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sprite roatation

Fri, 23 Nov 2001 07:54:08 -0700

i've made a tile based level with a top down view. I have a sprite of a tank which can move up, down, left and right. the only thing i can't figure out is how to rotate the tank easily. I'm also looking for some sprite flipping/rotating routines if anyone has some.

Re: sprite roatation

Sun, 25 Nov 2001 20:42:07 -0700

: i've made a tile based level with a top down view. I have a sprite of a tank which can move up, down, left and right. the only thing i can't figure out is how to rotate the tank easily. I'm also looking for some sprite flipping/rotating routines if anyone has some.
:
:
:

All you need is to rotate by 90 degree? That's simple.
But let's first clarify few things:
Don't try to rotate sprite while game is in progress.
Make sure that you create 4 versions of the sprite
while loading or initializing game. Everything else
is not efficient and will slow your game down.

Now let's go back to sprite rotation:
The sprites are normally stored in arrays of bytes.
If H and W are height and width of the sprite,
the array size is H*W. So all you have to do is
read one sprite horizontally and write to another
vertically. If the H and W are not the same, make sure
your target sprite can hold the data.
If H and W are the same, thins are even simpler:


var spr1,spr2,... :array[1..H*H] of byte;  { H and W are same }
    i,j,k,l:byte;

;
;
;

{ let's assume Spr1 is the sprite w want to rotate.
  the rotated image will be stored into Spr2 }

  for i:=1 to H do
    for j:=1 to H do
      begin
        k:=i+j*H;
        l:=j+i*H;
        spr1[k]:=spr2[l];
      end;

Iby

Re: sprite roatation

Sun, 25 Nov 2001 20:44:00 -0700


Eh... typo... 

: 
: { let's assume Spr2 is the sprite w want to rotate.
:   the rotated image will be stored into Spr1 }
:

Iby

Re: sprite roatation

Mon, 26 Nov 2001 07:01:52 -0700

ok, how do i use this to put the rotated tile on the screen (i'm using puttile(x,y,name,where) ) would i just use the new array with the rotated tile in it as name?

Re: sprite roatation

Mon, 26 Nov 2001 18:40:44 -0700

: ok, how do i use this to put the rotated tile on the screen (i'm using puttile(x,y,name,where) ) would i just use the new array with the rotated tile in it as name?
:
:

You got it...

Iby

Re: sprite roatation

Tue, 27 Nov 2001 08:04:21 -0700

ok, i understand the code but i'm having some trouble. In the example you used

var spr1,spr2 : array etc etc

the thing is, i'm using something similar to this to handle my sprites:

type spr1 = array [1..20*20] of byte

and then doing this to draw the sprite:

const floor : spr1 = (
0,0,0,0,1,0,2,0,2,0,0,
0,1,0,2,0,2,0,2,0,1,0, etc etc

when i try and implement the code you suggested with this array, it wont let me. how do i get around this?

Re: sprite roatation

Tue, 27 Nov 2001 10:33:49 -0700

: ok, i understand the code but i'm having some trouble. In the example you used
:
: var spr1,spr2 : array etc etc
:
: the thing is, i'm using something similar to this to handle my sprites:
:
: type spr1 = array [1..20*20] of byte
:
: and then doing this to draw the sprite:
:
: const floor : spr1 = (
: 0,0,0,0,1,0,2,0,2,0,0,
: 0,1,0,2,0,2,0,2,0,1,0, etc etc
:
: when i try and implement the code you suggested with this array, it wont let me. how do i get around this?
:
:

type spr=array[1..9] of byte;

const flor:spr=(1,2,3,
                4,5,6,
                7,8,9);

var i,j,k,l:byte;
    flok:spr;

begin
  for i:=1 to 3 do
    for j:=1 to 3 do
      begin
        k:=(i-1)*3+j;
        l:=i+(j-1)*3;
        flok[k]:=flor[l];
      end;
end.

Use Watch to check the content of FLOR and FLOK variables
after rotation...

Iby

Re: sprite roatation

Wed, 28 Nov 2001 06:02:11 -0700

ok, it's working - sort of - it puts some sort of image on the screen! it takes the original image and messes it up a bit :(

I understand the theory, i need to read my sprite array from left colom to right colom instead of top row to bottom row. i just can't implement it!!! could you take a look at my code for me and have a mess around please?

Re: sprite roatation

Wed, 28 Nov 2001 10:33:37 -0700

: ok, it's working - sort of - it puts some sort of image on the screen! it takes the original image and messes it up a bit :(
:
: I understand the theory, i need to read my sprite array from left colom to right colom instead of top row to bottom row. i just can't implement it!!! could you take a look at my code for me and have a mess around please?
:

Hmmm.... If I understand it correctly you are
trying to modify your "put_sprite" routine...
That's of course possible but not recommended.
It's better to keep it as it is (keep it general)
and just rotate image. Send me the full source
and I will take a good look at it. I have somewhere
code for my sprite editor with sample sprites.
It is old and if I had to redo it, I would probably
change few things. But it works quite nice and
I am sort of lazy . If you want I could
email it to you.

Iby

Re: sprite roatation

Thu, 06 Dec 2001 01:43:58 -0700

Hello!
I was just surfing around at sourceforge and ran across something that might help...

http://sourceforge.net/projects/burn/