/*
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.
*/
/*
 * 
 * Drawing routines
 * 
 */

#ifdef RCS
static char rcsid[] = "$Id: draw.c,v 1.1.1.1 2001-01-19 03:29:58 bradleyb Exp $";
#endif

#include <conf.h>
#include "error.h"

#include "fix.h"
#include "vecmat.h"
#include "gr.h"
#include "3d.h"
#include "globvars.h"
#include "texmap.h"
#include "clipper.h"

void (*tmap_drawer_ptr)(grs_bitmap *bm,int nv,g3s_point **vertlist) = draw_tmap;
void (*flat_drawer_ptr)(int nv,int *vertlist) = gr_upoly_tmap;
int (*line_drawer_ptr)(fix x0,fix y0,fix x1,fix y1) = gr_line;

//specifies 2d drawing routines to use instead of defaults.  Passing
//NULL for either or both restores defaults
void g3_set_special_render(void (*tmap_drawer)(),void (*flat_drawer)(),int (*line_drawer)(fix, fix, fix, fix))
{
	tmap_drawer_ptr = (tmap_drawer)?tmap_drawer:draw_tmap;
	flat_drawer_ptr = (flat_drawer)?flat_drawer:gr_upoly_tmap;
	line_drawer_ptr = (line_drawer)?line_drawer:gr_line;
}
#ifndef OGL
//deal with a clipped line
bool must_clip_line(g3s_point *p0,g3s_point *p1,ubyte codes_or)
{
	bool ret;

	if ((p0->p3_flags&PF_TEMP_POINT) || (p1->p3_flags&PF_TEMP_POINT))

		ret = 0;		//line has already been clipped, so give up

	else {

		clip_line(&p0,&p1,codes_or);

		ret = g3_draw_line(p0,p1);
	}

	//free temp points

	if (p0->p3_flags & PF_TEMP_POINT)
		free_temp_point(p0);

	if (p1->p3_flags & PF_TEMP_POINT)
		free_temp_point(p1);

	return ret;
}

//draws a line. takes two points.  returns true if drew
bool g3_draw_line(g3s_point *p0,g3s_point *p1)
{
	ubyte codes_or;

	if (p0->p3_codes & p1->p3_codes)
		return 0;

	codes_or = p0->p3_codes | p1->p3_codes;

	if (codes_or & CC_BEHIND)
		return must_clip_line(p0,p1,codes_or);

	if (!(p0->p3_flags&PF_PROJECTED))
		g3_project_point(p0);

	if (p0->p3_flags&PF_OVERFLOW)
		return must_clip_line(p0,p1,codes_or);


	if (!(p1->p3_flags&PF_PROJECTED))
		g3_project_point(p1);

	if (p1->p3_flags&PF_OVERFLOW)
		return must_clip_line(p0,p1,codes_or);

	return (bool) (*line_drawer_ptr)(p0->p3_sx,p0->p3_sy,p1->p3_sx,p1->p3_sy);
}
#endif

//returns true if a plane is facing the viewer. takes the unrotated surface 
//normal of the plane, and a point on it.  The normal need not be normalized
bool g3_check_normal_facing(vms_vector *v,vms_vector *norm)
{
	vms_vector tempv;

	vm_vec_sub(&tempv,&View_position,v);

	return (vm_vec_dot(&tempv,norm) > 0);
}

bool do_facing_check(vms_vector *norm,g3s_point **vertlist,vms_vector *p)
{
	if (norm) {		//have normal

		Assert(norm->x || norm->y || norm->z);

		return g3_check_normal_facing(p,norm);
	}
	else {	//normal not specified, so must compute

		vms_vector tempv;

		//get three points (rotated) and compute normal

		vm_vec_perp(&tempv,&vertlist[0]->p3_vec,&vertlist[1]->p3_vec,&vertlist[2]->p3_vec);

		return (vm_vec_dot(&tempv,&vertlist[1]->p3_vec) < 0);
	}
}

//like g3_draw_poly(), but checks to see if facing.  If surface normal is
//NULL, this routine must compute it, which will be slow.  It is better to 
//pre-compute the normal, and pass it to this function.  When the normal
//is passed, this function works like g3_check_normal_facing() plus
//g3_draw_poly().
//returns -1 if not facing, 1 if off screen, 0 if drew
bool g3_check_and_draw_poly(int nv,g3s_point **pointlist,vms_vector *norm,vms_vector *pnt)
{
	if (do_facing_check(norm,pointlist,pnt))
		return g3_draw_poly(nv,pointlist);
	else
		return 255;
}

bool g3_check_and_draw_tmap(int nv,g3s_point **pointlist,g3s_uvl *uvl_list,grs_bitmap *bm,vms_vector *norm,vms_vector *pnt)
{
	if (do_facing_check(norm,pointlist,pnt))
		return g3_draw_tmap(nv,pointlist,uvl_list,bm);
	else
		return 255;
}

//deal with face that must be clipped
bool must_clip_flat_face(int nv,g3s_codes cc)
{
	int i;
        bool ret=0;
	g3s_point **bufptr;

	bufptr = clip_polygon(Vbuf0,Vbuf1,&nv,&cc);

	if (nv>0 && !(cc.or&CC_BEHIND) && !cc.and) {

		for (i=0;i<nv;i++) {
			g3s_point *p = bufptr[i];
	
			if (!(p->p3_flags&PF_PROJECTED))
				g3_project_point(p);
	
			if (p->p3_flags&PF_OVERFLOW) {
				ret = 1;
				goto free_points;
			}

			Vertex_list[i*2]   = p->p3_sx;
			Vertex_list[i*2+1] = p->p3_sy;
		}
	
		(*flat_drawer_ptr)(nv,(int *)Vertex_list);
	}
	else 
		ret=1;

