Collision with particular object?

[Andy Gilbert]

Hi, ive done a search but cant seem to find the answer.

 

What is the current way using lua to detect a collsion with a particular object?

 

Can i determind the collsion using the objects name somwhow?

 

Thanks

Andy

[Rick]

You can use the objects name with something like: entity:GetKeyValue("name"). I would however say this isn't the best way as it's sort of bastardizing the name field and isn't as flexible as making another key specifically for "type" or something like that. This would be much easier and better with multiple scripts per entity ( ) but you can do it with the same script. Just expose a type string variable to objects and then check the type and determine what to do from there. entity:GetKeyValue("type").

 

One thing I did with this is to identify the "floor" vs walls an everything else for the pathfinding. If I have a game where the player moves where I click, then if I click on a wall the player would try to move there. To prevent this when there were multiple scripts per entity I made a Lua script specifically just to expose a Type string variable and set it's value to "floor" and check that when I do the picking and only try to move if it's of type "floor". You can do the same with 1 script but you have to put this code into each script, duplicating the effort.

[beo6]

Can't you just check for the normal in the collision to check if it is a wall or the floor?

 

that way you would not need to add a script to the CSG objects which would disable the internal optimization for it.

 

Another way could be to check the collisiontype.

[Rick]

I'd have to test the normal collision to see if that works. I felt the script way was the most flexible but of course requires more work to be done.

 

 

You'd still have to define the collision type as I don't think there is a default wall/floor in LE. So you'd need a way to define that and that would be in a script right? Then you are back to doing it in a script anyway.

[Andy Gilbert]

Sorry to be a pain, but is there some example script of how this is actually achived or what functions to use?

 

Its a simple test, between one object and another.

 

Thanks

Andy

[beo6]

@Rick you can define the collision type in the editor without attaching any script.

 

However there is of course no wall/floor collsiontype. Only Scene

[josk]

If you have a moving object and a stationary object.

Call your moving object gobbo in the Scene editor.

attach the following script to the stationary object.

function Script:Collision(entity, position, normal, speed)
being = entity:GetKeyValue("name")
if being == "gobbo" then self.entity:Hide() end
end

[josk]

@Rick

You can do the same with 1 script but you have to put this code into each script, duplicating the effort.

unless I have misunderstood you, If you use require you don't need to duplicate code, its kind of like an entity having mulitple scripts.

[Rick]

@beo6

However there is of course no wall/floor collsiontype. Only Scene

 

Yeah, that's what I was implying that in this instance being able to assign a collision type via the editor won't work to tell between wall/floor so that suggestion is off the table. Unless Josh gave us a way to add our own collision types that get exposed in the editor, which would be cool.

 

 

@josk

 

You can do a "require" to expose the field for a key/value but you need to actually set this to the entity. Which you would have to do in the Start() function of each script, which means you'd have to put code to set the key into each script. It may only be 1 line, but, and no offense to Andy as he's more of an art guy, people like Andy would benefit the most from this system and they don't know this stuff all that well, and in all honesty I hate code duplication so I wouldn't even like having to repeat this code in every script I need this functionality.

 

In the script you "require" there is no way to automatically assign the key/value that the user put into the editor to the entity. With multiple scripts we put that code inside it's own Script:Start() so it's done automatically and all the user has to do is attach the script and set the properties in the editor. No coding needed.

 

I actually made a request that setting/modifying entity keys for entities should be automatically included into the editor/engine which would help solve issues like this. I figured since key/value pairs are built into the engine the editor should support that functionality out of the box. Sounds reasonable to me

[AggrorJorn]

When you use require, are properties being created?

[Rick]

I haven't tested, but I would "think" that they are created, but maybe they don't which makes it even worse . However you'd still need to set keys to the entity in question from the properties in the Script:Start() function so :-/ .

 

 

[EDIT]

I couldn't get it to work. I added to your FG_Button.lua at the top, require "Scripts/Cameras/3rdPersonFollow.lua", and it gave no errors but no target property showed up like the 3rdPersonFollow.lua file has.

 

These properties are all LE "magic" and I'm guessing Josh's code that creates the properties doesn't look at nested files.

[josk]

After playing around I think I understand, basically though if we could add custom collision types under the Physics tab that would help.

[Andy Gilbert]

Hi, i seem to have this wokrnig great using

 

function Script:Collision(entity, position, normal, speed)
being = entity:GetKeyValue("name")
if being == "gobbo" then self.entity:Hide() end
end

 

But, what ive realised i want is to be able to detect collsion without collsion actually happeneing. As in, i have an object that moves and when it hits the "other" object i want to detect it touching it, but not actually stop and collide with it, (go through it!) Ive tryed make the collsion type to none, which makes the object no collide, but also make the collisionhook not work?

 

How could i do this?

 

Thanks

Andy

[Marleys Ghost]

Have you tried collision type trigger?

[Andy Gilbert]

I have now, and the object goes through but no collision callback is called?

 

Andy

[josk]

Have you unchecked navmesh. also on the stationary object I have collision type as Prop with no mass.

[Andy Gilbert]

Hi Josk, do you mean Nav obstacle? If so then that is unchecked. The collsion works fine, but like i said above i want to be able to go THROUGH the object but still pick up the collision hook.

 

I also have the static object as Prop, no mass.

 

Setting type as Trigger would do the trick IF is registered the collision callback, but it doesnt.

 

Thanks

Andy

[josk]

On my map my character passes through, still picks up the collision. i have the stationary object change colour when collision occurs.

[beo6]

If you enable "Show Physics" in the Editor and you see a collision box around that model the collision should work.

[josk]

Just had a look, if my character is a box built in the editor it stops, if its a model from an external source it goes through.

 

Set it to collision trigger it works. Basic code in the payer folder but working example.

[Andy Gilbert]

Hmm there must be something going on then, as i still cant get the collision to register, the object is very simple so ive ceated a polymesh from it and loaded that in, when "show Physics" is enable it fits great, set to trigger and the object goes though, but no collision is registered?

 

Andy

[Andy Gilbert]

Seems like ive done it, to get it to trigger i had to increase the physics box size. Maybe just doesnt like it being to small.

 

Thanks

Andy

[Rick]

If it's very small you might have to check that sweeping collision checkbox.