WebSVN – Games.Descent – Blame – /common/3d/clipper.cpp

Rev	Author	Line No.	Line
1	pmbaty	1	/*
		2	* This file is part of the DXX-Rebirth project <https://www.dxx-rebirth.com/>.
		3	* It is copyright by its individual contributors, as recorded in the
		4	* project's Git history. See COPYING.txt at the top level for license
		5	* terms and a link to the Git history.
		6	*/
		7
		8	#include "3d.h"
		9	#include "globvars.h"
		10	#include "clipper.h"
		11	#include "dxxerror.h"
		12
		13	#include "compiler-range_for.h"
		14	#include <stdexcept>
		15
		16	namespace dcx {
		17
		18	#if !DXX_USE_OGL
		19	temporary_points_t::temporary_points_t() :
		20	free_point_num(0)
		21	{
		22	auto p = &temp_points.front();
		23	range_for (auto &f, free_points)
		24	f = p++;
		25	}
		26
		27	static g3s_point &get_temp_point(temporary_points_t &t)
		28	{
		29	if (t.free_point_num >= t.free_points.size())
		30	throw std::out_of_range("not enough free points");
		31	auto &p = *t.free_points[t.free_point_num++];
		32	p.p3_flags = PF_TEMP_POINT;
		33	return p;
		34	}
		35
		36	void temporary_points_t::free_temp_point(g3s_point *p)
		37	{
		38	if (!(p->p3_flags & PF_TEMP_POINT))
		39	throw std::invalid_argument("freeing non-temporary point");
		40	if (--free_point_num >= free_points.size())
		41	throw std::out_of_range("too many free points");
		42	free_points[free_point_num] = p;
		43	p->p3_flags &= ~PF_TEMP_POINT;
		44	}
		45
		46	//clips an edge against one plane.
		47	static g3s_point &clip_edge(int plane_flag,g3s_point on_pnt,g3s_point off_pnt, temporary_points_t &tp)
		48	{
		49	fix psx_ratio;
		50	fix a,b,kn,kd;
		51
		52	//compute clipping value k = (xs-zs) / (xs-xe-zs+ze)
		53	//use x or y as appropriate, and negate x/y value as appropriate
		54
		55	if (plane_flag & (CC_OFF_RIGHT \| CC_OFF_LEFT)) {
		56	a = on_pnt->p3_x;
		57	b = off_pnt->p3_x;
		58	}
		59	else {
		60	a = on_pnt->p3_y;
		61	b = off_pnt->p3_y;
		62	}
		63
		64	if (plane_flag & (CC_OFF_LEFT \| CC_OFF_BOT)) {
		65	a = -a;
		66	b = -b;
		67	}
		68
		69	kn = a - on_pnt->p3_z; //xs-zs
		70	kd = kn - b + off_pnt->p3_z; //xs-zs-xe+ze
		71
		72	auto &tmp = get_temp_point(tp);
		73
		74	psx_ratio = fixdiv( kn, kd );
		75	tmp.p3_x = on_pnt->p3_x + fixmul( (off_pnt->p3_x-on_pnt->p3_x), psx_ratio);
		76	tmp.p3_y = on_pnt->p3_y + fixmul( (off_pnt->p3_y-on_pnt->p3_y), psx_ratio);
		77
		78	if (plane_flag & (CC_OFF_TOP\|CC_OFF_BOT))
		79	tmp.p3_z = tmp.p3_y;
		80	else
		81	tmp.p3_z = tmp.p3_x;
		82
		83	if (plane_flag & (CC_OFF_LEFT\|CC_OFF_BOT))
		84	tmp.p3_z = -tmp.p3_z;
		85
		86	if (on_pnt->p3_flags & PF_UVS) {
		87	// PSX_HACK!!!!
