Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!utgpu!water!watmath!clyde!rutgers!lll-lcc!ames!ucbcad!ucbvax!INGRES.BERKELEY.EDU!hatcher
From: hatcher@INGRES.BERKELEY.EDU.UUCP
Newsgroups: comp.sys.amiga
Subject: Re: Dropshadow
Message-ID: <8705010752.AA10059@ingres.Berkeley.EDU>
Date: Fri, 1-May-87 03:52:01 EDT
Article-I.D.: ingres.8705010752.AA10059
Posted: Fri May  1 03:52:01 1987
Date-Received: Sat, 2-May-87 03:46:09 EDT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: University of California, Berkeley
Lines: 87
Summary: Here's source to add bitplane to WB

Recently there has been some interest in how Jim Mackraz added a bitplane
to Workbench in his Dropshadow program. He is still keeping the source
to Dropshadow secret last I heard, but he was kind enough to release an
excerpt from it on a local BBS (the part that adds the extra bitplane).

Here it is; keep in mind that this is a code *fragment*, so presumably
you should use it as a springboard rather than try to use it without looking
it over! I added a C-style comment to the very end so you'd know whether
you received it intact or not.
	Enjoy,
		Doug Merritt		ucbvax!ingres!hatcher

P.S. Chuck McManis's recent (4/30) explanation of the method would probably
accompany this quite well; you did save it didn't you?

----------------------- apply andy's drill here ------------------------

Date: 10-APR-87  01:03 AM
Subj: From Jim Mackraz- Code (F)


    wbscreen = window->WScreen;     /* find it  */

    /* new 3-deep bitmap will replace the one in WB's RInfo */
    if (!(ribitmap = (struct BitMap *)
        AllocMem((LONG) sizeof(struct BitMap), (LONG)MEMF_PUBLIC|MEMF_CLEAR)))
    {
        D( printf("alloc bitmap failed\n") );
        goto EXITING;
    }
    InitBitMap(ribitmap, 3L, (LONG) wbscreen->Width, (LONG)wbscreen->Height);

    /* allocate bitmap for my rastport view of single bitplane  */
    if (!(bmap2 = (struct BitMap *)
        AllocMem((LONG) sizeof(struct BitMap), (LONG)MEMF_PUBLIC|MEMF_CLEAR)))
    {
        D( printf("alloc bitmap failed\n") );
        goto EXITING;
    }

    /* my rendering bit map: depth 1    */
    InitBitMap(bmap2, 1L, (LONG) wbscreen->Width, (LONG) wbscreen->Height);

    if (!(bmap2->Planes[0] =
        (UBYTE *) AllocRaster((LONG) wbscreen->Width, (LONG)wbscreen->Height)))
    {
        D( printf("alloc raster failed\n") );
        goto EXITING;
    }

    /* get a rastport, and set it up for rendering into bmap2   */
    if (!(rport2 = (struct RastPort *)
        AllocMem((LONG) sizeof (struct RastPort), (LONG) MEMF_PUBLIC)))
    {
        D( printf("alloc rastport failed\n") );
        goto EXITING;
    }
    InitRastPort(rport2);
    rport2->BitMap = bmap2;

    SetRast(rport2, 0L);

    /* set up new bitmap for RInfo  */
    save_bitmap =  wbscreen->ViewPort.RasInfo->BitMap;
    ribitmap->Planes[0] = save_bitmap->Planes[0];
    ribitmap->Planes[1] = save_bitmap->Planes[1];
    ribitmap->Planes[2] = bmap2->Planes[0];

    Forbid();

    /* add our extra plane to the bit-map as viewed by
     * the WB ViewPort (WB should never know the difference)
     */
    wbscreen->ViewPort.RasInfo->BitMap = ribitmap;

    Permit();

    it_is_done = 1;

    shadowColors(wbscreen);

    /* put viewport changed into effect */
    MakeScreen(wbscreen);
    RethinkDisplay();


/**************************** end of code fragment *********************/