	//free temp points
free_points:
	;

	for (i=0;i<nv;i++)
		if (Vbuf1[i]->p3_flags & PF_TEMP_POINT)
			free_temp_point(Vbuf1[i]);

//	Assert(free_point_num==0);

	return ret;
}

#if (!(defined(D1XD3D) || defined(OGL)))
//draw a flat-shaded face.
//returns 1 if off screen, 0 if drew
bool g3_draw_poly(int nv,g3s_point **pointlist)
{
	int i;
	g3s_point **bufptr;
	g3s_codes cc;

	cc.or = 0; cc.and = 0xff;

	bufptr = Vbuf0;

	for (i=0;i<nv;i++) {

		bufptr[i] = pointlist[i];

		cc.and &= bufptr[i]->p3_codes;
		cc.or  |= bufptr[i]->p3_codes;
	}

	if (cc.and)
		return 1;	//all points off screen

	if (cc.or)
		return must_clip_flat_face(nv,cc);

	//now make list of 2d coords (& check for overflow)

	for (i=0;i<nv;i++) {
		g3s_point *p = bufptr[i];

		if (!(p->p3_flags&PF_PROJECTED))
			g3_project_point(p);

		if (p->p3_flags&PF_OVERFLOW)
			return must_clip_flat_face(nv,cc);

		Vertex_list[i*2]   = p->p3_sx;
		Vertex_list[i*2+1] = p->p3_sy;
	}

	(*flat_drawer_ptr)(nv,(int *)Vertex_list);

	return 0;	//say it drew
}

bool must_clip_tmap_face(int nv,g3s_codes cc,grs_bitmap *bm);

//draw a texture-mapped face.
//returns 1 if off screen, 0 if drew
bool g3_draw_tmap(int nv,g3s_point **pointlist,g3s_uvl *uvl_list,grs_bitmap *bm)
{
	int i;
	g3s_point **bufptr;
	g3s_codes cc;

	cc.or = 0; cc.and = 0xff;

	bufptr = Vbuf0;

	for (i=0;i<nv;i++) {
		g3s_point *p;

		p = bufptr[i] = pointlist[i];

		cc.and &= p->p3_codes;
		cc.or  |= p->p3_codes;

		p->p3_u = uvl_list[i].u;
		p->p3_v = uvl_list[i].v;
		p->p3_l = uvl_list[i].l;

		p->p3_flags |= PF_UVS + PF_LS;

	}

	if (cc.and)
		return 1;	//all points off screen

	if (cc.or)
		return must_clip_tmap_face(nv,cc,bm);

	//now make list of 2d coords (& check for overflow)

	for (i=0;i<nv;i++) {
		g3s_point *p = bufptr[i];

		if (!(p->p3_flags&PF_PROJECTED))
			g3_project_point(p);

		if (p->p3_flags&PF_OVERFLOW) {
			Int3();		//should not overflow after clip
			return 255;
		}
	}

	(*tmap_drawer_ptr)(bm,nv,bufptr);

	return 0;	//say it drew
}
#endif

bool must_clip_tmap_face(int nv,g3s_codes cc,grs_bitmap *bm)
{
	g3s_point **bufptr;
	int i;

	bufptr = clip_polygon(Vbuf0,Vbuf1,&nv,&cc);

	if (nv && !(cc.or&CC_BEHIND) && !cc.and) {

		for (i=0;i<nv;i++) {
			g3s_point *p = bufptr[i];

			if (!(p->p3_flags&PF_PROJECTED))
				g3_project_point(p);
	
			if (p->p3_flags&PF_OVERFLOW) {
				Int3();		//should not overflow after clip
				goto free_points;
			}
		}

		(*tmap_drawer_ptr)(bm,nv,bufptr);
	}

free_points:
	;

	for (i=0;i<nv;i++)
		if (bufptr[i]->p3_flags & PF_TEMP_POINT)
			free_temp_point(bufptr[i]);

//	Assert(free_point_num==0);
	
	return 0;

}

#ifndef __powerc
int checkmuldiv(fix *r,fix a,fix b,fix c);
#endif

#ifndef OGL
//draw a sortof sphere - i.e., the 2d radius is proportional to the 3d
//radius, but not to the distance from the eye
int g3_draw_sphere(g3s_point *pnt,fix rad)
{
	if (! (pnt->p3_codes & CC_BEHIND)) {

		if (! (pnt->p3_flags & PF_PROJECTED))
			g3_project_point(pnt);

		if (! (pnt->p3_codes & PF_OVERFLOW)) {
			fix r2,t;

			r2 = fixmul(rad,Matrix_scale.x);
#ifndef __powerc
			if (checkmuldiv(&t,r2,Canv_w2,pnt->p3_z))
				return gr_disk(pnt->p3_sx,pnt->p3_sy,t);
#else
			if (pnt->p3_z == 0)
				return 0;
			return gr_disk(pnt->p3_sx, pnt->p3_sy, fl2f(((f2fl(r2) * fCanv_w2) / f2fl(pnt->p3_z))));
#endif
		}
	}

	return 0;
}
#endif