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From: frisk@rhi.hi.is (Fridrik Skulason)
Newsgroups: comp.sys.ibm.pc.programmer
Subject: Drawing circles with MSC 5.00
Message-ID: <1738@krafla.rhi.hi.is>
Date: 29 May 90 11:07:36 GMT
Reply-To: frisk@rhi.hi.is (Fridrik Skulason)
Organization: University of Iceland (RHI)
Lines: 53


I have noticed a minor problem when drawing circles in MSC 5.00, namely that
the circle sometimes seems be one pixel too large.

Take the following program for example: 

	#include <stdio.h>
	#include <graph.h>

	main()
	{
	    _setvideomode(_ERESCOLOR);
	    _moveto(50,90);_lineto(80,90); 
	    _ellipse(_GBORDER,61,90,69,95);  /* upper limit of circle = 90 */
	    getch();
	    _setvideomode(_TEXTC80);
	}

It is supposed to produce something like this:

line 90         *******************************
                            **   **                    
                           *       *       
                           *       *       
                            **   **   
                              ***

Instead I get something like this:

                              ***
line 90         *******************************
                           *       *       
                           *       *       
                            **   **   
                              ***

where the top of the circle seems to be one pixel too high. This effect
only happens in certain cases, which seems to indicate a minor bug in the
library.  My questions:

I only have MSC 5.00 - does this effect also appear in the latest versions ?

I could solve this by using Turbo C, (which should have been used
to start with), but then I would have to rewrite a considerable part of the
application.  Does anyone know of another C compiler with MSC-like
graphics functions, without this problem ?

-frisk

-- 
Fridrik Skulason      University of Iceland  |       
Technical Editor of the Virus Bulletin (UK)  |  Reserved for future expansion
E-Mail: frisk@rhi.hi.is    Fax: 354-1-28801  |