abrash-black-book/50-05.html
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<META name=vsisbn content="1576101746">
<META name=vstitle content="Michael Abrash's Graphics Programming Black Book, Special Edition">
<META name=vsauthor content="Michael Abrash">
<META name=vspublisher content="The Coriolis Group">
<META name=vspubdate content="07/01/97">
<META name=vscategory content="Web and Software Development: Game Development,Web and Software Development: Graphics and Multimedia Development">
<TITLE>Michael Abrash's Graphics Programming Black Book Special Edition: Adding a Dimension</TITLE>
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<P><B>LISTING 50.4 POLYGON.H</B></P>
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<PRE>
/* 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(&ampPolygon, 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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<font face="Verdana,sans-serif" size="1">Graphics Programming Black Book &copy; 2001 Michael Abrash</font>
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