Trying to determine if a location is empty.

[Argh]

I'm trying to write an expression that checks a given location X,Z for the presence of any Units. If there aren't any Units around, then it should return nil. However, I am having trouble getting it to return a value that is useful.

Here's the code:

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                    local Empty = Spring.GetUnitsInSphere(X, 0, Z, 200)
					
					if Empty[1] == nil then Do Stuff end

I don't get it. Shouldn't the first index of Empty return non-nil if any Units are within that sphere? Or am I doing something wrong here?

[Kloot]

Spring.GetUnitsInSphere

( number x, number y, number z, number radius [,number teamID] )
-> nil | unitTable = { [1] = number unitID, etc... }

This...

Code: Select all

if Empty[1] == nil

... will therefore fail if the sphere contains no units, and
always evaluate to false if it does.

[KDR_11k]

Also wouldn't GetGroundBlocking be more effective?

[TheFatController]

GetPositionLosState is pretty cool if it's what you need, it returns three booleans for if the point can be seen by any units. I think something like LOS(or)RADAR, Radar, LOS for an x,y,z location

[Argh]

This didn't work, took code down.

[Argh]

Looks like this is a failure, too Nevermind...

[Argh]

Ok, this code seems to find a collision every time:

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                	Empty = Spring.GetUnitsInRectangle(MinX,MinZ,MaxX,MaxZ)
                	Empty2 = Empty[1]                	
                	if Empty ~= nil then
                	if Empty2 ~= nil then CanPlace = 0 end
					if Empty2 == nil then CanPlace = 1 end
					end

[Argh]

Success, at last. Arbitrarily-placed Units, of any Team, can now be placed within World Builder, during the first frame of simulation, and will not get procedural elements placed over them. Should help get this to be used by mappers, because they can place any specialized objects they desire, with no worries that they'll get visually obliterated or cause bad gameplay.

Lurker, this does not obviate my desire to have a grid solver, however- I still want something to help place sub-objects within a given range X,Z, and this procedure's an all-or-nothing deal, not very sophisticated.

Lastly, yes, this means that I can finally send the demo out, I just want to make a bit more content first. <starts making stuff>

[lurker]

Yeah. I haven't had any time the last couple days, but it's becoming the weekend now. I'm working on it / trying to stop introducing algorithm flaws. It would probably help me make the api to have a copy of the demo.

[KDR_11k]

For reference, this is how Fibre handles building placement:

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		local ok, f = Spring.TestBuildOrder(-cmd, c.x, c.y, c.z, c.heading)
		if ok == 2 and not f then

[Argh]

Cool, thanks for sharing that. I'll try that and compare the results, maybe it'll be more flexible than what I'm doing, which is not terribly flexible, and allow me to do some more randomization.

[Argh]

Um, KDR, how does Spring.TestBuildOrder know the size of the Unit it's trying to build? Using a point won't do at all.

[trepan]

Straight from the wiki, you don't try very hard...

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Spring.TestBuildOrder

 ( number unitDefID, number x, number y, number z, number facing)
   -> number blocking [,number featureID]

 blocking can be:
   0 - blocked
   1 - mobile unit in the way
   2 - free  (or if featureID is != 0 then with a blocking feature that can be reclaimed)

[FLOZi]

As much as I often disagree with Argh's methods, 9 times out of 10 asking someone in the know is far more productive than looking thorugh the wiki (Very unfortunately)

[Argh]

@KDR: I've tested your method, and after some trouble, got it working, thanks to your example code in Fibre. However, it's quite a bit slower than what I'm doing. On the other hand, your method is more generally useful by far- mine's very crude, and requires strict controls to work propertly, but is speedy.

@FLOZi: Asking for help, on the Forum area devoted to the second major programming language game designers for Spring are supposed to learn, seems entirely appropriate to me. Everybody learns. I do not care if people don't like it, frankly.

[KDR_11k]

As much as I often disagree with Argh's methods, 9 times out of 10 asking someone in the know is far more productive than looking thorugh the wiki (Very unfortunately)

Meh, if you're just looking for a callout the Wiki has a nice list that's often sufficient.