229 lines
5.2 KiB
C
229 lines
5.2 KiB
C
/* $Id: clipper.c,v 1.5 2002-10-03 03:46:34 btb Exp $ */
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/*
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THE COMPUTER CODE CONTAINED HEREIN IS THE SOLE PROPERTY OF PARALLAX
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SOFTWARE CORPORATION ("PARALLAX"). PARALLAX, IN DISTRIBUTING THE CODE TO
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END-USERS, AND SUBJECT TO ALL OF THE TERMS AND CONDITIONS HEREIN, GRANTS A
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ROYALTY-FREE, PERPETUAL LICENSE TO SUCH END-USERS FOR USE BY SUCH END-USERS
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IN USING, DISPLAYING, AND CREATING DERIVATIVE WORKS THEREOF, SO LONG AS
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SUCH USE, DISPLAY OR CREATION IS FOR NON-COMMERCIAL, ROYALTY OR REVENUE
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FREE PURPOSES. IN NO EVENT SHALL THE END-USER USE THE COMPUTER CODE
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CONTAINED HEREIN FOR REVENUE-BEARING PURPOSES. THE END-USER UNDERSTANDS
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AND AGREES TO THE TERMS HEREIN AND ACCEPTS THE SAME BY USE OF THIS FILE.
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COPYRIGHT 1993-1998 PARALLAX SOFTWARE CORPORATION. ALL RIGHTS RESERVED.
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*/
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#ifdef HAVE_CONFIG_H
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#include <conf.h>
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#endif
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#include "3d.h"
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#include "globvars.h"
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#include "clipper.h"
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#include "error.h"
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int free_point_num=0;
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g3s_point temp_points[MAX_POINTS_IN_POLY];
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g3s_point *free_points[MAX_POINTS_IN_POLY];
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void init_free_points(void)
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{
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int i;
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for (i=0;i<MAX_POINTS_IN_POLY;i++)
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free_points[i] = &temp_points[i];
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}
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g3s_point *get_temp_point()
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{
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g3s_point *p;
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Assert (free_point_num < MAX_POINTS_IN_POLY );
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p = free_points[free_point_num++];
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p->p3_flags = PF_TEMP_POINT;
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return p;
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}
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void free_temp_point(g3s_point *p)
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{
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Assert(p->p3_flags & PF_TEMP_POINT);
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free_points[--free_point_num] = p;
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p->p3_flags &= ~PF_TEMP_POINT;
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}
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//clips an edge against one plane.
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g3s_point *clip_edge(int plane_flag,g3s_point *on_pnt,g3s_point *off_pnt)
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{
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fix psx_ratio;
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fix a,b,kn,kd;
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g3s_point *tmp;
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//compute clipping value k = (xs-zs) / (xs-xe-zs+ze)
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//use x or y as appropriate, and negate x/y value as appropriate
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if (plane_flag & (CC_OFF_RIGHT | CC_OFF_LEFT)) {
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a = on_pnt->p3_x;
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b = off_pnt->p3_x;
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}
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else {
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a = on_pnt->p3_y;
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b = off_pnt->p3_y;
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}
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if (plane_flag & (CC_OFF_LEFT | CC_OFF_BOT)) {
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a = -a;
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b = -b;
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}
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kn = a - on_pnt->p3_z; //xs-zs
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kd = kn - b + off_pnt->p3_z; //xs-zs-xe+ze
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tmp = get_temp_point();
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psx_ratio = fixdiv( kn, kd );
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// PSX_HACK!!!!
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// tmp->p3_x = on_pnt->p3_x + fixmuldiv(off_pnt->p3_x-on_pnt->p3_x,kn,kd);
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// tmp->p3_y = on_pnt->p3_y + fixmuldiv(off_pnt->p3_y-on_pnt->p3_y,kn,kd);
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tmp->p3_x = on_pnt->p3_x + fixmul( (off_pnt->p3_x-on_pnt->p3_x), psx_ratio);
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tmp->p3_y = on_pnt->p3_y + fixmul( (off_pnt->p3_y-on_pnt->p3_y), psx_ratio);
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if (plane_flag & (CC_OFF_TOP|CC_OFF_BOT))
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tmp->p3_z = tmp->p3_y;
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else
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tmp->p3_z = tmp->p3_x;
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if (plane_flag & (CC_OFF_LEFT|CC_OFF_BOT))
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tmp->p3_z = -tmp->p3_z;
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if (on_pnt->p3_flags & PF_UVS) {
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// PSX_HACK!!!!
