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