/* boxomatic.c by Gregg Williams finished 29 May 86 BYTE Magazine PO Box 372 Hancock NH 03449 Phone: 603-924-9281 BIX: greggw This program shows: dual playfield with bottom playfield visible "under" top playfield and scrolling in two dimensions use of the following functions: OpenLibrary, InitBitMap, InitView, InitVPort, GetColorMap, AllocRaster, BltClear, MakeVPort, MrgCop, LoadView, WaitTOF, FreeMemory, CloseLibrary, SetRast, SetAPen, RectFill, FreeRaster, FreeVPortCopLists, FreeCprList, FreeColorMap I have kept this program as simple as possible to make the workings of a scrolling dual-playfield as obvious as possible. I am placing this source code in the public domain as a small repayment of the debt I owe the many people who have similarly contributed their work over the years. Please feel free to study this program, modify it, and use it as a "skeleton" for a larger, more powerful program that needs a dual playfield (game designers, take note). This program compiles under Aztec C version 3.20A (using the +L option), the c32.lib library, and Kickstart 1.1; it should compile under Lattice C, but I haven't tried it. I tried to get this program so it would compile under both 16-bit-int Aztec C and Lattice C but was unable to get rid of two ptr/int warnings for both OpenLibrary and AllocRaster. If you know how to do this, please let me know. --Gregg Williams */ /* 1-15-87 - Added the include of and added some L's after some constants being passed to Amiga functions. Now works with 16 bit ints. jg */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* An overview of Amiga graphics--what's where: View (what you see on the screen, contains important Modes variables | for things like interlaced screen, dual playfield, and others) | |--(points to) V ViewPort1 --> ViewPort2 --> ... --> ViewPortN | (A ViewPort is a horizontal slice of the screen; here you specify | height, width, depth (determines # of colors available), | sprites, type of display: dual-playfield, resolution, interlace, | hold-and-modify, extra-halfbright) | (The variables DxOffset and DyOffset position the upper left | corner of the viewport on the screen) | (If there are multiple viewports, the first one points to the | second, the second to the third, etc.) |\ | \ | V | ColorMap (establishes the colors available to this viewport) V RasInfo (contains RxOffset, RyOffset, which mark the pixel within | the bitmap (see below) that will be positioned in the | upper left corner of the viewport--you can scroll the | bitmap in a viewport by changing these values) | | RastPort (contains info on pen colors, text info, pointers | / to GelsInfo, AreaInfo (when needed) | / | / V V BitMap (contains actual memory that represents an area of image; the image can be larger than what is visible on the screen) */ #define DEPTH 3L /* depth of playfield 1, (scrolling, on bottom) */ #define WIDTH 640L /* dimensions of playfield 1 */ #define HEIGHT 400L /* Since pf1 is behind pf2, it can be any size you want it--you could make it a long, thin horizontal strip if you wanted to. Just be sure that nothing unexpected shows through the "hole" in the top pf.... */ #define DEPTH2 2L /* depth of playfield 2 (stationary, on top) */ #define WIDTH2 320L /* dimensions of playfield 2 */ #define HEIGHT2 200L #define VPWIDTH 320L /* dimensions of the viewport */ #define VPHEIGHT 200L /* In this simple case, the view (i.e., what you see on the screen) is made entirely from one viewport. If the 320 number looks odd to you, you're not alone. I originally had WIDTH2 and VPWIDTH to be 320, but a thin strip of pf1 showed through the right margin of the screen. If you can explain why you need the 320 value, please let me know.... */ #define NOT_ENOUGH_MEMORY -1000 #define PF1_BACKGD 7L #define PF2_BACKGD 1L #define PF2_FRAME 2L /* construct a simple display */ struct View view; struct ViewPort viewport; /* pointer to colormap structure, dynamically allocated */ struct ColorMap *cm; struct RasInfo rasinfo, rasinfo2; struct BitMap bitmap, bitmap2; struct RastPort rastport, rastport2; extern struct ColorMap *GetColorMap(); struct GfxBase *GfxBase; /* save the pointer to the old view so we can restore it later */ struct View *oldview; USHORT colortable[]={ /* colors 0-7, for playfield 1 clear, gold, cyan, cherry, brown, green, gray, blue */ 0x000, 0xfb0, 0xccc, 0xf15, 0xa50, 0x0c5, 0x777, 0x77f, /* colors 8-11, for playfield 2 clear, blue, black, rose */ 0x000, 0x55f, 0x000, 0xc57, 0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0 }; /* Remember that, even though you paint into playfield 2 with brush