");
	targetObjectJoint.SetWorldPosition(crateB.GetWorldPosition() + new Vector2(0f, 8f));
	targetObjectJoint.SetTargetObject(crateB);
	
	// Connect the distanceJoint and the targetObjectJoint together
	distanceJoint.SetTargetObjectJoint(targetObjectJoint);
	
	// Set line visual and type of joint
	distanceJoint.SetLineVisual(LineVisual.DJWire);
	distanceJoint.SetLengthType(DistanceJointLengthType.Elastic); // NOTE: Elastic means the distanceJoint can shrink (but not grow)
	
	// Set some initial velocity to crateB to make a pendulum
	crateB.SetLinearVelocity(new Vector2(5f, 0f));
}

// Create some ground under the 0,0 coordinate of the world
private void CreateGround()
{
	IObject ground = Game.CreateObject("Concrete07B", new Vector2(8f*(-4.5f), 8f*(-1.5f)), 0f);
	Point sizeFactor = new Point(10, 1);
	ground.SetSizeFactor(sizeFactor);
}

Weld Joint

You can try this script in an empty map. Just copy-paste it into the script window and test run the map.
// WELD JOINT TEST
public void OnStartup()
{
        // Create ground
	CreateGround();
	
	// Create some crates in a square-like pattern
	IObject crateA = Game.CreateObject("Crate00", new Vector2(20f, 40f), 0f);
	IObject crateB = Game.CreateObject("Crate00", new Vector2(20f, 0f), 0f);
	IObject crateC = Game.CreateObject("Crate00", new Vector2(-20f, 40f), 0f);
	IObject crateD = Game.CreateObject("Crate00", new Vector2(-20f, 0f), 0f);
	
	// Create WeldJoint
	IObjectWeldJoint weldJoint = (IObjectWeldJoint)Game.CreateObject("WeldJoint");
	
	// SetTargetObjects on the weldJoint to weld them together
	weldJoint.SetTargetObjects(new IObject[] { crateA, crateB, crateC, crateD });
	
	// NOTE: You can also add and remove a single object to the weldJoint with weldJoint.AddTargetObject(IObject) and weldJoint.RemoveTargetObject(IObject)
	
	// NOTE: Moving an object that's welded to other objects is NOT RECOMMENDED as the box2D will do some average positioning when resolving the weld-joint.
	// crateA.SetWorldPosition(new Vector2(100f, 100f)); // This will not work as intended
	// Instead use the alternative SetWorldPosition that takes a second parameter updateConnectedObjects
	// crateA.SetWorldPosition(new Vector2(100f, 100f), true); // This will work as intended and move all welded objects relatively crateA
}


// Create some ground under the 0,0 coordinate of the world
private void CreateGround()
{
	IObject ground = Game.CreateObject("Concrete07B", new Vector2(8f*(-4.5f), 8f*(-1.5f)), 0f);
	Point sizeFactor = new Point(10, 1);
	ground.SetSizeFactor(sizeFactor);
}

Elevator Attachment Joint

You can try this script in an empty map. Just copy-paste it into the script window and test run the map.
// ELEVATOR ATTACHMENT JOINT TEST
public void OnStartup()
{
	// Create ground
	CreateGround();
	
	// Create two elevatorPathJoints and connect them to each other
	IObjectElevatorPathJoint pathA = (IObjectElevatorPathJoint)Game.CreateObject("ElevatorPathJoint", new Vector2(8f*(-3.5f), 8f*(-0.5f)), 0f);
	IObjectElevatorPathJoint pathB = (IObjectElevatorPathJoint)Game.CreateObject("ElevatorPathJoint", new Vector2(8f*(-3.5f), 8f*(8.5f)), 0f);
	pathA.SetNextPathJoint(pathB);
	pathB.SetNextPathJoint(pathA);
	pathA.SetLineVisual(LineVisual.DJRope);
	
	// Create the elevator joint that will do all the work
	IObjectElevatorAttachmentJoint elevatorJoint = (IObjectElevatorAttachmentJoint)Game.CreateObject("ElevatorAttachmentJoint");
	elevatorJoint.SetWorldPosition(pathA.GetWorldPosition());
	
	// Create the lift player can stand on
	IObject lift = Game.CreateObject("Lift00A");
	lift.SetWorldPosition(pathA.GetWorldPosition());
	
	// Connect the elevatorJoint and the lift
	elevatorJoint.SetTargetObject(lift);
	
	// Connect the elevatorJoint to the path
	elevatorJoint.SetElevatorPathJoint(pathA);
	
	// NOTE: The elevator musn't overlap or clip anything or it might get stuck! 
	// You can not alter collision between objects as of Pre-Alpha 1.7.4 as the AlterCollisionTile is not yet implemented for the ScriptAPI.
}

// Create some ground under the 0,0 coordinate of the world
private void CreateGround()
{
	IObject ground = Game.CreateObject("Concrete07B", new Vector2(8f*(-4.5f), 8f*(-1.5f)), 0f);
	Point sizeFactor = new Point(10, 1);
	ground.SetSizeFactor(sizeFactor);
}

Pull Joint

You can try this script in an empty map. Just copy-paste it into the script window and test run the map.
// PULL JOINT TEST
public void OnStartup()
{
	// Create ground
	CreateGround();
	
	// Create two wheels to connect with a pull joint
	IObject wheelA = Game.CreateObject("TruckWheel", new Vector2(10f, 10f));
	IObject wheelB = Game.CreateObject("TruckWheel", new Vector2(10f, -20f));
	
	// Create the pullJoint for wheelA
	IObjectPullJoint pullJoint = (IObjectPullJoint)Game.CreateObject("PullJoint");
	pullJoint.SetWorldPosition(wheelA.GetWorldPosition());
	
