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From: ForthNet@willett.UUCP (ForthNet articles from GEnie)
Newsgroups: comp.lang.forth
Subject: Graphics
Message-ID: <291.UUL1.3#5129@willett.UUCP>
Date: 19 Jan 90 23:18:42 GMT
Organization: Latest Link in ForthNet Chain (Pittsburgh, PA)
Lines: 90


 Date: 01-17-90 (23:46)              Number: 1715 (Echo)
   To: MARK SMILEY                   Refer#: 1709
 From: MIKE SPERL                      Read: NO
 Subj: SCRNSAV.SEQ                   Status: PUBLIC MESSAGE

 Mark,

 >how about a faster version of CLIP_FILL_ELLIPSE ?

     Here's the first step: smart ellipse with automatic clipping.  
 What about drawing segments of ellipses on the display?  Would 
 this be useful?  All the tools are already available (with minor 
 mods). 

 : CLIP4PIXELS  ( -- )    \ uses values of:  x y xc yc
     inline                             \ XC @ X +  YC @ Y +
         mov ax, xc   add ax, ' x 3 + #)   push ax
         mov ax, yc   add ax, ' y 3 + #)   1push
     end-inline
     clip-dot
     inline                             \ XC @ X -  YC @ Y +
         mov ax, xc   sub ax, ' x 3 + #)   push ax
         mov ax, yc   add ax, ' y 3 + #)   1push
      end-inline
     clip-dot
     inline                             \ XC @ X +  YC @ Y -
         mov ax, xc   add ax, ' x 3 + #)   push ax
         mov ax, yc   sub ax, ' y 3 + #)   1push
     end-inline
     clip-dot
     inline                             \ XC @ X -  YC @ Y -
          mov ax, xc   sub ax, ' x 3 + #)   push ax
         mov ax, yc   sub ax, ' y 3 + #)   1push
     end-inline
     clip-dot ;

 : ELLIPSE    ( xc yc a0 b0 -- ) \ smart ellipse
     inline              \ clip?
     mov bx, sp
     mov ax, 6 [bx]      \ xc
     cmp ax, 2 [bx]      \ xc - a0 check left edge
      js 1 $              
     mov dx, 4 [bx]      \ yc
     cmp dx, 0 [bx]      \ yc - b0 check top edge
     js 1 $              
     add ax, 2 [bx]      \ xc + a0 check right edge
     cmp ax, hres
     jge 1 $     
      add dx, 0 [bx]      \ yc + b0 check bottom edge
     cmp dx, vres
     jge 1 $     
     xor ax, ax          \ false
      1push           \ false -> don't clip
 1 $: mov ax, # -1
     1push           \ true -> clip
     end-inline          \ clip?
     if   ['] CLIP4PIXELS IS ELLIPSE_PIXELS
     else ['] SET4PIXELS IS ELLIPSE_PIXELS
     then  (ELLIPSE) ;

 commment:
 \ If you use smart ellipse, these words are redundant
 : CLIPELLIPSE    ( xc yc a0 b0 -- )
     ['] CLIP4PIXELS IS ELLIPSE_PIXELS  (ELLIPSE) ;
 : CLIPELLIPSE?    ( xc yc a0 b0 -- )
     clip? \ substitute the inline code from ellipse here
      if   ['] SET4PIXELS IS ELLIPSE_PIXELS
     else ['] CLIP4PIXELS IS ELLIPSE_PIXELS
     then   (ELLIPSE) ;
 comment;

     Another suggestion: add
         ASSEMBLER INLINEON
 to tthe beginning af files containing assembler words (inluding 
 high level words with inline code), and 
         ASSEMBLER INLINEOFF
         ONLY FORTH ( optional )
 at the end.  This makes a big difference in the dot and line words 
 particularly. 

     I've got BARNEX running with the new words, now.  Nice.  If 
 you want to send me something, I'd love a copy of your new book,
 615 E. 68th St., Richfield, MN 55423.  ;-) 

     - Mike -

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