The Exact Center

[Chompy]

Originally Posted by Stefan

The blocking part of "showcharacters" and players is x=0.5, y=1, width=2, height=2, so the center would be x=1.5 and y=2

:O

[Crow]

If I want the exact center, and seriously, the exact one, I just do the following:

PHP Code:

temp.cx = player.x + 1.5 - 1 / 32;
temp.cy = player.y + 2 - 1 / 32; 


Well, thats the center of the part normally blocking, the 32*32 pixels at the bottom of the body Dusty pointed out. Why 1 / 32? Thats half a pixel ;P Very nice to remember I guess :]

[Chompy]

Originally Posted by Crow

If I want the exact center, and seriously, the exact one, I just do the following:

PHP Code:

temp.cx = player.x + 1.5 - 1 / 32;
temp.cy = player.y + 2 - 1 / 32; 


Well, thats the center of the part normally blocking, the 32*32 pixels at the bottom of the body Dusty pointed out. Why 1 / 32? Thats half a pixel ;P Very nice to remember I guess :]

or

PHP Code:

temp.cx = player.x + 23.5/16;
temp.cy = player.y + 31.5/16; 


which is Loriels' method that he used in his Movement system ;o

But his movement system is compatible with gs1 so I've rewritten his movement system to work with gs2, and to use less cpu (gs1 didn't support temp. variables ) and I added running to it ;o

[Inverness]

Originally Posted by Chompy

PHP Code:

temp.cx = player.x + 1.46875;
temp.cy = player.y + 1.96875; 


uhm?

Thats just going from tiles to pixels.

[Chompy]

Originally Posted by Inverness

Thats just going from tiles to pixels.

PHP Code:

temp.cx = player.x + 23.5/16;
temp.cy = player.y + 31.5/16; 


then

[Polo]

You should not be subtracting 1/32 (half a pixel), as doing so will give you an innacurate result.

If you're wondering why, it's because a pixel has shape to it: it has both a left and right edge. The easiest way to demonstrate this is to draw 2 adjoining squares on a piece of paper with 0 and 2 written on the outside bottom corners, and 1 written on the touching corner. I'm fairly sure that you'll agree the centre is at 1 and not 0.5.

PHP Code:

  ___ ___
 |   |   |
 |___|___|
 0   1   2 


In light of that, the usual coordinates to use for movement are a 2 by 2 square centred exactly on 1.5, 2 (just as Stefan said).

[Kyranki]

So what's the best calculation then Storm?

PHP Code:

temp.cx = player.x + 1;
temp.cy = player.y + 1; 


When using that the center is too 'high'. I seem to have started something here... o_o

[Polo]

Originally Posted by Kyranki

So what's the best calculation then Storm?

For movement systems, I have always used...

NPC Code:

---

temp.cx = player.x + 1.5;

temp.cy = player.y + 2;

---

Which give the center of the players base (thats the area which blocks against walls). Add/subtract 1 from those positions to find the respective edges of this region.

[Kyranki]

Originally Posted by Polo

For movement systems, I have always used...

NPC Code:

---

temp.cx = player.x + 1.5;

temp.cy = player.y + 2;

---

Which give the center of the players base (thats the area which blocks against walls). Add/subtract 1 from those positions to find the respective edges of this region.

I'm just getting the center of the player to calculate hit detection using the center of the attacker and each possible person to hit.

[Googi]

Originally Posted by Kyranki

I'm just getting the center of the player to calculate hit detection using the center of the attacker and each possible person to hit.

So what are you looking for? The center of the player's "image"? player.x + 1 and player.y + 1.5 should do it for you.

[Inverness]

Originally Posted by Googi

So what are you looking for? The center of the player's "image"? player.x + 1 and player.y + 1.5 should do it for you.

Not quite. Player images are 3x3 tiles.

Originally Posted by Stefan

The blocking part of "showcharacters" and players is x=0.5, y=1, width=2, height=2, so the center would be x=1.5 and y=2

Do what Stefan said.

[Googi]

Originally Posted by Inverness

Not quite. Player images are 3x3 tiles.

That might be the programmed size, but the image the player sees is not three tiles across.

[xXziroXx]

Originally Posted by Googi

That might be the programmed size, but the image the player sees is not three tiles across.

Since he's trying to check if the player is it, and not anything with the image, he should do what Stefan said which gives you the progammed size (the only area where triggers are checked).

[zokemon]

Originally Posted by Chompy

PHP Code:

temp.cx = player.x + 1.46875;
temp.cy = player.y + 1.96875; 


uhm?

This is true but often you are off-setting it the the pixel down right of your "center" so most just settle with 1.5,2. Unless you are doing like a movement system or something that is checking onwall checks or so, 1.5,2 will work much better for you.

[Inverness]

Originally Posted by Googi

That might be the programmed size, but the image the player sees is not three tiles across.

The image the player sees is centered in the 3x3 box, meaning player.x+1.5 would be the vertical center of that box and the center of the player image. Stefan said center of player image would be player.x+1.5 and player.y+2