	// Create the targetObjectJoint for wheelB
	IObjectTargetObjectJoint targetObjectJoint = (IObjectTargetObjectJoint)Game.CreateObject("TargetObjectJoint");
	targetObjectJoint.SetWorldPosition(wheelB.GetWorldPosition());
	
	// Connect targetObjectJoint to wheelB
	targetObjectJoint.SetTargetObject(wheelB);
	
	// Connect pullJoint to wheelA and targetObjectJoint (which is connected to wheelB)
	pullJoint.SetTargetObject(wheelA);	
	pullJoint.SetTargetObjectJoint(targetObjectJoint);
	
	// Set LineVisual
	pullJoint.SetLineVisual(LineVisual.DJRope);
	
	// Set forces for the pullJoint
	pullJoint.SetForce(0.6f);
	pullJoint.SetForcePerDistance(0.2f);
}

// Create some ground under the 0,0 coordinate of the world
private void CreateGround()
{
	IObject ground = Game.CreateObject("Concrete07B", new Vector2(8f*(-4.5f), 8f*(-1.5f)), 0f);
	Point sizeFactor = new Point(10, 1);
	ground.SetSizeFactor(sizeFactor);
}
Rail Joint

You can try this script in an empty map. Just copy-paste it into the script window and test run the map.
// RAIL JOINT TEST
public void OnStartup()
{
	// Create ground
	CreateGround();
	
	// Create railJoint
	IObjectRailJoint railJoint = (IObjectRailJoint)Game.CreateObject("RailJoint", new Vector2(-40f, 20f), 0f);
	
	// Create targetObjectJoint (the end of the railJoint)
	IObjectTargetObjectJoint railJointTargetObjectJoint = (IObjectTargetObjectJoint)Game.CreateObject("TargetObjectJoint", new Vector2(40f, 20f), 0f);
		
	// Connect the railJoint to the targetObjectJoint
	railJoint.SetTargetObjectJoint(railJointTargetObjectJoint);
	
	// Enable limits on the rail
	railJoint.SetLimitEnabled(true);
	
	// Create railAttachmentJoint
	IObjectRailAttachmentJoint railAttachmentJoint = (IObjectRailAttachmentJoint)Game.CreateObject("RailAttachmentJoint");
	railAttachmentJoint.SetWorldPosition(railJoint.GetWorldPosition());
	
	// Create a pulley
	IObject pulleyObject = Game.CreateObject("Pulley01");
	pulleyObject.SetWorldPosition(railJoint.GetWorldPosition());
	
	// Connect railAttachmentJoint to the pulley and the railJoint
	railAttachmentJoint.SetTargetObject(pulleyObject);
	railAttachmentJoint.SetRailJoint(railJoint);
	
	// Set some velocity at startup
	pulleyObject.SetLinearVelocity(new Vector2(1f, 0f));
}

// Create some ground under the 0,0 coordinate of the world
private void CreateGround()
{
	IObject ground = Game.CreateObject("Concrete07B", new Vector2(8f*(-4.5f), 8f*(-1.5f)), 0f);
	Point sizeFactor = new Point(10, 1);
	ground.SetSizeFactor(sizeFactor);
}
Pulley Joint

You can try this script in an empty map. Just copy-paste it into the script window and test run the map.
// PULLEY JOINT TEST
public void OnStartup()
{
	// Create ground
	CreateGround();

	// Create two crates underneath ground
	IObject crateA = Game.CreateObject("Crate00", new Vector2(-20f, -60f));
	IObject crateB = Game.CreateObject("Crate00", new Vector2(20f, -60f));
	
	// Create pulleyJoint above crateA
	IObjectPulleyJoint pulleyJoint = (IObjectPulleyJoint)Game.CreateObject("PulleyJoint", new Vector2(-20f, 30f));
	
	// Create pulleyEndJoint above crateB
	IObjectPulleyEndJoint pulleyEndJoint = (IObjectPulleyEndJoint)Game.CreateObject("PulleyEndJoint", new Vector2(20f, 30f));
	
	// Create targetObjectJoints for both crates
	IObjectTargetObjectJoint targetObjectJointCrateA = (IObjectTargetObjectJoint)Game.CreateObject("TargetObjectJoint", crateA.GetWorldPosition());
	IObjectTargetObjectJoint targetObjectJointCrateB = (IObjectTargetObjectJoint)Game.CreateObject("TargetObjectJoint", crateB.GetWorldPosition());
	targetObjectJointCrateA.SetTargetObject(crateA);
	targetObjectJointCrateB.SetTargetObject(crateB);
	
	// Connect pulleyJoint with crateA (targetObjectJointCrateA)
	pulleyJoint.SetTargetObjectJoint(targetObjectJointCrateA);
	
	// Connect pulleyEndJoint with crateB (targetObjectJointCrateB)
	pulleyEndJoint.SetTargetObjectJoint(targetObjectJointCrateB);
	
	// Connect pulleyJoint with pulleyEndJoint
	pulleyJoint.SetPulleyEndJoint(pulleyEndJoint);
	
	// Set LineVisual
	pulleyJoint.SetLineVisual(LineVisual.DJRope);
	
	// Set some initial velocity to crateA and crateB
	crateA.SetLinearVelocity(new Vector2(1f, 0.2f));
	crateB.SetLinearVelocity(new Vector2(-0.5f, -0.2f));
}

// Create some ground under the 0,0 coordinate of the world
private void CreateGround()
{
	IObject ground = Game.CreateObject("Concrete07B", new Vector2(8f*(-4.5f), 8f*(-1.5f)), 0f);
	Point sizeFactor = new Point(10, 1);
	ground.SetSizeFactor(sizeFactor);
}
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Gurt

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