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// tmp->p3_u = on_pnt->p3_u + fixmuldiv(off_pnt->p3_u-on_pnt->p3_u,kn,kd);
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// tmp->p3_v = on_pnt->p3_v + fixmuldiv(off_pnt->p3_v-on_pnt->p3_v,kn,kd);
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tmp->p3_u = on_pnt->p3_u + fixmul((off_pnt->p3_u-on_pnt->p3_u), psx_ratio);
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tmp->p3_v = on_pnt->p3_v + fixmul((off_pnt->p3_v-on_pnt->p3_v), psx_ratio);
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tmp->p3_flags |= PF_UVS;
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}
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if (on_pnt->p3_flags & PF_LS) {
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// PSX_HACK
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// tmp->p3_r = on_pnt->p3_r + fixmuldiv(off_pnt->p3_r-on_pnt->p3_r,kn,kd);
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// tmp->p3_g = on_pnt->p3_g + fixmuldiv(off_pnt->p3_g-on_pnt->p3_g,kn,kd);
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// tmp->p3_b = on_pnt->p3_b + fixmuldiv(off_pnt->p3_b-on_pnt->p3_b,kn,kd);
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tmp->p3_l = on_pnt->p3_l + fixmul((off_pnt->p3_l-on_pnt->p3_l), psx_ratio);
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tmp->p3_flags |= PF_LS;
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}
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g3_code_point(tmp);
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return tmp;
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}
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//clips a line to the viewing pyramid.
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void clip_line(g3s_point **p0,g3s_point **p1,ubyte codes_or)
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{
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int plane_flag;
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g3s_point *old_p1;
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//might have these left over
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(*p0)->p3_flags &= ~(PF_UVS|PF_LS);
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(*p1)->p3_flags &= ~(PF_UVS|PF_LS);
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for (plane_flag=1;plane_flag<16;plane_flag<<=1)
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if (codes_or & plane_flag) {
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if ((*p0)->p3_codes & plane_flag)
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{g3s_point *t=*p0; *p0=*p1; *p1=t;} //swap!
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old_p1 = *p1;
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*p1 = clip_edge(plane_flag,*p0,*p1);
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if (old_p1->p3_flags & PF_TEMP_POINT)
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free_temp_point(old_p1);
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}
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}
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int clip_plane(int plane_flag,g3s_point **src,g3s_point **dest,int *nv,g3s_codes *cc)
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{
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int i;
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g3s_point **save_dest=dest;
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//copy first two verts to end
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src[*nv] = src[0];
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src[*nv+1] = src[1];
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cc->and = 0xff; cc->or = 0;
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for (i=1;i<=*nv;i++) {
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if (src[i]->p3_codes & plane_flag) { //cur point off?
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if (! (src[i-1]->p3_codes & plane_flag)) { //prev not off?
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*dest = clip_edge(plane_flag,src[i-1],src[i]);
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cc->or |= (*dest)->p3_codes;
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cc->and &= (*dest)->p3_codes;
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dest++;
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}
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if (! (src[i+1]->p3_codes & plane_flag)) {
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*dest = clip_edge(plane_flag,src[i+1],src[i]);
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cc->or |= (*dest)->p3_codes;
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cc->and &= (*dest)->p3_codes;
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dest++;
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}
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//see if must free discarded point
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if (src[i]->p3_flags & PF_TEMP_POINT)
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free_temp_point(src[i]);
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}
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else { //cur not off, copy to dest buffer
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*dest++ = src[i];
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cc->or |= src[i]->p3_codes;
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cc->and &= src[i]->p3_codes;
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}
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}
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return (dest-save_dest);
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}
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g3s_point **clip_polygon(g3s_point **src,g3s_point **dest,int *nv,g3s_codes *cc)
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{
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int plane_flag;
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g3s_point **t;
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for (plane_flag=1;plane_flag<16;plane_flag<<=1)
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if (cc->or & plane_flag) {
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*nv = clip_plane(plane_flag,src,dest,nv,cc);
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if (cc->and) //clipped away
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return dest;
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t = src; src = dest; dest = t;
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}
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return src; //we swapped after we copied
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}
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