sprite roatation

Comments

• iby

  November 2001

  : 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:
  
  [code]
  
  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;
  
  [/code]
  
  Iby
  
  
• iby

  November 2001

  [code]
  
  Eh... typo... ;-)
  
  :
  : { let's assume [b]Spr2[/b] is the sprite w want to rotate.
  : the rotated image will be stored into Spr1 }
  :
  [/code]
  
  
  Iby
  
  
  
  
• beardtrix

  November 2001

  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?
  
  
• iby

  November 2001

  : 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
  
  
• beardtrix

  November 2001

  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?
  
  
• iby

  November 2001

  : 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?
  :
  :
  
  
  [code]
  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.
  [/code]
  
  
  Use Watch to check the content of FLOR and FLOK variables
  after rotation...
  
  
  Iby
  
  
• beardtrix

  November 2001

  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?
  
• iby

  November 2001

  : 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
  
• Jeff P.

  December 2001

  Hello!
  I was just surfing around at sourceforge and ran across something that might help...
  
  http://sourceforge.net/projects/burn/