numbers 0-7 (actually, 0-3 in this 2-bit playfield), the computer maps them to colors 8-15.... */ UWORD *colorpalette; /* * * * * * * * * * * * * * * * * * * * * * * * * */ main(argc, argv) int argc; char *argv[]; { LONG i, n; SHORT nmax; SHORT pf1_xmove, pf1_ymove; UBYTE *displaymem; static LONG pf2colr[] = {1, 2, 3, 1}; /* 'nmax' determines how long the display runs; see below */ if ( argc == 2 ) nmax = atoi(argv[1]); /* get value of 'nmax' from user input */ else { nmax = 10; /* default value */ } /* Open the graphics library.... */ GfxBase = (struct GfxBase *)OpenLibrary("graphics.library",0L); if (GfxBase == NULL) exit(100); /* Save the current view to restore it later. */ oldview = GfxBase->ActiView; InitView(&view); /* initialize view */ InitVPort(&viewport); /* init viewport */ view.ViewPort = &viewport; /* link view into viewport */ view.Modes = DUALPF + PFBA; /* sets dual playfield w/ pf2 on top */ viewport.Modes = DUALPF + PFBA; /* sets dual playfield w/ pf2 on top */ /* Init bit map (for rasinfo and rastport). */ InitBitMap(&bitmap, DEPTH, WIDTH, HEIGHT); InitBitMap(&bitmap2, DEPTH2, WIDTH2, HEIGHT2); /* Establish rast.ports for playfield 1, then playfield 2. */ InitRastPort(&rastport); rastport.BitMap = &bitmap; InitRastPort(&rastport2); rastport2.BitMap = &bitmap2; /* Init RasInfos for playfield 1, then playfield 2. */ rasinfo.BitMap = &bitmap; rasinfo.RxOffset = 0; rasinfo.RyOffset = 0; rasinfo.Next = &rasinfo2; /* link this RasInfo to the next one */ rasinfo2.BitMap = &bitmap2; rasinfo2.RxOffset = 0; rasinfo2.RyOffset = 0; rasinfo2.Next = NULL; /* Now specify critical characteristics.... */ viewport.DWidth = VPWIDTH; viewport.DHeight = VPHEIGHT; viewport.RasInfo = &rasinfo; /* Initialize the color map, which has 32 entries (sprites take up the top 16). */ cm = GetColorMap(32L); /* If no memory for color map, reclaim memory and exit. */ if (cm == NULL) { FreeMemory(); exit(100); } /* 'colorpalette' points to the color table for this color map. */ colorpalette = (UWORD *)cm->ColorTable; /* We initialize this color table with the values from our array. */ for(i=0; i<32; i++) { *colorpalette++ = colortable[i]; } /* Copy the color table into the viewport structure. */ viewport.ColorMap = cm; /* Allocate space for bitmap 1, then bitmap 2. */ for(i=0; i= 638L-320L) { pf1_xmove = -pf1_xmove; n = n + 1; /* sorry, no C jargon here--code should be readable */ } if (rasinfo.RyOffset <= 2L || rasinfo.RyOffset >= 398L-200L) { pf1_ymove = -pf1_ymove; n = n + 1; } /* Reexecute this trio of instructions to make the changes visible. */ MakeVPort(&view, &viewport); MrgCop(&view); LoadView(&view); /* Slow it down to one move per video frame: this routine waits until the electron gun in the video display is about to start drawing a new frame. */ WaitTOF(); } /* end of 'for' loop */ /* Restore the system to its original state. */ LoadView(oldview); /* The two statements that follow return the memory allocated by this program to the system for general use. If you do not do this, you lose access to a big chunk of memory each time you run this program and, eventually, the Amiga refuses to work properly for lack of available memory. */ FreeMemory(); CloseLibrary(GfxBase); } /* end of main() */ /* * * * * * * * * * * * * * * * * * * * * * * * * * * */ draw_playfields() /* This routine draws playfields 1 and 2 for later display. */ { LONG x, y, temp, color1, color2; /* Draw "window" of playfield 2 (the stationary one on top). */ SetRast( &rastport2, PF2_BACKGD ); /* flood raster with backgd color */ SetAPen( &rastport2, PF2_FRAME ); /* this is the color of the "frame" */ RectFill( &rastport2, 0L, 45L, 320L, 155L ); SetAPen( &rastport2, 0L); /* this is the "transparent" window (color 0) that allows us to see through to the lower playfield (pf1) */ RectFill( &rastport2, 10L, 50L, 310L, 150L ); /* - - - - - - - - - - - - - - - - - - - - */ SetRast( &rastport, PF1_BACKGD ); temp = 1L; for( x=0L; x<=620L-150L; x=x+150L ) { for ( y=20L; y<=380L; y=y+20L) { color1 = temp; /* this code simply generates ever-changing colors for the text */ temp = temp + 1L; if (temp > 7L) temp = 1L; color2 = temp; temp = temp + 1L; if (temp > 7L) temp = 1L; SetAPen(&rastport,color1); SetBPen(&rastport,color2); Move(&rastport,x,y); Text(&rastport,"BAMIGA SECTOR ONE",17L); } } /* end outer 'for' loop */ } /* end draw_playfields */ /* * * * * * * * * * * * * * * * * * * * * * * * * * * */ /* * * * * * * * * * * * * * * * * * * * * * * * * * * */ FreeMemory() /* Return user and system-allocated memory to the system. */ { LONG i; /* Free both bitmaps. */ for (i=0; i