[DarkGDK 2.0] ids auto selection , is it a bug?

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haliop

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Posted: 13th Jul 2012 04:11 Edited at: 13th Jul 2012 04:12

The new GDK comes with new feature where you dont have to assign Ids for objects or images etc..
it will find it for you if you assign -1 to the object id var or just leave it blank.

however , when i used such a system i used one of the following

finding empty id slot

+ Code Snippet

int FreeObject(void)
{
int t = 1;
while (dbIsObject(t) == 1)
{
t++;
}
return t;
}

this will cycle trough all objects from slot 1 to whatever slot is empty.

or the other way

+ Code Snippet

int FreeObjectCounter = 0;
int FreeObject(void)
{
FreeObjectCounter ++;
return FreeObjectCounter;
}

this a simplier way to achive the same goal will just increase the counter each time it is called and return a new and open id slot.

however
since DarkGDK 2.0 i started using the built in feature as mentioned at the top of this post, but something very strange is happening
it gives random numbers instead of increasing or open slots
one id can be 1 and the other can be 2304 and the third can be 5
i dont know why it is working like that i dont have the open source for it but should it do that or is that a bug?
cause if i want to use dbPickObject(MouseX,MouseY,startId,endId) it gets kinda messed up where the command cycle trough alot of ids that arent neccesery for it.

any suggestion how this system works?
maybe its a bug of somekind and mybe that is causing my games to crush sometimes..

mistrel? ..

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Hawkblood

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Posted: 13th Jul 2012 04:32

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Yes. I found it too. My count starts at 22 for some reason for camera,image,and fx, and 601 for objects.... Weird.

The fastest code is the code never written.

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Rudolpho

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Posted: 13th Jul 2012 13:59

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I believe it might be using something like:

+ Code Snippet

int findFreeID(int min = 1, int max = 65535) {
    static const int randomAttempts = 16;
    int rndRange = max - min, 
        id;
    for(int i = 0; i < randomAttempts; i++) {
        id = (rnd() % rndRange) + min;
        if(!dbIsObject(id))
            return id;
    }
    
    // Ok, we didn't find any random ID, let's try a linear search from here
    if(id >= (max / 2)) {
        for(int i = id; id >= min; id--)
            if(!dbIsObject(id))
                return id;
    } else {
        for(int i = id; id <= max; id++)
            if(!dbIsObject(id))
                return id;
    }
    
    // If we still haven't found a free ID we could try linearly searching in the other direction as well....
}

The idea is that, until you start having a large amount of ID's allocated (for bitmaps, cameras or lights it might not make a huge difference, but assuming objects and images which may (or may not) allow ID's up to 2^32 - 1 / 2) you are likely to pick a free ID at random in just a few tries.

"Why do programmers get Halloween and Christmas mixed up?"

+ Code Snippet

Because Oct(31) = Dec(25)

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Hawkblood

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Posted: 13th Jul 2012 14:26

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This can't be done with cameras. Cameras have to be sequential.

The fastest code is the code never written.

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Mistrel

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Posted: 13th Jul 2012 14:32 Edited at: 13th Jul 2012 14:34

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DarkGDK 2.0 handles ID allocation using a hashmap cache for speed (the IDs are cached, not the actual allocation). Because of this implementation, the order in which IDs are returned is undefined.

Currently there is special handling for dynamic cube maps (IDs 1-10) and memblocks (IDs 1-255); neither sequential. I can provide special functionality for cameras if you can demonstrate the problem in an example.

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Hawkblood

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Posted: 13th Jul 2012 14:45

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It's simple. If the cameras are not sequential, they don't appear correctly. This issue is a DBP issue, but it's not something to worry about. The only thing that needs to be addressed is the auto-assignment for cameras.

+ Code Snippet

int FindFreeCamera(void){
	int i;
	for (i=1;i<32;i++) if (dbIsCamera(i)==0) break;
	return i;
}
int Cam=dbCreateCamera(FindFreeCamera());

This works every time.

The fastest code is the code never written.

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Mistrel

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Posted: 13th Jul 2012 14:57

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What doesn't appear correctly? The cameras seem to exist just fine:

+ Code Snippet

sync on
sync
sync

make object cube 1,3
delete object 1
backdrop off

for i = 1 to 300
  make camera i
  print i;" ";camera exist (i)
next i

sync

wait key
end

Also, is there an upper-limit for cameras where things stop working such as 31, 32, 255..?

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Hawkblood

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Posted: 13th Jul 2012 15:38

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Yes, the camera exists, but the render is wrong. If you have camera0 (which is always there) and skip camera1 and create camera2, camera2 will render but won't render to texture--it will render to the screen over whatever camera0 is rendering. It seems that it renders to camera0's back buffer. If you have cam0 and cam1, cam1 will render to image (if you set it up). As I said, it's not non-sequential cameras that's the problem, it's that DGDK2.0 auto-assigns them non-sequentially. This is an easy fix (I think); at least we can work around it by assigning them manually.

The fastest code is the code never written.

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Dark GDK / [DarkGDK 2.0] ids auto selection , is it a bug?