physics_joint_distance_create(inst1, inst2, w_anchor1_x, w_anchor1_y, w_anchor2_x, w_anchor2_y, col)
| Argument | Description |
|---|---|
| inst1 | The first instance to connect with the joint |
| inst2 | The second instance to connect with the joint |
| w_anchor1_x | The first x coordinate for the joint, within the game world |
| w_anchor1_y | The first y coordinate for the joint, within the game world |
| w_anchor2_x | The second x coordinate for the joint, within the game world |
| w_anchor2_y | the second y coordinate for the joint, within the game world |
| col | Whether the two instances can collide (true) or not (false) |
Returns: Index of the joint
One of the simplest joint is a distance joint which says that
the distance between two points on two instances must be constant.
When you specify a distance joint the two instances should already
be created and have a fixture assigned, then you define the two
anchor points in room coordinates. The first anchor point is
connected to instance 1, the second anchor point is connected to
instance 2 and the distance between these points imply the length
of the distance constrain. The image below shows how this
works:
As you can see, the anchor points are specified as room
coordinates so care must be taken when defining them, especially if
the instances are being created at the same time as the joints
rather than being placed in the room through the room editor. You
should also realise that the joints are created independently of
the size of the sprite of the instances or the fixtures they have
attached. So, if you create a distance joint somewhere other than
the origin of the instance, it is still valid and will constrain
the two instances relative to the position at which it was created.
If you set the "col" value to true then the two instances
can interact and collide with each other but only if they
have collision events, however if it is set to false, they
will not collide no matter what.
var mainFixture, o_id;
mainFixture = physics_fixture_create();
physics_fixture_set_circle_shape(mainFixture,
sprite_get_width(sprite_index) / 2);
o_id=instance_create(x+300, y, obj_Rudder);
physics_fixture_bind(mainFixture, id);
physics_fixture_bind(mainFixture, o_id);
physics_joint_distance_create(id, o_id, x + 50, y, o_id.x - 50,
o_id.y, 0);
physics_fixture_delete(mainFixture);
The above code creates and defines a new fixture and then creates an instance of "obj_Rudder". The fixture is then assigned to the instance that is running the code as well as the newly created one and a joint is created between them. Finally the fixture is deleted as it is no longer needed.