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+**LISTING 50.4 POLYGON.H**
+
+    /* POLYGON.H: Header file for polygon-filling code, also includes
+       a number of useful items for 3-D animation. */
+
+    #define MAX_POLY_LENGTH 4  /* four vertices is the max per poly */
+    #define SCREEN_WIDTH 320
+    #define SCREEN_HEIGHT 240
+    #define PAGE0_START_OFFSET 0
+    #define PAGE1_START_OFFSET (((long)SCREEN_HEIGHT*SCREEN_WIDTH)/4)
+    /* Ratio: distance from viewpoint to projection plane / width of
+       projection plane. Defines the width of the field of view. Lower
+       absolute values = wider fields of view; higher values = narrower */
+    #define PROJECTION_RATIO   -2.0 /* negative because visible Z
+                                       coordinates are negative */
+    /* Draws the polygon described by the point list PointList in color
+       Color with all vertices offset by (X,Y) */
+    #define DRAW_POLYGON(PointList,NumPoints,Color,X,Y)         \
+       Polygon.Length = NumPoints;                              \
+       Polygon.PointPtr = PointList;                            \
+       FillConvexPolygon(&Polygon, Color, X, Y);
+
+    /* Describes a single 2-D point */
+    struct Point {
+       int X;   /* X coordinate */
+       int Y;   /* Y coordinate */
+    };
+    /* Describes a single 3-D point in homogeneous coordinates */
+    struct Point3 {
+       double X;   /* X coordinate */
+       double Y;   /* Y coordinate */
+       double Z;   /* Z coordinate */
+       double W;
+    };
+    /* Describes a series of points (used to store a list of vertices that
+       describe a polygon; each vertex is assumed to connect to the two
+       adjacent vertices, and the last vertex is assumed to connect to the
+       first) */
+    struct PointListHeader {
+       int Length;                /* # of points */
+       struct Point * PointPtr;   /* pointer to list of points */
+    };
+
+    /* Describes the beginning and ending X coordinates of a single
+       horizontal line */
+    struct HLine {
+       int XStart; /* X coordinate of leftmost pixel in line */
+       int XEnd;   /* X coordinate of rightmost pixel in line */
+    };
+
+    /* Describes a Length-long series of horizontal lines, all assumed to
+       be on contiguous scan lines starting at YStart and proceeding
+       downward (used to describe a scan-converted polygon to the
+       low-level hardware-dependent drawing code) */
+    struct HLineList {
+       int Length;                /* # of horizontal lines */
+       int YStart;                /* Y coordinate of topmost line */
+       struct HLine * HLinePtr;   /* pointer to list of horz lines */
+    };
+    struct Rect { int Left, Top, Right, Bottom; };
+
+    extern void XformVec(double Xform[4][4], double * SourceVec,
+       double * DestVec);
+    extern void ConcatXforms(double SourceXform1[4][4],
+       double SourceXform2[4][4], double DestXform[4][4]);
+    extern void XformAndProjectPoly(double Xform[4][4],
+       struct Point3 * Poly, int PolyLength, int Color);
+    extern int FillConvexPolygon(struct PointListHeader *, int, int, int);
+    extern void Set320x240Mode(void);
+    extern void ShowPage(unsigned int StartOffset);
+    extern void FillRectangleX(int StartX, int StartY, int EndX,
+       int EndY, unsigned int PageBase, int Color);
+    extern int DisplayedPage, NonDisplayedPage;
+    extern struct Rect EraseRect[];
+
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+* * * * *
+
+Graphics Programming Black Book © 2001 Michael Abrash