		88	// tmp.p3_u = on_pnt->p3_u + fixmuldiv(off_pnt->p3_u-on_pnt->p3_u,kn,kd);
		89	// tmp.p3_v = on_pnt->p3_v + fixmuldiv(off_pnt->p3_v-on_pnt->p3_v,kn,kd);
		90	tmp.p3_u = on_pnt->p3_u + fixmul((off_pnt->p3_u-on_pnt->p3_u), psx_ratio);
		91	tmp.p3_v = on_pnt->p3_v + fixmul((off_pnt->p3_v-on_pnt->p3_v), psx_ratio);
		92
		93	tmp.p3_flags \|= PF_UVS;
		94	}
		95
		96	if (on_pnt->p3_flags & PF_LS) {
		97	// PSX_HACK
		98	// tmp.p3_r = on_pnt->p3_r + fixmuldiv(off_pnt->p3_r-on_pnt->p3_r,kn,kd);
		99	// tmp.p3_g = on_pnt->p3_g + fixmuldiv(off_pnt->p3_g-on_pnt->p3_g,kn,kd);
		100	// tmp.p3_b = on_pnt->p3_b + fixmuldiv(off_pnt->p3_b-on_pnt->p3_b,kn,kd);
		101	tmp.p3_l = on_pnt->p3_l + fixmul((off_pnt->p3_l-on_pnt->p3_l), psx_ratio);
		102	tmp.p3_flags \|= PF_LS;
		103	}
		104	g3_code_point(tmp);
		105	return tmp;
		106	}
		107
		108	//clips a line to the viewing pyramid.
		109	void clip_line(g3s_point &p0,g3s_point &p1,const uint_fast8_t codes_or, temporary_points_t &tp)
		110	{
		111	//might have these left over
		112	p0->p3_flags &= ~(PF_UVS\|PF_LS);
		113	p1->p3_flags &= ~(PF_UVS\|PF_LS);
		114
		115	for (int plane_flag=1;plane_flag<16;plane_flag<<=1)
		116	if (codes_or & plane_flag) {
		117
		118	if (p0->p3_codes & plane_flag)
		119	std::swap(p0, p1);
		120	const auto old_p1 = std::exchange(p1, &clip_edge(plane_flag,p0,p1,tp));
		121	if (old_p1->p3_flags & PF_TEMP_POINT)
		122	tp.free_temp_point(old_p1);
		123	}
		124	}
		125
		126	static int clip_plane(int plane_flag,polygon_clip_points &src,polygon_clip_points &dest,int nv,g3s_codes cc, temporary_points_t &tp)
		127	{
		128	//copy first two verts to end
		129	src[*nv] = src[0];
		130	src[*nv+1] = src[1];
		131
		132	cc->uand = 0xff; cc->uor = 0;
		133
		134	uint_fast32_t j = 0;
		135	for (int i=1;i<=*nv;i++) {
		136
		137	if (src[i]->p3_codes & plane_flag) { //cur point off?
		138
		139	if (! (src[i-1]->p3_codes & plane_flag)) { //prev not off?
		140
		141	dest[j] = &clip_edge(plane_flag,src[i-1],src[i],tp);
		142	cc->uor \|= dest[j]->p3_codes;
		143	cc->uand &= dest[j]->p3_codes;
		144	++j;
		145	}
		146
		147	if (! (src[i+1]->p3_codes & plane_flag)) {
		148
		149	dest[j] = &clip_edge(plane_flag,src[i+1],src[i],tp);
		150	cc->uor \|= dest[j]->p3_codes;
		151	cc->uand &= dest[j]->p3_codes;
		152	++j;
		153	}
		154
		155	//see if must free discarded point
		156
		157	if (src[i]->p3_flags & PF_TEMP_POINT)
		158	tp.free_temp_point(src[i]);
		159	}
		160	else { //cur not off, copy to dest buffer
		161
		162	dest[j++] = src[i];
		163
		164	cc->uor \|= src[i]->p3_codes;
		165	cc->uand &= src[i]->p3_codes;
		166	}
		167	}
		168	return j;
		169	}
		170
		171	const polygon_clip_points &clip_polygon(polygon_clip_points &rsrc,polygon_clip_points &rdest,int nv,g3s_codes cc, temporary_points_t &tp)
		172	{
		173	polygon_clip_points src = &rsrc, dest = &rdest;
		174	for (int plane_flag=1;plane_flag<16;plane_flag<<=1)
		175
		176	if (cc->uor & plane_flag) {
		177
		178	nv = clip_plane(plane_flag,src,*dest,nv,cc,tp);
		179
		180	if (cc->uand) //clipped away
		181	return *dest;
		182
		183	std::swap(src, dest);
		184	}
		185
		186	return *src; //we swapped after we copied
		187	}
		188	#endif
		189
		190	}

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Games.Descent /common/3d/clipper.cpp – Rev 1