Programmer 7500/MAX_PROGRAMMERS.iso/CLIPPER/MISC/MSMOUSE1.ZIP/EGA.ZIP/MOVE.ZIP/SNOW.C

C/C++ Source or Header | 1989-02-10 | 5.1 KB | 201 lines

/*------------------------------------------------------------------
 *  SNOW.C
 *
 *  Demonstrates mouse functions and EGA animation
 *  Reads and writes palette information using EGA Register Interface
 *
 *  C 5.1 Make File:
 *
 *      snow.exe: snow.c
 *        cl snow.c
 *
 *   QuickC Program List:
 *
 *      SNOW.C
 *
 *--------------------------------------------------------------------*/

#include <bios.h>
#include <graph.h>
#include <dos.h>
#include <stdio.h>
#include <stdlib.h>

#define MOUSE 0x33
#define VIDEO 0x10

void delay( int );
void DrawTree( int, int );

#define MAXFLAKES 150
#define MAXTREES 30

char far paltable[16];

main ()
{
    union REGS inregs, outregs;
    struct SREGS segregs;
    unsigned int i, color, x, y, ystep;
    int bound_rand (int);

    _setvideomode( _ERESCOLOR );            /* EGA 640x350 16 color */

    inregs.x.ax = 0;                        /* Reset mouse */
    int86 (MOUSE, &inregs, &outregs);

    for (i = 0; i < MAXTREES; i++ )         /* Draw the forest */
        {
        x = bound_rand(639);
        y = 299 * i / MAXTREES + 50;
        DrawTree( x, y );
        }

    for (i = 0; i < MAXFLAKES; i++)         /* Create snowflake trails */
        {
        x = bound_rand (639);
        y = 0;
        ystep = bound_rand(3) + 1;
        color = bound_rand(10) + 5;
        do
            {
            inregs.x.cx = x;
            inregs.x.dx = y;
            inregs.h.al = color++;
            inregs.h.bh = 0;
            inregs.h.ah = 0x0c;             /* Write graphics pixel */
            int86 (VIDEO, &inregs, &outregs);

            color = color & 0x0f;           /* Rotate color 5 to 15 */
            if (!color)
                color = 5;
            x += bound_rand(6) - 3;
            y += ystep;
            } while ((y < 350) && (x >= 0) && (x < 640));
        }

    paltable[0] = 0;                        /* Colors 0 to 4 stay constant */
    paltable[1] = 1;
    paltable[2] = 2;
    paltable[3] = 0x3c;
    paltable[4] = 0x3f;
    for (i = 5; i < 16; i++)                /* Set colors 5 to 15 to 0 */
        paltable[i] = 0;
    color = 5;
    do
        {
        paltable[color] = 0x3f;             /* one color entry to white */
        inregs.h.ah = 0xf3;
        inregs.x.cx = 0x0010;
        inregs.x.dx = 0x18;
        segregs.es = (unsigned int)(((unsigned long)paltable >> 16) & 0xffff);
        inregs.x.bx = (unsigned int)(((unsigned long)paltable) & 0xffff);

    /* Make sure not in vertical retrace */
        while (inp(0x3da) & 8)
            ;

        /* Wait for beginning of vertical retrace */
        while (!(inp(0x3da) & 8))
            ;

        /* Make the palette register changes */
        int86x (VIDEO, &inregs, &outregs, &segregs);

        /* Assure EGA's ACR is pointing to AAR */
        inp (0x3da);

        /* Activate new palette */
        outp (0x3c0, 0x20);

        paltable[color++] = 0;              /* blacken this snowflake */
        color = color & 0x0f;
        if (!color)                         /* loop thru colors 5 to 15 */
            color = 5;

        delay( 1 );                         /* Delay for 1/18.2 seconds */

        do
            {
            inregs.x.ax = 3;                /* Get mouse status */
            int86 (MOUSE, &inregs, &outregs);

            /* Freeze while left button pressed */
            } while ((outregs.x.bx & 1));

        inregs.x.ax = 3;                    /* Get mouse status */
        int86 (MOUSE, &inregs, &outregs);

        /* loop until left mouse button is pressed */
        } while ((outregs.x.bx & 3) != 2 );

    inregs.x.ax = 2;                        /* Hide Mouse cursor */
    int86 (MOUSE, &inregs, &outregs);

    _clearscreen( _GCLEARSCREEN );
    _setvideomode( _DEFAULTMODE );
}

int bound_rand (bound)
int bound;
{
    int i;

    do
        {
        i = (int)((long)rand() * (bound+1) / 32767);
        } while (i == (bound+1));
    return (i);
}

#define BOX 16

void DrawTree( x, y )
int x, y;
{
    int i;

    /* fill in the trunk */
    _setcolor( 1 );
    _rectangle( _GFILLINTERIOR, x, y, x + BOX, y + BOX );

    /* outline the trunk */
    _setcolor( 3 );
    _rectangle( _GBORDER, x, y, x + BOX, y + BOX );

    /* put green needles on the tree */
    _setcolor( 2 );
    for ( i = x - BOX; i < x + 2 * BOX; i++ )
        {
        _moveto( i, y);
        _lineto( x + BOX / 2, y - 5 * BOX );
        }

    /* outline the branches */
    _setcolor( 4 );
    _moveto( x-BOX, y );
    _lineto( x+2*BOX, y );
    _lineto( x+BOX/2, y-5*BOX );
    _lineto( x-BOX, y );
}


/* Delay for a number of clock ticks */
void delay( ticks )
int ticks;
{
    long end_tick, now_tick;
    unsigned midnight_flag;

    _bios_timeofday( _TIME_GETCLOCK, &now_tick );
    end_tick = now_tick + (long) ticks;

    do
        {
        midnight_flag = _bios_timeofday( _TIME_GETCLOCK, &now_tick );
        if (midnight_flag)
            end_tick -= 1573040;
        }
    while ( now_tick < end_tick );
}