Misc/abrash-black-book
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Remove colour attributes from body and strip most of the font tags out

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James Gregory 2013-12-30 13:57:02 +11:00
commit c1f88ddb41
362 changed files with 1632 additions and 1706 deletions
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45-03.html
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@ -24,7 +24,7 @@
<!--CHAPTER=45//-->
<!--PAGES=846-851//-->
<!--UNASSIGNED1//-->
<!--UNASSIGNED2//--></HEAD><BODY LINK=#0000FF ALINK=#000099 VLINK=#0000FF BGCOLOR=#FFFFFF>
<!--UNASSIGNED2//--></HEAD><body>
<CENTER>
<TABLE BORDER>
@ -38,7 +38,7 @@
<P><BR></P>
<P>Also, page flipping wastes a good deal of time waiting for the page to flip at the end of the frame. Dirty-rectangle animation never needs to wait for anything because partially drawn images are never present in display memory. Actually, in one sense, partially drawn images are sometimes present because it&rsquo;s possible for a rectangle to be partially drawn when the scanning raster beam reaches that part of the screen. This causes the rectangle to appear partially drawn for one frame, producing a phenomenon I call &ldquo;shearing.&rdquo; Fortunately, shearing tends not to be particularly distracting, especially for fairly small images, but it can be a problem when copying large areas. This is one area in which dirty-rectangle animation falls short of page flipping, because page flipping has perfect display quality, never showing anything other than a completely finished frame. Similarly, dirty-rectangle copying may take two or more frame times to finish, so even if shearing doesn&rsquo;t happen, it&rsquo;s still possible to have the images in the various dirty rectangles show up non-simultaneously. In my experience, this latter phenomenon is not a serious problem, but do be aware of it.
</P>
<H3><A NAME="Heading7"></A><FONT COLOR="#000077">Dirty Rectangles in Action</FONT></H3>
<H3><A NAME="Heading7"></A>Dirty Rectangles in Action</H3>
<P>Listing 45.1 demonstrates dirty-rectangle animation. This is a very simple implementation, in several respects. For one thing, it&rsquo;s written entirely in C, and animation fairly cries out for assembly language. For another thing, it uses far pointers, which C often handles with less than optimal efficiency, especially because I haven&rsquo;t used library functions to copy and fill memory. (I did this so the code would work in any memory model.) Also, Listing 45.1 doesn&rsquo;t attempt to coalesce rectangles so as to perform a minimum number of display-memory accesses; instead, it copies each dirty rectangle to the screen, even if it overlaps with another rectangle, so some pixels are copied multiple times. Listing 45.1 runs pretty well, considering all of its failings; on my 486/33, 10 11x11 images animate at a very respectable clip.
</P>
<P><B>LISTING 45.1 L45-1.C</B></P>
@ -317,7 +317,7 @@ void EraseEntities()
<hr width="90%" size="1" noshade>
<div align="center">
<font face="Verdana,sans-serif" size="1">Graphics Programming Black Book &copy; 2001 Michael Abrash</font>
Graphics Programming Black Book &copy; 2001 Michael Abrash
</div>
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<!-- reference_subfoot = footer -->