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RGV.C
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C/C++ Source or Header
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1992-02-25
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6KB
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282 lines
/*
* rgv.c by Quincey Koziol for NCSA
*
* graphics routines for drawing on EGA
* Input coordinate space = 0..4095 by 0..4095
* MUST BE COMPILED WITH LARGE MEMORY MODEL!
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <dos.h> /* used for VGA init call */
#include "externs.h"
#define TRUE 1
#define FALSE 0
#define INXMAX 4096
#define INXSHIFT 12
#define INYMAX 4096
#define INYSHIFT 12
#define SCRNXHI 639
#define SCRNYHI 479
#define VGAxmax 640 /* max. number of pixels in the x direction */
#define VGAymax 480 /* max. number of pixels in the y direction */
#define VGAbytes 80 /* number of bytes per line */
#define MAXRW 32 /* max. number of real windows */
static int VGAactive; /* number of currently EGAactive window */
static char *VGAname="Video Graphics Array, 640 x 480";
/* Current status of an VGA window */
struct VGAWIN {
char inuse; /* true if window in use */
int pencolor, rotation, size;
int winbot,winleft,wintall,winwide;
/* position of the window in virtual space */
};
static struct VGAWIN VGAwins[MAXRW];
/*
Set up a new window; return its number.
Returns -1 if cannot create window.
*/
int RGVnewwin(void)
{
int w=0;
while(w<MAXRW && VGAwins[w].inuse)
w++;
if(w==MAXRW)
return(-1); /* no windows available */
VGAwins[w].pencolor=7;
VGAwins[w].winbot=0;
VGAwins[w].wintall=4096;
VGAwins[w].winleft=0;
VGAwins[w].winwide=4096;
VGAwins[w].inuse=TRUE;
return(w);
}
/*
Clear the screen.
*/
void RGVclrscr(int w)
{
if(w==VGAactive)
n_gmode(18);
}
void RGVclose(int w)
{
if(VGAactive==w) {
RGVclrscr(w);
VGAactive=-1;
}
VGAwins[w].inuse=FALSE;
}
/* set pixel at location (x,y) -- no range checking performed */
void RGVpoint(int w,int x,int y)
{
int x2,y2; /* on-screen coordinates */
if(w==VGAactive) {
x2=(int)((VGAxmax*(long)x)>>INXSHIFT);
y2=SCRNYHI-(int)(((long)y*VGAymax)>>INYSHIFT);
VGAset(x2,y2,VGAwins[w].pencolor);
}
}
/* draw a line from (x0,y0) to (x1,y1) */
/* uses Bresenham's Line Algorithm */
void RGVdrawline(int w,int x0,int y0,int x1,int y1)
{
int x,y,dx,dy,d,temp,
dx2,dy2, /* 2dx and 2dy */
direction; /* +1 or -1, used for slope */
char transpose; /* true if switching x and y for vertical-ish line */
#ifdef DEBUG
printf("RGVdrawline(): x0=%d, y0%d\n",x0,y0);
printf("x1=%d, y1=%d\n",x1,y1);
#endif
if(w!=VGAactive)
return;
x0=(int)(((long)x0*VGAxmax)>>INXSHIFT);
y0=VGAymax-1-(int)((VGAymax*(long)y0)>>INYSHIFT);
x1=(int)(((long)x1*VGAxmax)>>INXSHIFT);
y1=VGAymax-1-(int)((VGAymax*(long)y1)>>INYSHIFT);
if(abs(y1-y0)>abs(x1-x0)) { /* transpose vertical-ish to horizontal-ish */
temp=x1;
x1=y1;
y1=temp;
temp=x0;
x0=y0;
y0=temp;
transpose=TRUE;
}
else
transpose=FALSE;
/* make sure line is left to right */
if(x1<x0) {
temp=x1;
x1=x0;
x0=temp;
temp=y1;
y1=y0;
y0=temp;
}
/* SPECIAL CASE: 1 POINT */
if(x1==x0 && y1==y0) {
VGAset(x1,y1,VGAwins[w].pencolor);
return;
}
/* ANY LINE > 1 POINT */
x=x0;
y=y0;
dx=x1-x0;
if(y1>=y0) {
dy=y1-y0;
direction=1;
}
else {
dy=y0-y1;
direction=-1;
}
dx2=dx<<1;
dy2=dy<<1;
d=(dy<<1)-dx;
if(transpose) { /* CASE OF VERTICALISH (TRANSPOSED) LINES */
while(x<=x1) {
if(y>=0 && y< VGAxmax && x>=0 && x<VGAymax)
VGAset(y,x,VGAwins[w].pencolor);
while(d>=0) {
y+=direction;
d-=dx2;
}
d+=dy2;
x++;
}
}
else { /* CASE OF HORIZONTALISH LINES */
while(x<=x1) {
if(x>=0 && x<VGAxmax && y>=0 && y<VGAymax)
VGAset(x,y,VGAwins[w].pencolor);
while(d>=0) {
y+=direction;
d-=dx2;
}
d+=dy2;
x++;
}
} /* end horizontalish */
} /* end RGVdrawline() */
/*
Do whatever has to be done when the drawing is all done.
(For printers, that means eject page.)
*/
void RGVpagedone(int w)
{
/* do nothing for VGA */
w=w;
}
/*
Copy 'count' bytes of data to screen starting at current
cursor location.
*/
void RGVdataline(int w,char *data,int count)
{
/* Function not supported yet. */
w=w;
data=data;
count=count;
}
/*
Change pen color to the specified color.
*/
void RGVpencolor(int w,int color)
{
if(!color)
color=1;
color&=0x7;
/* flip color scale */
VGAwins[w].pencolor=8-color;
}
/*
Set description of future device-supported graphtext.
Rotation=quadrant.
*/
void RGVcharmode(int w,int rotation,int size)
{
/* No rotatable device-supported graphtext is available on VGA. */
w=w;
rotation=rotation;
size=size;
}
/* Not yet supported: */
void RGVshowcur(void) {}
void RGVlockcur(void) {}
void RGVhidecur(void) {}
/* Ring bell in window w */
void RGVbell(int w)
{
if(w==VGAactive)
putchar(7);
}
/* return name of device that this RG supports */
char *RGVdevname(void )
{
return(VGAname);
}
/*
Make this window visible, hiding all others.
Caller should follow this with clrscr and redraw to show the current
contents of the window.
*/
void RGVuncover(int w)
{
VGAactive=w;
}
/* initialize all RGV variables */
void RGVinit(void)
{
int i;
for(i=0; i<MAXRW; i++)
VGAwins[i].inuse = FALSE;
VGAactive=-1;
}
void RGVinfo(int w,int a,int b,int c,int d,int v)
{
w=w;
a=a;
b=b;
c=c;
d=d;
v=v;
}
/* go into VGA graphics mode */
void RGVgmode(void )
{
n_gmode(18);
}
/* go into VGA 80x25 color text mode */
void RGVtmode(void)
{
n_gmode(3);
VGAactive=-1;
}