Physics Joints - Learn SpriteBuilder for iOS Game Development - page 301

Now open the TriggerOnce.ccb , and repeat the process for any additional triggers you
may have created, such as the TriggerForever.ccb . Select the CCNodeColor node to edit
its Item Physics properties.
Enter trigger in the Categories field and player in the Masks field. This ensures that the
player can collide with triggers, since the player already has trigger in its collision mask
and the trigger now has the player in its collision mask as well. Collisions occur only
when both participants have each other's category in their Masks field, or when the Masks
field is empty for at least one participant.
The borders are edited in the same way, except you'll find multiple border CCB files un-
der Prefabs/Borders , starting with Border1.ccb . You need to open each border CCB and
in the its root node's Categories field enter border and in its Masks field enter player . This
ensures that all border sprites continue to be impenetrable collisions for the player.
Finally, and this is where it gets tedious, you need to edit each physics-enabled node in
both Chain.ccb and Rope.ccb to update their categories and masks. In each physics-en-
abled node's Categories field, enter obstacle , and in its Masks field enter player, obstacle
to make the chain or rope collide with the player as well as other chains and ropes. Again,
note that the items must be comma-separated to create separate labels, as you saw on the
right side of Figure 9-15 .
Tip You may want to enter the Masks text once, ensure that it is correct, and
then select the labels either by clicking in the field and pressing Cmd+A or by
using text selection. To use text selection, drag the mouse from one end of the
text to the other. The labels are drawn in a dark blue color when selected. You
can then press Cmd+C to copy and Cmd+V to paste the labels in another node's
Masks field. That way, you can reduce the risk of creating a typo.
If you forget to edit one chain or rope element's categories or masks, that element might
still collide with the player. To ensure correctness, verify the categories and masks once
you are done editing.
Select the first node in the Timeline; this will most likely be the static hook node. Look at
its Item Physics tab, and confirm that the Categories and Masks are correct. Now press the
down arrow key to select the next node in the Timeline. By repeatedly pressing the down
arrow key, you can quickly verify the collision and other settings of a series of nodes. It
definitely beats clicking each node with the mouse.
Good. Now that all the physics nodes in Chain.ccb and Rope.ccb have their categories and
masks set, you can give this a try.