/*
Copyright (C) 1996-1997 Id Software, Inc.

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  

See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

*/

#include <math.h>

#include "quakedef.h"
#include "r_local.h"
#include "d_local.h"	// FIXME: shouldn't need to include this

#define MAXLEFTCLIPEDGES		100

// !!! if these are changed, they must be changed in asm_draw.h too !!!
#define FULLY_CLIPPED_CACHED	0x80000000
#define FRAMECOUNT_MASK			0x7FFFFFFF

unsigned int	cacheoffset;

int				c_faceclip;					// number of faces clipped

zpointdesc_t	r_zpointdesc;

polydesc_t		r_polydesc;

clipplane_t	*entity_clipplanes;
clipplane_t	view_clipplanes[4];
clipplane_t	world_clipplanes[16];

medge_t			*r_pedge;

qboolean		r_leftclipped, r_rightclipped;
static qboolean	makeleftedge, makerightedge;
qboolean		r_nearzionly;

int		sintable[MAXWIDTH + CYCLE];
int		intsintable[MAXWIDTH + CYCLE];

mvertex_t	r_leftenter, r_leftexit;
mvertex_t	r_rightenter, r_rightexit;

typedef struct {
	float	u,v;
	int		ceilv;
} evert_t;

int				r_emitted;
float			r_nearzi;
float			r_u1, r_v1, r_lzi1;
int				r_ceilv1;

qboolean	r_lastvertvalid;


#if	!id386

/*
================
R_EmitEdge
================
*/
void R_EmitEdge (mvertex_t *pv0, mvertex_t *pv1) {
	edge_t *edge, *pcheck;
	int u_check, v, v2, ceilv0, side;
	float u, u_step, *world, scale, lzi0, u0, v0;
	vec3_t local, transformed;

	if (r_lastvertvalid) {
		u0 = r_u1;
		v0 = r_v1;
		lzi0 = r_lzi1;
		ceilv0 = r_ceilv1;
	} else {
		world = &pv0->position[0];
	
		// transform and project
		VectorSubtract (world, modelorg, local);
		TransformVector (local, transformed);
	
		if (transformed[2] < NEAR_CLIP)
			transformed[2] = NEAR_CLIP;
	
		lzi0 = 1.0 / transformed[2];
	
		// FIXME: build x/yscale into transform?
		scale = xscale * lzi0;
		u0 = (xcenter + scale * transformed[0]);
		u0 = bound(r_refdef.fvrectx_adj, u0, r_refdef.fvrectright_adj);
	
		scale = yscale * lzi0;
		v0 = (ycenter - scale * transformed[1]);
		v0 = bound(r_refdef.fvrecty_adj, v0, r_refdef.fvrectbottom_adj);
	
		ceilv0 = (int) ceil(v0);
	}

	world = &pv1->position[0];

	// transform and project
	VectorSubtract (world, modelorg, local);
	TransformVector (local, transformed);

	if (transformed[2] < NEAR_CLIP)
		transformed[2] = NEAR_CLIP;

	r_lzi1 = 1.0 / transformed[2];

	scale = xscale * r_lzi1;
	r_u1 = (xcenter + scale * transformed[0]);
	r_u1 = bound(r_refdef.fvrectx_adj, r_u1, r_refdef.fvrectright_adj);

	scale = yscale * r_lzi1;
	r_v1 = (ycenter - scale * transformed[1]);
	r_v1 = bound(r_refdef.fvrecty_adj, r_v1, r_refdef.fvrectbottom_adj);

	if (r_lzi1 > lzi0)
		lzi0 = r_lzi1;

	if (lzi0 > r_nearzi)	// for mipmap finding
		r_nearzi = lzi0;

	// for right edges, all we want is the effect on 1/z
	if (r_nearzionly)
		return;

	r_emitted = 1;

	r_ceilv1 = (int) ceil(r_v1);


