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Amiga ACS 1998 #6
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descent
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poly.c
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1998-06-08
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/*
THE COMPUTER CODE CONTAINED HEREIN IS THE SOLE PROPERTY OF PARALLAX
SOFTWARE CORPORATION ("PARALLAX"). PARALLAX, IN DISTRIBUTING THE CODE TO
END-USERS, AND SUBJECT TO ALL OF THE TERMS AND CONDITIONS HEREIN, GRANTS A
ROYALTY-FREE, PERPETUAL LICENSE TO SUCH END-USERS FOR USE BY SUCH END-USERS
IN USING, DISPLAYING, AND CREATING DERIVATIVE WORKS THEREOF, SO LONG AS
SUCH USE, DISPLAY OR CREATION IS FOR NON-COMMERCIAL, ROYALTY OR REVENUE
FREE PURPOSES. IN NO EVENT SHALL THE END-USER USE THE COMPUTER CODE
CONTAINED HEREIN FOR REVENUE-BEARING PURPOSES. THE END-USER UNDERSTANDS
AND AGREES TO THE TERMS HEREIN AND ACCEPTS THE SAME BY USE OF THIS FILE.
COPYRIGHT 1993-1998 PARALLAX SOFTWARE CORPORATION. ALL RIGHTS RESERVED.
*/
/*
* $Source: f:/miner/source/2d/rcs/poly.c $
* $Revision: 1.5 $
* $Author: john $
* $Date: 1994/11/13 13:03:43 $
*
* Graphical routines for drawing polygons.
*
* $Log: poly.c $
* Revision 1.5 1994/11/13 13:03:43 john
* Added paged out bit in bitmap structure. Commented out the
* poly code that is never used.
*
* Revision 1.4 1994/03/14 16:56:13 john
* Changed grs_bitmap structure to include bm_flags.
*
* Revision 1.3 1993/10/15 16:23:14 john
* y
*
* Revision 1.2 1993/10/08 14:30:39 john
* *** empty log message ***
*
* Revision 1.1 1993/09/08 11:44:13 john
* Initial revision
*
*
*/
#include "mem.h"
#include "gr.h"
#include "grdef.h"
//#define USE_POLY_CODE 1
#define MAX_SCAN_LINES 1200
#ifdef USE_POLY_CODE
int y_edge_list[MAX_SCAN_LINES];
void gr_upoly(int nverts, int *vert )
{
int temp;
int startx, stopx; // X coordinates of both ends of current edge.
int firstx, firsty; // Saved copy of the first vertex to connect later.
int dx_dy; // Slope of current edge.
int miny, maxy;
int starty, stopy; // Y coordinates of both ends of current edge.
int x1, x2, i;
// Find the min and max rows to clear out the minimun y_edge_list.
// (Is it worth it?)
maxy = vert[1];
miny = vert[1];
for (i=3; i<(nverts*2); i+=2 )
{
if (vert[i]>maxy) maxy=vert[i];
if (vert[i]<miny) miny=vert[i];
}
miny >>= 16;
miny--; // -1 to be safe
maxy >>= 16;
maxy++; // +1 to be safe
// Clear only the part of the y_edge_list that w will be using
if (miny < 0) miny = 0;
if (maxy > MAX_SCAN_LINES) maxy = MAX_SCAN_LINES;
for (i=miny; i<maxy; i++ )
y_edge_list[i] = -1;
// Save the first vertex so that we can connect to it at the end.
firstx = vert[0];
firsty = vert[1] >> 16;
do
{
nverts--;
// Get the beginning coordinates of the current edge.
startx = vert[0];
starty = vert[1] >> 16;
// Get the ending coordinates of the current edge.
