143 lines
5 KiB
HTML
143 lines
5 KiB
HTML
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<head>
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<meta name="vsisbn" content="1576101746" />
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<meta name="vstitle" content="Michael Abrash's Graphics Programming Black Book, Special Edition" />
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<meta name="vsauthor" content="Michael Abrash" />
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<meta name="vspublisher" content="The Coriolis Group" />
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<meta name="vspubdate" content="07/01/97" />
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<meta name="vscategory" content="Web and Software Development: Game Development,Web and Software Development: Graphics and Multimedia Development" />
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<title>Michael Abrash's Graphics Programming Black Book Special Edition: The Good, the Bad, and the Run-Sliced</title><!-- HEADER -->
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<!--ISBN=1576101746//-->
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<!--TITLE=Michael Abrash's Graphics Programming Black Book Special Edition//-->
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<!--AUTHOR=Michael Abrash//-->
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<!--PUBLISHER=The Coriolis Group, Inc.//-->
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<!--CHAPTER=36//-->
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<!--PAGES=692-693//-->
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</head>
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<body>
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<center>
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<table border="1">
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<tr>
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<td><a href="36-03.html">Previous</a></td>
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<td><a href="index.html">Table of Contents</a></td>
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<td><a href="37-01.html">Next</a></td>
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</tr>
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</center>
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<p><br /></p>
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<p>Notwithstanding that it’s not optimized, Listing 36.1 is reasonably fast. If you run Listing 36.2 (a sample line-drawing program that you can use to test-drive Listing 36.1), you may be as surprised as I was at how quickly the screen fills with vectors, considering that Listing 36.1 is entirely in C and has some redundant divides. Or perhaps you won’t be surprised—in which case I suggest you <i>not</i> miss the next chapter.</p>
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<p><b>LISTING 36.2 L36-2.C</b></p><!-- CODE //-->
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<pre>
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/* Sample line-drawing program. Uses the optimized
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line-drawing functions coded in LListing L36.1.C.
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Tested with Borland C++ in the small model. */
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#include <dos.h>
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#define GRAPHICS_MODE 0x13
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#define TEXT_MODE 0x03
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#define BIOS_VIDEO_INT 0x10
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#define X_MAX 320 /* working screen width */
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#define Y_MAX 200 /* working screen height */
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extern void LineDraw(int XStart, int YStart, int XEnd, int YEnd, int Color);
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/* Subroutine to draw a rectangle full of vectors, of the specified
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* length and color, around the specified rectangle center. */
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void VectorsUp(XCenter, YCenter, XLength, YLength, Color)
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int XCenter, YCenter; /* center of rectangle to fill */
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int XLength, YLength; /* distance from center to edge of rectangle */
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int Color; /* color to draw lines in */
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{
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int WorkingX, WorkingY;
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/* lines from center to top of rectangle */
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WorkingX = XCenter - XLength;
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WorkingY = YCenter - YLength;
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for ( ; WorkingX < ( XCenter + XLength ); WorkingX++ )
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{
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LineDraw(XCenter, YCenter, WorkingX, WorkingY, Color);
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}
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/* lines from center to right of rectangle */
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WorkingX = XCenter + XLength - 1;
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WorkingY = YCenter - YLength;
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for ( ; WorkingY < ( YCenter + YLength ); WorkingY++ )
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{
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LineDraw(XCenter, YCenter, WorkingX, WorkingY, Color);
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}
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/* lines from center to bottom of rectangle */
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WorkingX = XCenter + XLength - 1;
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WorkingY = YCenter + YLength - 1;
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for ( ; WorkingX >= ( XCenter - XLength ); WorkingX-- )
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{
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LineDraw(XCenter, YCenter, WorkingX, WorkingY, Color);
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}
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/* lines from center to left of rectangle */
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WorkingX = XCenter - XLength;
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WorkingY = YCenter + YLength - 1;
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for ( ; WorkingY >= ( YCenter - YLength ); WorkingY-- )
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{
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LineDraw(XCenter, YCenter, WorkingX, WorkingY, Color);
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}
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}
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/* Sample program to draw four rectangles full of lines. */
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int main()
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{
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union REGS regs;
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/* Set graphics mode */
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regs.x.ax = GRAPHICS_MODE;
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int86(BIOS_VIDEO_INT, &regs, &regs);
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/* Draw each of four rectangles full of vectors */
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VectorsUp(X_MAX / 4, Y_MAX / 4, X_MAX / 4, Y_MAX / 4, 1);
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VectorsUp(X_MAX * 3 / 4, Y_MAX / 4, X_MAX / 4, Y_MAX / 4, 2);
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VectorsUp(X_MAX / 4, Y_MAX * 3 / 4, X_MAX / 4, Y_MAX / 4, 3);
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VectorsUp(X_MAX * 3 / 4, Y_MAX * 3 / 4, X_MAX / 4, Y_MAX / 4, 4);
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/* Wait for a key to be pressed */
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getch();
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/* Return back to text mode */
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regs.x.ax = TEXT_MODE;
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int86(BIOS_VIDEO_INT, &regs, &regs);
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}
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</pre><!-- END CODE //-->
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<p><br /></p>
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<center>
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<table border="1">
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<tr>
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<td><a href="36-03.html">Previous</a></td>
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<td><a href="index.html">Table of Contents</a></td>
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<td><a href="37-01.html">Next</a></td>
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</tr>
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</table>
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</center>
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<hr width="90%" size="1" noshade="noshade" />
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<div align="center">
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Graphics Programming Black Book © 2001 Michael Abrash
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