	// create the edge
	if (ceilv0 == r_ceilv1) {
		// we cache unclipped horizontal edges as fully clipped
		if (cacheoffset != 0x7FFFFFFF)
			cacheoffset = FULLY_CLIPPED_CACHED |(r_framecount & FRAMECOUNT_MASK);
		return;		// horizontal edge
	}

	side = ceilv0 > r_ceilv1;

	edge = edge_p++;

	edge->owner = r_pedge;

	edge->nearzi = lzi0;

	if (side == 0) {
		// trailing edge (go from p1 to p2)
		v = ceilv0;
		v2 = r_ceilv1 - 1;

		edge->surfs[0] = surface_p - surfaces;
		edge->surfs[1] = 0;

		u_step = ((r_u1 - u0) / (r_v1 - v0));
		u = u0 + ((float)v - v0) * u_step;
	} else {
		// leading edge (go from p2 to p1)
		v2 = ceilv0 - 1;
		v = r_ceilv1;

		edge->surfs[0] = 0;
		edge->surfs[1] = surface_p - surfaces;

		u_step = ((u0 - r_u1) / (v0 - r_v1));
		u = r_u1 + ((float)v - r_v1) * u_step;
	}

	edge->u_step = u_step*0x100000;
	edge->u = u*0x100000 + 0xFFFFF;

	// we need to do this to avoid stepping off the edges if a very nearly horizontal edge is less
	// than epsilon above a scan, and numeric error causes it to incorrectly extend to the scan,
	// and the extension of the line goes off the edge of the screen
	// FIXME: is this actually needed?
	if (edge->u < r_refdef.vrect_x_adj_shift20)
		edge->u = r_refdef.vrect_x_adj_shift20;
	if (edge->u > r_refdef.vrectright_adj_shift20)
		edge->u = r_refdef.vrectright_adj_shift20;

	// sort the edge in normally
	u_check = edge->u;
	if (edge->surfs[0])
		u_check++;	// sort trailers after leaders

	if (!newedges[v] || newedges[v]->u >= u_check) {
		edge->next = newedges[v];
		newedges[v] = edge;
	} else {
		pcheck = newedges[v];
		while (pcheck->next && pcheck->next->u < u_check)
			pcheck = pcheck->next;
		edge->next = pcheck->next;
		pcheck->next = edge;
	}

	edge->nextremove = removeedges[v2];
	removeedges[v2] = edge;
}

void R_ClipEdge (mvertex_t *pv0, mvertex_t *pv1, clipplane_t *clip) {
	float d0, d1, f;
	mvertex_t clipvert;

	if (clip) {
		do {
			d0 = DotProduct (pv0->position, clip->normal) - clip->dist;
			d1 = DotProduct (pv1->position, clip->normal) - clip->dist;

			if (d0 >= 0) {
				// point 0 is unclipped
				if (d1 >= 0) {
					// both points are unclipped
					continue;
				}

				// only point 1 is clipped

				// we don't cache clipped edges
				cacheoffset = 0x7FFFFFFF;

				f = d0 / (d0 - d1);
				VectorInterpolate(pv0->position, f, pv1->position, clipvert.position);

				if (clip->leftedge) {
					r_leftclipped = true;
					r_leftexit = clipvert;
				} else if (clip->rightedge) {
					r_rightclipped = true;
					r_rightexit = clipvert;
				}

				R_ClipEdge (pv0, &clipvert, clip->next);
				return;
			} else {
				// point 0 is clipped
				if (d1 < 0) {
					// both points are clipped
					// we do cache fully clipped edges
					if (!r_leftclipped)
						cacheoffset = FULLY_CLIPPED_CACHED | (r_framecount & FRAMECOUNT_MASK);
					return;
				}

				// only point 0 is clipped
				r_lastvertvalid = false;

				// we don't cache partially clipped edges
				cacheoffset = 0x7FFFFFFF;

				f = d0 / (d0 - d1);
				VectorInterpolate(pv0->position, f, pv1->position, clipvert.position);

				if (clip->leftedge) {
					r_leftclipped = true;
					r_leftenter = clipvert;
				} else if (clip->rightedge) {
					r_rightclipped = true;
					r_rightenter = clipvert;
				}

				R_ClipEdge (&clipvert, pv1, clip->next);
				return;
			}
		} while ((clip = clip->next) != NULL);
	}

	// add the edge
	R_EmitEdge (pv0, pv1);
}

#endif	// !id386

void R_EmitCachedEdge (void) {
	edge_t *pedge_t;

	pedge_t = (edge_t *)((unsigned long)r_edges + r_pedge->cachededgeoffset);

	if (!pedge_t->surfs[0])
		pedge_t->surfs[0] = surface_p - surfaces;
	else
		pedge_t->surfs[1] = surface_p - surfaces;

	if (pedge_t->nearzi > r_nearzi)	// for mipmap finding
		r_nearzi = pedge_t->nearzi;

	r_emitted = 1;
}

void R_RenderFace (msurface_t *fa, int clipflags) {
	int i, lindex;
	unsigned mask;
	mplane_t *pplane;
	float distinv;
	vec3_t p_normal;
	medge_t *pedges, tedge;
	clipplane_t *pclip;

