105 lines
3.7 KiB
C++
105 lines
3.7 KiB
C++
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/* PLANETS.C--Example from chapters 4 and 7 of User's Guide */
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#include <graphics.h> /* For graphics library functions */
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#include <stdlib.h> /* For exit() */
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#include <stdio.h>
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#include <conio.h>
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int set_graph(void); /* Initialize graphics */
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void calc_coords(void); /* Scale distances onscreen */
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void draw_planets(void); /* Draw and fill planet circles */
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/* Draw one planet circle */
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void draw_planet(float x_pos, float radius,
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int color, int fill_style);
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void get_key(void); /* Display text on graphics screen, */
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/* wait for key */
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/* Global variables -- set by calc_coords() */
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int max_x, max_y; /* Maximum x- and y-coordinates */
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int y_org; /* Y-coordinate for all drawings */
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int au1; /* One astronomical unit in pixels
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(inner planets) */
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int au2; /* One astronomical unit in pixels
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(outer planets) */
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int erad; /* One earth radius in pixels */
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int main()
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{
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/* Exit if not EGA or VGA */
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/* Find out if they have what it takes */
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if (set_graph() != 1) {
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printf("This program requires EGA or VGA graphics\n");
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exit(0);
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}
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calc_coords(); /* Scale to graphics resolution in use */
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draw_planets(); /* Sun through Uranus (no room for others) */
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get_key(); /* Display message and wait for key press */
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closegraph(); /* Close graphics system */
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return 0;
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}
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int set_graph(void)
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{
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int graphdriver = DETECT, graphmode, error_code;
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/* Initialize graphics system; must be EGA or VGA */
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initgraph(&graphdriver, &graphmode, "..\\bgi");
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error_code = graphresult();
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if (error_code != grOk)
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return(-1); /* No graphics hardware found */
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if ((graphdriver != EGA) && (graphdriver != VGA))
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{
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closegraph();
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return 0;
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}
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return(1); /* Graphics OK, so return "true" */
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}
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void calc_coords(void)
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{
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/* Set global variables for drawing */
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max_x = getmaxx(); /* Returns maximum x-coordinate */
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max_y = getmaxy(); /* Returns maximum y-coordinate */
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y_org = max_y / 2; /* Set Y coord for all objects */
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erad = max_x / 200; /* One earth radius in pixels */
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au1 = erad * 20; /* Scale for inner planets */
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au2 = erad * 10; /* scale for outer planets */
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}
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void draw_planets()
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{
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/* Each call specifies x-coordinate in au, radius, and color */
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/* arc of Sun */
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draw_planet(-90, 100, EGA_YELLOW, EMPTY_FILL);
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/* Mercury */
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draw_planet(0.4 * au1, 0.4 * erad, EGA_BROWN, LTBKSLASH_FILL);
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/* Venus */
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draw_planet(0.7 * au1, 1.0 * erad, EGA_WHITE, SOLID_FILL);
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/* Earth */
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draw_planet(1.0 * au1, 1.0 * erad, EGA_LIGHTBLUE, SOLID_FILL);
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/* Mars */
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draw_planet(1.5 * au1, 0.4 * erad, EGA_LIGHTRED, CLOSE_DOT_FILL);
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/* Jupiter */
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draw_planet(5.2 * au2, 11.2 * erad, EGA_WHITE, LINE_FILL);
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/* Saturn */
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draw_planet(9.5 * au2, 9.4 * erad, EGA_LIGHTGREEN, LINE_FILL);
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/* Uranus */
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draw_planet(19.2 * au2, 4.2 * erad, EGA_GREEN, LINE_FILL);
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}
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void draw_planet(float x_pos, float radius, int color, int fill_style)
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{
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setcolor (color); /* This becomes drawing color */
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circle(x_pos, y_org, radius); /* Draw the circle */
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setfillstyle(fill_style, color); /* Set pattern to fill interior */
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floodfill(x_pos, y_org, color); /* Fill the circle */
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}
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void get_key(void)
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{
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outtextxy(50, max_y - 20, "Press any key to exit");
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getch();
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}
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