if (nverts > 0 ) {
stopx = vert[2];
stopy = vert[3] >> 16;
vert += 2;
} else {
stopx = firstx; // Last edge, uses first vertex as endpoint
stopy = firsty;
}
if (stopy < starty ) {
temp = stopy;
stopy = starty;
starty = temp;
temp = stopx;
stopx = startx;
startx = temp;
}
if (stopy == starty )
{
// Draw a edge going horizontally across screen
x1 = startx>>16;
x2 = stopx>>16;
if (x2 > x1 )
//gr_uscanline( x1, x2-1, stopy );
gr_uscanline( x1, x2, stopy );
else
//gr_uscanline( x2, x1-1, stopy );
gr_uscanline( x2, x1, stopy );
} else {
dx_dy = (stopx - startx) / (stopy - starty);
for (; starty < stopy; starty++ )
{
if (y_edge_list[starty]==-1)
y_edge_list[starty] = startx;
else {
x1 = y_edge_list[starty]>>16;
x2 = startx>>16;
if (x2 > x1 )
//gr_uscanline( x1, x2-1, starty );
gr_uscanline( x1, x2, starty );
else
//gr_uscanline( x2, x1-1, starty );
gr_uscanline( x2, x1, starty );
}
startx += dx_dy;
}
}
} while (nverts > 0);
}
void gr_poly(int nverts, int *vert )
{
int temp;
int startx, stopx; // X coordinates of both ends of current edge.
int firstx, firsty; // Saved copy of the first vertex to connect later.
int dx_dy; // Slope of current edge.
int miny, maxy;
int starty, stopy; // Y coordinates of both ends of current edge.
int x1, x2, i, j;
// Find the min and max rows to clear out the minimun y_edge_list.
// (Is it worth it?)
maxy = vert[1];
miny = vert[1];
j = 0;
for (i=3; i<(nverts*2); i+=2 )
{
if (vert[i]>maxy) {
if ((maxy=vert[i]) > MAXY) j++;
//if (j>1) break;
}
if (vert[i]<miny) {
if ((miny=vert[i]) < MINY) j++;
//if (j>1) break;
}
}
miny >>= 16;
miny--; // -1 to be safe
maxy >>= 16;
maxy++; // +1 to be safe
if (miny < MINY) miny = MINY;
if (maxy > MAXY) maxy = MAXY+1;
// Clear only the part of the y_edge_list that w will be using
for (i=miny; i<maxy; i++ )
y_edge_list[i] = -1;
// Save the first vertex so that we can connect to it at the end.
firstx = vert[0];
firsty = vert[1] >> 16;
do
{
nverts--;
// Get the beginning coordinates of the current edge.
startx = vert[0];
starty = vert[1] >> 16;
// Get the ending coordinates of the current edge.
if (nverts > 0 ) {
stopx = vert[2];
stopy = vert[3] >> 16;
vert += 2;
} else {
stopx = firstx; // Last edge, uses first vertex as endpoint
stopy = firsty;
}
if (stopy < starty ) {
temp = stopy;
stopy = starty;
starty = temp;
temp = stopx;
stopx = startx;
startx = temp;
}
if (stopy == starty )
{
// Draw a edge going horizontally across screen
if ((stopy >= MINY) && (stopy <=MAXY )) {
x1 = startx>>16;
x2 = stopx>>16;
if (x1 > x2 ) {
temp = x2;
x2 = x1;
x1 = temp;
}
if ((x1 <= MAXX ) && (x2 >= MINX))
{
if (x1 < MINX ) x1 = MINX;
if (x2 > MAXX ) x2 = MAXX+1;
//gr_uscanline( x1, x2-1, stopy );
gr_scanline( x1, x2, stopy );
}
}
} else {
dx_dy = (stopx - startx) / (stopy - starty);
if (starty < MINY ) {
startx = dx_dy*(MINY-starty)+startx;
starty = MINY;
}
if (stopy > MAXY ) {
stopx = dx_dy*(MAXY-starty)+startx;
stopy = MAXY+1;
}
for (; starty < stopy; starty++ )
{ if (y_edge_list[starty]==-1)
y_edge_list[starty] = startx;
else {
x1 = y_edge_list[starty]>>16;
x2 = startx>>16;
if (x1 > x2 ) {
temp = x2;
x2 = x1;
x1 = temp;
}
if ((x1 <= MAXX ) && (x2 >= MINX))
{
if (x1 < MINX ) x1 = MINX;
if (x2 > MAXX ) x2 = MAXX+1;
//gr_uscanline( x1, x2-1, starty );
gr_scanline( x1, x2, starty );
}
}
startx += dx_dy;
}
}
} while (nverts > 0);
}
#endif