	// skip out if no more surfs
	if (surface_p >= surf_max) {
		r_outofsurfaces++;
		return;
	}

	// ditto if not enough edges left, or switch to auxedges if possible
	if ((edge_p + fa->numedges + 4) >= edge_max) {
		r_outofedges += fa->numedges;
		return;
	}

	c_faceclip++;

	// set up clip planes
	pclip = NULL;

	for (i = 3, mask = 0x08; i >= 0; i--, mask >>= 1) {
		if (clipflags & mask) {
			view_clipplanes[i].next = pclip;
			pclip = &view_clipplanes[i];
		}
	}

	// push the edges through
	r_emitted = 0;
	r_nearzi = 0;
	r_nearzionly = false;
	makeleftedge = makerightedge = false;
	pedges = currententity->model->edges;
	r_lastvertvalid = false;

	for (i = 0; i < fa->numedges; i++) {
		lindex = currententity->model->surfedges[fa->firstedge + i];

		if (lindex > 0) {
			r_pedge = &pedges[lindex];

			// if the edge is cached, we can just reuse the edge
			if (!insubmodel) {
				if (r_pedge->cachededgeoffset & FULLY_CLIPPED_CACHED) {
					if ((r_pedge->cachededgeoffset & FRAMECOUNT_MASK) == r_framecount) {
						r_lastvertvalid = false;
						continue;
					}
				} else {
					if ((((unsigned long)edge_p - (unsigned long)r_edges) > r_pedge->cachededgeoffset) &&
						(((edge_t *)((unsigned long) r_edges + r_pedge->cachededgeoffset))->owner == r_pedge))
					{
						R_EmitCachedEdge ();
						r_lastvertvalid = false;
						continue;
					}
				}
			}

			// assume it's cacheable
			cacheoffset = (byte *)edge_p - (byte *)r_edges;
			r_leftclipped = r_rightclipped = false;
			R_ClipEdge (&r_pcurrentvertbase[r_pedge->v[0]], &r_pcurrentvertbase[r_pedge->v[1]], pclip);
			r_pedge->cachededgeoffset = cacheoffset;

			if (r_leftclipped)
				makeleftedge = true;
			if (r_rightclipped)
				makerightedge = true;
			r_lastvertvalid = true;
		} else {
			lindex = -lindex;
			r_pedge = &pedges[lindex];
			// if the edge is cached, we can just reuse the edge
			if (!insubmodel) {
				if (r_pedge->cachededgeoffset & FULLY_CLIPPED_CACHED) {
					if ((r_pedge->cachededgeoffset & FRAMECOUNT_MASK) == r_framecount) {
						r_lastvertvalid = false;
						continue;
					}
				} else {
					// it's cached if the cached edge is valid and is owned by this medge_t
					if ((((unsigned long)edge_p - (unsigned long)r_edges) > r_pedge->cachededgeoffset) &&
						(((edge_t *)((unsigned long)r_edges + r_pedge->cachededgeoffset))->owner == r_pedge))
					{
						R_EmitCachedEdge ();
						r_lastvertvalid = false;
						continue;
					}
				}
			}

			// assume it's cacheable
			cacheoffset = (byte *)edge_p - (byte *)r_edges;
			r_leftclipped = r_rightclipped = false;
			R_ClipEdge (&r_pcurrentvertbase[r_pedge->v[1]], &r_pcurrentvertbase[r_pedge->v[0]], pclip);
			r_pedge->cachededgeoffset = cacheoffset;

			if (r_leftclipped)
				makeleftedge = true;
			if (r_rightclipped)
				makerightedge = true;
			r_lastvertvalid = true;
		}
	}

	// if there was a clip off the left edge, add that edge too
	// FIXME: faster to do in screen space?
	// FIXME: share clipped edges?
	if (makeleftedge) {
		r_pedge = &tedge;
		r_lastvertvalid = false;
		R_ClipEdge (&r_leftexit, &r_leftenter, pclip->next);
	}

