129 lines
5.2 KiB
Markdown
129 lines
5.2 KiB
Markdown
**LISTING 38.3 L38-3.C**
|
|
|
|
/* Sample program to exercise the polygon-filling routines. This code
|
|
and all polygon-filling code has been tested with Borland and
|
|
Microsoft compilers. */
|
|
|
|
#include <conio.h>
|
|
#include <dos.h>
|
|
#include "polygon.h"
|
|
|
|
/* Draws the polygon described by the point list PointList in color
|
|
Color with all vertices offset by (X,Y) */
|
|
#define DRAW_POLYGON(PointList,Color,X,Y) \
|
|
Polygon.Length = sizeof(PointList)/sizeof(struct Point); \
|
|
Polygon.PointPtr = PointList; \
|
|
FillConvexPolygon(&Polygon, Color, X, Y);
|
|
|
|
void main(void);
|
|
extern int FillConvexPolygon(struct PointListHeader *, int, int, int);
|
|
|
|
void main() {
|
|
int i, j;
|
|
struct PointListHeader Polygon;
|
|
static struct Point ScreenRectangle[] =
|
|
{{0,0},{320,0},{320,200},{0,200}};
|
|
static struct Point ConvexShape[] =
|
|
{{0,0},{121,0},{320,0},{200,51},{301,51},{250,51},{319,143},
|
|
{320,200},{22,200},{0,200},{50,180},{20,160},{50,140},
|
|
{20,120},{50,100},{20,80},{50,60},{20,40},{50,20}};
|
|
static struct Point Hexagon[] =
|
|
{{90,-50},{0,-90},{-90,-50},{-90,50},{0,90},{90,50}};
|
|
static struct Point Triangle1[] = {{30,0},{15,20},{0,0}};
|
|
static struct Point Triangle2[] = {{30,20},{15,0},{0,20}};
|
|
static struct Point Triangle3[] = {{0,20},{20,10},{0,0}};
|
|
static struct Point Triangle4[] = {{20,20},{20,0},{0,10}};
|
|
union REGS regset;
|
|
|
|
/* Set the display to VGA mode 13h, 320x200 256-color mode */
|
|
regset.x.ax = 0x0013; /* AH = 0 selects mode set function,
|
|
AL = 0x13 selects mode 0x13
|
|
when set as parameters for INT 0x10 */
|
|
int86(0x10, ®set, ®set);
|
|
|
|
/* Clear the screen to cyan */
|
|
DRAW_POLYGON(ScreenRectangle, 3, 0, 0);
|
|
|
|
/* Draw an irregular shape that meets our definition of convex but
|
|
is not convex by any normal description */
|
|
DRAW_POLYGON(ConvexShape, 6, 0, 0);
|
|
getch(); /* wait for a keypress */
|
|
|
|
/* Draw adjacent triangles across the top half of the screen */
|
|
for (j=0; j<=80; j+=20) {
|
|
for (i=0; i<290; i += 30) {
|
|
DRAW_POLYGON(Triangle1, 2, i, j);
|
|
DRAW_POLYGON(Triangle2, 4, i+15, j);
|
|
}
|
|
}
|
|
|
|
/* Draw adjacent triangles across the bottom half of the screen */
|
|
for (j=100; j<=170; j+=20) {
|
|
/* Do a row of pointing-right triangles */
|
|
for (i=0; i<290; i += 20) {
|
|
DRAW_POLYGON(Triangle3, 40, i, j);
|
|
}
|
|
/* Do a row of pointing-left triangles halfway between one row
|
|
of pointing-right triangles and the next, to fit between */
|
|
for (i=0; i<290; i += 20) {
|
|
DRAW_POLYGON(Triangle4, 1, i, j+10);
|
|
}
|
|
}
|
|
getch(); /* wait for a keypress */
|
|
|
|
/* Finally, draw a series of concentric hexagons of approximately
|
|
the same proportions in the center of the screen */
|
|
for (i=0; i<16; i++) {
|
|
DRAW_POLYGON(Hexagon, i, 160, 100);
|
|
for (j=0; j<sizeof(Hexagon)/sizeof(struct Point); j++) {
|
|
/* Advance each vertex toward the center */
|
|
if (Hexagon[j].X != 0) {
|
|
Hexagon[j].X -= Hexagon[j].X >= 0 ? 3 : -3;
|
|
Hexagon[j].Y -= Hexagon[j].Y >= 0 ? 2 : -2;
|
|
} else {
|
|
Hexagon[j].Y -= Hexagon[j].Y >= 0 ? 3 : -3;
|
|
}
|
|
}
|
|
}
|
|
getch(); /* wait for a keypress */
|
|
|
|
/* Return to text mode and exit */
|
|
regset.x.ax = 0x0003; /* AL = 3 selects 80x25 text mode */
|
|
int86(0x10, ®set, ®set);
|
|
}
|
|
|
|
**LISTING 38.4 POLYGON.H**
|
|
|
|
/* POLYGON.H: Header file for polygon-filling code */
|
|
|
|
/* Describes a single point (used for a single vertex) */
|
|
struct Point {
|
|
int X; /* X coordinate */
|
|
int Y; /* Y coordinate */
|
|
};
|
|
|
|
/* 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 */
|
|
};
|