Coordinate inaccuracy and confusion

-Ramirez- · #1 09-29-2003, 05:46 AM

Ok, I've been rather reluctant to make any new threads on the forums, seeing as how most of them end up as "flame wars" or something else with a lot of insults, but nonetheless, I'm posting now.

First off, I've noticed that the gserver and NPC Server both don't send EXACT player/NPC coordinates. For example, an NPC could be on 30,40.599999, and the player would receive the coordinate 30,40.5. It truncates everything after the first digit following the decimal. This can cause problems with NPCs that need to be very accurate on their locations. Has anyone else noticed this happening?

Second... why do players/NPCs EVER end up on coordinates that aren't evenly divisible by 0.0625? That has eluded me for quite a while now. All coordinates should be evenly divisible by 0.0625, as that's 1 pixel in Graal coordinate terms. You can't exactly go smaller than a pixel...

I wanted to make sure I wasn't crazy before posting in the bugs section about this, that's why I posted it here. Feel free to move it, although it's not like you need my permission to do so. :P

Kaimetsu · #2 09-29-2003, 06:10 AM

Quote:

Originally posted by -Ramirez-
Second... why do players/NPCs EVER end up on coordinates that aren't evenly divisible by 0.0625? That has eluded me for quite a while now. All coordinates should be evenly divisible by 0.0625, as that's 1 pixel in Graal coordinate terms. You can't exactly go smaller than a pixel...

There is a reason, though it may not be immediately obvious. I'll see if anybody can guess ^_^

-Ramirez- · #3 09-29-2003, 06:17 AM

Quote:

Originally posted by Kaimetsu
There is a reason, though it may not be immediately obvious. I'll see if anybody can guess ^_^

Does it have anything to do with Graal's internal movement system?

Loriel · #4 09-29-2003, 07:37 AM

I blame Stefan's scary way to calculate the movement that happens if you walk against an edge and thus get pushed to the side.

-Ramirez- · #5 09-29-2003, 08:20 AM

Quote:

Originally posted by Loriel
I blame Stefan's scary way to calculate the movement that happens if you walk against an edge and thus get pushed to the side.

That's what I first suspected, however, before posting, I put myself on integer coordinates, then pressed up enough to move a little bit. My coordinates were then a float value not divisible by 0.0625, so that just goes to show that Graal's internal movement system must also not increment/decrement your coordinates by a 0.0625 divisible amount.

adam · #6 09-29-2003, 04:48 PM

Bandwidth?

Loriel · #7 09-29-2003, 05:06 PM

Quote:

Originally posted by -Ramirez-

That's what I first suspected, however, before posting, I put myself on integer coordinates, then pressed up enough to move a little bit. My coordinates were then a float value not divisible by 0.0625, so that just goes to show that Graal's internal movement system must also not increment/decrement your coordinates by a 0.0625 divisible amount.

Mhm, do you have lizard shield? I am pretty sure that the default speed is 0.5 tiles/frame, but I dun know how the lizard shielded speed is calculated. :|
Also, on GK, the whole thing gets more messy with mudlib speeds and the like

GoZelda · #8 09-29-2003, 05:18 PM

It seemed to me that a lot of variables seemed to be saved as "integers" or whatever

If you have a calculation, you can never go less then about 5 numbers behind the comma. 33,333...% for example, is, i believe,
33,33333%
What also questions me... is there a way to change values to integer values? It's possible for sure - when i calculated some stuff of the Magic points on GK, i noticed it was 4.2 instead of 4.2, so i guess it must be able to change values to integer values...

I think that Graal saves all x's and y's as integers or floats (?????) ... Wait, that doesn't makes sense, if you press F5, you see numbers like 38.8575040382... I guess that if Graal sends data to the player it becomes integers immediatly or something.

DustyPorViva · #9 09-29-2003, 05:26 PM

I'm going to take a wild guess and say when you move diagonally you move at speed squareroot 2...

For it not being divisible of .0625, it might not me, but it goes to the nearest pixel.

Go ahead Kai, say I'm wrong

GoZelda · #10 09-29-2003, 05:41 PM

Quote:

Originally posted by DustyPorViva
Go ahead Kai, say I'm wrong

Can i say it Kai? Can i say it? Pleaaaase? lol

-Ramirez- · #11 09-29-2003, 05:48 PM

Quote:

Originally posted by Loriel
Mhm, do you have lizard shield?

Yes.

Quote:

Originally posted by Loriel
I am pretty sure that the default speed is 0.5 tiles/frame, but I dun know how the lizard shielded speed is calculated. :|

0.5 is also what I've always determined it to be. I also always thought the Lizard shield was 0.6, but with the weird coordinates you end up on, that can't be right.

Quote:

Originally posted by GoZelda
What also questions me... is there a way to change values to integer values?

Of course, int().

Quote:

Originally posted by GoZelda
I think that Graal saves all x's and y's as integers or floats (?????) ... Wait, that doesn't makes sense, if you press F5, you see numbers like 38.8575040382... I guess that if Graal sends data to the player it becomes integers immediatly or something.

If it's not an integer or a float value, what could it possibly be? Of course it's going to be one of the two. No, the data isn't an integer, it's a decimal with 1 digit following the period, or at least that's what I've seen when testing this.

Quote:

Originally posted by DustyPorViva
I'm going to take a wild guess and say when you move diagonally you move at speed squareroot 2...

Even though this doesn't have a whole lot to do with what I posted, your diagonal speed is slightly higher than your normal speed. Without the Lizard shield, it's 0.7071068 (sqrt(0.5)), and around 0.8485583 (which I don't know of any calculation that equals this amount, or even relatively close) with it.

Quote:

Originally posted by GoZelda

Can i say it Kai? Can i say it? Pleaaaase? lol

Too late.

GoZelda · #12 09-29-2003, 06:01 PM

Quote:

Originally posted by -Ramirez-
Even though this doesn't have a whole lot to do with what I posted, your diagonal speed is slightly higher than your normal speed. Without the Lizard shield, it's 0.7071068 (sqrt(0.5)), and around 0.8485583 (which I don't know of any calculation that equals this amount, or even relatively close) with it.

Mh, maybe this is because two keys are pressed?

DustyPorViva · #13 09-29-2003, 06:18 PM

If you press two keys you move diagonally, which is a slightly longer distance then horizontally or vertically, which could alter the coordinates from being naturally divisible by the speed you move.

-Ramirez- · #14 09-29-2003, 06:23 PM

Quote:

Originally posted by DustyPorViva
If you press two keys you move diagonally, which is a slightly longer distance then horizontally or vertically, which could alter the coordinates from being naturally divisible by the speed you move.

Oh... of course, sorry, I guess I was too set on thinking something else. However, what I mentioned about coordinate inaccuracy says that I only moved up, not diagonal, and my coordinates were still messed up.

Ningnong · #15 09-29-2003, 08:45 PM

Do you always walk the same speed, regardless of frames per second?

If so, then Graal uses a frame-rate independent movement system.

Meaning, the more frames/second you have the slower the co ordinates increment while you walk. Game engines record the time since the last frame.

eg, Y = Y + ( (0.6/1000) * timeElapsed )
1000 milliseconds in 1 second, so you divide 0.6 by 1000 .

y = increasing.

- I talk to Boco alot