Player colliding with NPCs, but NPCs not with each other

[zewa666]

So I was wondering how, using collision groups, one could define that the player collides with npcs, but NPCs do not collide with each other. NPCs are added dynamically so the only way I could think of doing it now is:

• Player has collisionGroup player
• When first NPC appears it has also player
  • additionally a new group npc1
  • and the player is updated via setCollisionGroups to get npc1 as well
• For every other NPC do same as previous step but with npcN+1

which results in the player having the same collision groups with every individual NPC, but they only share the group with the player and not each other. It sounds a bit weird though having to create so many groups, so I was wondering whether there might be a better approach to this?

[Annoraaq]

That's an interesting question. I can't think of a different way of achieving it with the current features.

Maybe there is a way to better support this in GridEngine in the future. Do you have any ideas?

[zewa666]

I meant complexity in the perspective of the consumer (one less step to do), but certainly also runtime complexity. The later though is a question of how many NPCs one is going to have to be really noticable . also there might be different types of NPCs where A does collide with B (friendly vs enemy)

[zewa666]

another idea would be to define collision and nonCollision groups. say player char has player collision but friend nonCollision, now friendly NPCs could have friend nonCollision as well but enemies player as collision. nonCollision matches would negate collision effects. This way generation of new NPCs is would become trivial. the only open question is if both collision and nonCollision result in a match, which one wins :)

[Annoraaq]

A third idea would be to define which collision groups should collide with each other. Currently they collide with each other if they are the same. So {"group1" : ["group1"]}.

However, one could override this mapping. In the original example where NPCs should collide with the player but not with each other the following mapping would work:
{ "player" : ["player", "npc"], "npc": ["player"] }.

This way "player"s would collide with "npc"s but "npc"s only with "player"s.

GridEngine must assure that the relation stays symmetric.

[zewa666]

i think that would definitely work

[Annoraaq]

I created an issue for this so it does not get lost: #260