¢*******+++++++++*********+++++++++*¢¢ DOING P/M GRAPHICS IN BASIC XE¢ By Bruce Pleat¢ SySop¢ Mister Message BBS¢ (516) 454-7698¢¢(former member of the OL' HACKERS¢ATARI USER GROUP, Inc.)¢¢¢To turn on PMG in BASIC XE, you first set a GRAPHICS mode, then do a PMGRAPHICS for the "mode" you want.¢You can have three modes:¢¢ 0 Turn PMG OFF¢ 1 "Single-Line" Resolution¢ 2 "Dougle-Line" Resolution¢¢"1" means you use 2 times as much RAM(2048 bytes) and have two times as much detail. "2" means 1024 bytes are used and each line is the height of a GR.7 line, instead of PMG mode 1's GR.8 height. To set the player/missile COLORs, you use the PMCOLOR #,color,hue command.¢¢The PMWIDTH command allows you to define the WIDTH of players...you have SINGLE-width( 1 player is eight GR.7 pixels), DOUBLE-width (1=16 in GR.7) and QUADRUPLE(1 player=32 GR.7 pixels). The wider the player, the lower the resolution, and yet of course the larger it is in WIDTH.¢¢PMCLR # clears the player/missile space of playernumber #. Doing 4-7 for # which usually selects the missile compliment for players 0-3 in this command clears them all.¢¢HITCLR checks for collisions. It has no parameters and you can use it right before you wish to check for collisions via the BUMP command:¢¢ BUMP(panum,aexp) is used as such:¢¢ IF BUMP(4,1) THEN GOTO...¢¢Bump Parameters:¢Players 0-3: 0-3¢Missiles 0-3: 4-7¢Playfield 0-3: 8-11¢¢Now, the only VALID bumps are:¢¢Player to player: BUMP(0-3,0-3) (If first parm=second, 0 is always returned; a player can't hit itself!)¢¢Missile to Player: BUMP(4-7,0-3)¢Player to Colors: BUMP(0-3,8-11)¢Missile to Colors: BUMP(4-7,8-11)¢¢Now to define or move a MISSILE you use:¢¢MISSILE #,X,Y (where X,Y do not correspond to GR.7 or whatever modes X,Y).¢¢To move a PLAYER:¢¢PMMOVE panum [,absleft] [absvert]¢¢Panum is player #0-3, absleft is the player's left bit's LEFT POSITION [Y].¢It can range from 0-255 but the lowest and highest are off the edges.¢¢Absvert is the vertical DISPLACEMENT from its LAST position. (For example, X=X+1, SET 7,1 - lets players that might go off the top/bottom wrap-around to the other side. SET 7,0 [default] just loses them.¢¢PMADR(#) gives the ADDRESS of a player's top. That's where you POKE,BGET, MOVE, or otherwise store the player's data.¢¢Draw your object. Then, redraw it on graph paper in no more than eight boxes wide and 30 high(more is too big). Then, put the following numbers on top of each column from LEFT to right:¢¢ 1 2 4 8 16 32 64 128¢¢Now, add up the "on" or colored-in column values and place them to the side of the line they're added up for.¢¢When you've done that, place those values into a DATA line. Now, do the GRAPHICS mode you want, and any drawings you want to do and any colors you wish to set.¢¢Set the Player/Missile Colors via direct POKEs or PMCOLOR commands. Set your PMGRAPHICS mode and then your PMWIDTH. "1" is best for starters.¢You set it for EACH player/missile you want to use. Do a PMCLR for players 0-3 and then one for missiles, #4 to make it simple. Do a RESTORE to your DATA line for your PLAYER 0. Now do the following:¢¢ FOR A=1 TO (# of lines in Player)¢ READ B:POKE PMADR(0)+A,B¢ NEXT A¢¢Repeat the RESTORE through NEXT A sequence for each player ONLY. Set the missiles with this routine:¢¢ FOR A=1 TO ....¢ READ B:POKE PMADR(0)+A,PEEK(PMADR(0)+A)!(2^player+):NEXT A¢¢PMMOVE each player where you want it.¢MISSILE each missile where you want it. And, HITCLR the screen.¢¢Jump out of your set-up routine [PROCEDURE??) and into the main one which can do the following:¢¢PMMOVE a player¢MISSILE a missile (getting tired of that...)¢HITCLR:BUMP ....(always a HITCLR right after a BUMP) to check for collision¢¢Oh, the Missile and Player vertical movement (OFFSETs) are perfect for the VSTICK command!!¢¢ #########%%%%%%%%########%%%%%%%%##¢¢¢This article is from the 'Ol hackers newsletter, and was submitted by Jim Cutler. It was tidied by Dean Garraghty. I'm sorry if there are mistakes in here, but the files came in a weird format, which took some editing.¢
