Principals of SPRITES
                       
by John Blackmer, for MCUC Magazine

  Since some of the stronger points of the Commodore family of computers are the excellent graphics capabilities, it ' s only logical that animation would become an extention of those points .  Let ' s face it, the games we all play depend on it . 

In general, the way one would animate something, say a spinning ball, would be by drawing one position then changing the position  ( or angle of view )  and redrawing the ball over the 1st one .  Continuous and rapid changes create the illusion of movement .  In BASIC, you can accomplish this in a couple of ways .  Both are limited and, as we all know, basic is slow .  

The first, and probably the easiest, is employing the use of sprites .  Sprites, aka MOBs  ( Moveable Object Blocks ),  are small programmable areas of the computer ' s memory dedicated especially for this function .  The 64 / 128 have 8 sprites available .  Numbered from 1 to 8 in order of depth into the screen .  That is, when employed, sprite  # 1 is in front of  # 2 etc on up to 8 .  

There are many small programs available to help you to design edit and display sprites on the 64 .  I have asked Jim and Bob to put some of these on the disk of the month this month .  Be sure to check out Sprite Designer 64  !  On the 128 it ' s a lot easier .  The designers put a sprite editor right in the ROMs  !  In 40 column mode, type SPRDEF and up pops a screen for designing your sprites .  Here are some additional commands that are built into the 128 / 40 for manipulating your sprites . 

 SPRITE
    Toggles individual sprites on or off and sets assorted characteristics . 

MOVSPR
   Allows you to make your sprite move in any direction at any speed .  

SPRSAV
   Transfers sprite data to a string variable, from a string variable to a sprite, or from sprite to sprite .  

SPRCOLOR
   Sets one of 2 multi color modes for one or all sprites . 

COLLISION
  Handles detection of collision between sprites, display data  ( background ),  and assists in use of a light pen . 

Your programmer ' s manual can explain all of these and the ones not mentioned here . 

The other way of animating your screen is to POKE data onto the screen .  Memory locations 1024 to 2023 on the 64 and the 40 column 128 .  If you poke the screen position with the ascii code  #  of the character you want to display it will show up at that position .  Here ' s a very short progran to illustrate : 

   10 for lo =  1024 to 2023
   20 poke lo,65
   25 pokelo - 1,32
   30 next lo

If you run this program it will show an A running across the screen, left to right untill it reaches the lower right part of the screen .