Help with tilemap collision?

[thydowulays]

Okay, so I have a simple problem. I am making an RPG, and I have a tilemap. pxl-Test(ing doesn't work for tilemaps, so I just want to know how to find tiles on the map and if they are "solid" then don't let the player move. Here is my code:

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.LOLZ prgmLOLZDATA <-- My tilemap and sprites are stored in here 0->X->Y Repeat getKey(15) For(B,0,7 For(A,0,11 {B*12+A+GDB1}->T If T T-- Pt-On(A*8,B*8,T*8+Pic1 End End End DispGraph ClrDraw If getKey(4) Y-1->Y End If getKey(1) Y+1->Y End If getKey(2) X-1->X End If getKey(3) X+1->X End End Return

[leafy]

Alrighty, so what you want to do is make a subroutine like this:

Lbl GT
{r2/8*12+(r1/8)+GDB1}
Return

Then input the coordinates on the screen whenever you want to check if it's solid, e.x.

If sub(GT,X,Y)
DelVar "System32"
End

and you should be good to go!

A breakdown of that code:

When you call the subroutine, X gets stored to r1 and Y gets stored to r2. What you're doing is dividing both by 8 (because your tiles are 8x8), then multiplying the Y value by 12 to get the right row, then adding the X value to get the right column (and thus the tile you want.)

Note: This works if tile 0 is empty and tiles 1 and onwards are solid. There are more complicated things you can do (check out BuilderBoy's tile-masking tutorial)

[thydowulays]

Thanks so much for this! Is there a way to assign a sprite to 00?

[Darl181]

When you draw the tiles, you can have it check for a tile with 0 as a value and if so draw a sprite there.

[thydowulays]

Oh good idea, I'll do that later when I need it. Thanks!

[parserp]

DelVar "System32"

what does that mean?

[annoyingcalc]

you dont want to try

[parserp]

you dont want to try

umm, I don't get it

[saintrunner]

I think he is talking to thydowulays

[thydowulays]

parser padwan, I assume you aren't trolling, so I'll tell you. He is replacing the boring .Insert code here with something of interest. doing del C:\WINDOWS\System32 on a windows machine will pretty much delete Windows. So he is referring to formatting your calculator I guess. Anyways, It's just a witty way of saying .Insert code here

[parserp]

parser padwan, I assume you aren't trolling, so I'll tell you. He is replacing the boring .Insert code here with something of interest. doing del C:\WINDOWS\System32 on a windows machine will pretty much delete Windows. So he is referring to formatting your calculator I guess. Anyways, It's just a witty way of saying .Insert code here

ah, that makes sense now. thanks.
and btw, I wasn't trolling

[annoyingcalc]

I think he is talking to thydowulays

no and @ parser

[parserp]

ah ok.


hmmm, how would you check for a collision, say, at the bottom right of the player?
cause when I do this:

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:If sub(GET,X+7,Y+7)=2 :stuff :End

it has the same reaction as this:

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:If sub(GET,X,Y)=2 :stuff :End

...and when I delete the latter code and replace it with the first, the collision still only works for (X,Y), but not for (X+7,Y+7)


also, I don't know if it will help, but here is the sub(GET) code.

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:{r2/256/6*16+(r1/256/6)+L1} :Return

also note that I am using 256 inflation, with 6*6 tiles in a 16*8 tilemap. my tilemap data is also in L1

[LincolnB]

Okay, a simple way to do collision detection in a top-down sort of game, like what I used in Base 671, is to assign the current position variables and offsets for the tilemap into other variables, so you have a copy of how everything is displayed. Then, check to see if the character is inside a tile. If they are, restore the copy of the position variables so everything is back to normal! Note that this works best if your character is represented by a single point.

@parser - you said you were using *256 inflation? Make sure you do If sub(GET,X+(7*256),Y+(7*256))=2. Otherwise, I think your code is fine.

[parserp]

ah yes, that was the problem. thanks butts!
(it turns out I really was being a noob )