¢*******+++++++++*********+++++++++****¢¢ 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.¢Youcan 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¢thiscommand 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 mode's¢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!!¢¢ #########%%%%%%%%########%%%%%%%%####¢