	// if there was a clip off the right edge, get the right r_nearzi
	if (makerightedge) {
		r_pedge = &tedge;
		r_lastvertvalid = false;
		r_nearzionly = true;
		R_ClipEdge (&r_rightexit, &r_rightenter, view_clipplanes[1].next);
	}

	// if no edges made it out, return without posting the surface
	if (!r_emitted)
		return;

	r_polycount++;

	surface_p->data = (void *)fa;
	surface_p->nearzi = r_nearzi;
	surface_p->flags = fa->flags;
	surface_p->insubmodel = insubmodel;
	surface_p->spanstate = 0;
	surface_p->entity = currententity;
	surface_p->key = r_currentkey++;
	surface_p->spans = NULL;

	pplane = fa->plane;
	// FIXME: cache this?
	TransformVector (pplane->normal, p_normal);
	// FIXME: cache this?
	distinv = 1.0 / (-PlaneDiff(modelorg, pplane));

	surface_p->d_zistepu = p_normal[0] * xscaleinv * distinv;
	surface_p->d_zistepv = -p_normal[1] * yscaleinv * distinv;
	surface_p->d_ziorigin = p_normal[2] * distinv - xcenter * surface_p->d_zistepu - ycenter * surface_p->d_zistepv;

	surface_p++;
}

void R_RenderBmodelFace (bedge_t *pedges, msurface_t *psurf) {
	int i;
	unsigned mask;
	mplane_t *pplane;
	float distinv;
	vec3_t p_normal;
	medge_t tedge;
	clipplane_t	*pclip;

	// skip out if no more surfs
	if (surface_p >= surf_max) {
		r_outofsurfaces++;
		return;
	}

	// ditto if not enough edges left, or switch to auxedges if possible
	if ((edge_p + psurf->numedges + 4) >= edge_max) {
		r_outofedges += psurf->numedges;
		return;
	}

	c_faceclip++;

	// this is a dummy to give the caching mechanism someplace to write to
	r_pedge = &tedge;

	// set up clip planes
	pclip = NULL;

	for (i = 3, mask = 0x08 ; i >= 0 ; i--, mask >>= 1) {
		if (r_clipflags & mask) {
			view_clipplanes[i].next = pclip;
			pclip = &view_clipplanes[i];
		}
	}

	// push the edges through
	r_emitted = 0;
	r_nearzi = 0;
	r_nearzionly = false;
	makeleftedge = makerightedge = false;
	// FIXME: keep clipped bmodel edges in clockwise order so last vertex caching can be used?
	r_lastvertvalid = false;

	for ( ; pedges ; pedges = pedges->pnext) {
		r_leftclipped = r_rightclipped = false;
		R_ClipEdge (pedges->v[0], pedges->v[1], pclip);

		if (r_leftclipped)
			makeleftedge = true;
		if (r_rightclipped)
			makerightedge = true;
	}

	// if there was a clip off the left edge, add that edge too
	// FIXME: faster to do in screen space?
	// FIXME: share clipped edges?
	if (makeleftedge) {
		r_pedge = &tedge;
		R_ClipEdge (&r_leftexit, &r_leftenter, pclip->next);
	}

	// if there was a clip off the right edge, get the right r_nearzi
	if (makerightedge) {
		r_pedge = &tedge;
		r_nearzionly = true;
		R_ClipEdge (&r_rightexit, &r_rightenter, view_clipplanes[1].next);
	}

	// if no edges made it out, return without posting the surface
	if (!r_emitted)
		return;

	r_polycount++;

	surface_p->data = (void *)psurf;
	surface_p->nearzi = r_nearzi;
	surface_p->flags = psurf->flags;
	surface_p->insubmodel = true;
	surface_p->spanstate = 0;
	surface_p->entity = currententity;
	surface_p->key = r_currentbkey;
	surface_p->spans = NULL;

	pplane = psurf->plane;
	// FIXME: cache this?
	TransformVector (pplane->normal, p_normal);
	// FIXME: cache this?
	distinv = 1.0 / (-PlaneDiff(modelorg, pplane));

	surface_p->d_zistepu = p_normal[0] * xscaleinv * distinv;
	surface_p->d_zistepv = -p_normal[1] * yscaleinv * distinv;
	surface_p->d_ziorigin = p_normal[2] * distinv - xcenter * surface_p->d_zistepu - ycenter * surface_p->d_zistepv;

	surface_p++;
}
