/*
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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

*/

// r_draw.c

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

#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

int c_faceclip;			// number of faces clipped
unsigned int cacheoffset;
clipplane_t view_clipplanes[4];

medge_t *r_pedge;

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

int sintable[TURB_TABLE_SIZE];
int intsintable[TURB_TABLE_SIZE];

mvertex_t r_leftenter, r_leftexit;
mvertex_t r_rightenter, r_rightexit;

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

qboolean r_lastvertvalid;


#ifndef USE_X86_ASM

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

    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]);
	if (u0 < r_refdef.fvrectx_adj)
	    u0 = r_refdef.fvrectx_adj;
	if (u0 > r_refdef.fvrectright_adj)
	    u0 = r_refdef.fvrectright_adj;

	scale = yscale * lzi0;
	v0 = (ycenter - scale * transformed[1]);
	if (v0 < r_refdef.fvrecty_adj)
	    v0 = r_refdef.fvrecty_adj;
	if (v0 > r_refdef.fvrectbottom_adj)
	    v0 = r_refdef.fvrectbottom_adj;

	ceilv0 = (int)ceilf(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]);
    if (r_u1 < r_refdef.fvrectx_adj)
	r_u1 = r_refdef.fvrectx_adj;
    if (r_u1 > r_refdef.fvrectright_adj)
	r_u1 = r_refdef.fvrectright_adj;

    scale = yscale * r_lzi1;
    r_v1 = (ycenter - scale * transformed[1]);
    if (r_v1 < r_refdef.fvrecty_adj)
	r_v1 = r_refdef.fvrecty_adj;
    if (r_v1 > r_refdef.fvrectbottom_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)ceilf(r_v1);

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


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

    if (clip) {
	do {
	    plane = &clip->plane;
	    d0 = DotProduct(pv0->position, plane->normal) - plane->dist;
	    d1 = DotProduct(pv1->position, plane->normal) - plane->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);
		clipvert.position[0] = pv0->position[0] +
		    f * (pv1->position[0] - pv0->position[0]);
		clipvert.position[1] = pv0->position[1] +
		    f * (pv1->position[1] - pv0->position[1]);
		clipvert.position[2] = pv0->position[2] +
		    f * (pv1->position[2] - pv0->position[2]);

		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);
		clipvert.position[0] = pv0->position[0] +
		    f * (pv1->position[0] - pv0->position[0]);
		clipvert.position[1] = pv0->position[1] +
		    f * (pv1->position[1] - pv0->position[1]);
		clipvert.position[2] = pv0->position[2] +
		    f * (pv1->position[2] - pv0->position[2]);

		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 /* USE_X86_ASM */


/*
================
R_EmitCachedEdge
================
*/
static qboolean
R_EmitCachedEdge(void)
{
    edge_t *edge;

    /* If fully clipped, no action necessary */
    if (r_pedge->cachededgeoffset & FULLY_CLIPPED_CACHED)
	return (r_pedge->cachededgeoffset & FRAMECOUNT_MASK) == r_framecount;

    /* It's cached if the cached edge is valid and is owned by this medge_t */
    if ((byte *)edge_p - (byte *)r_edges <= r_pedge->cachededgeoffset)
	return false;
    edge = (edge_t *)((byte *)r_edges + r_pedge->cachededgeoffset);
    if (edge->owner != r_pedge)
	return false;

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

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

    r_emitted = 1;

    return true;
}


/*
================
R_RenderFace
================
*/
void
R_RenderFace(const entity_t *entity, msurface_t *surf, int clipflags)
{
    const brushmodel_t *brushmodel = BrushModel(entity->model);
    const qboolean insubmodel = entity->model != r_worldentity.model;
    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_surfaces_overflow = true;
	return;
    }
// ditto if not enough edges left, or switch to auxedges if possible
    if ((edge_p + surf->numedges + 4) >= edge_max) {
	r_edges_overflow = true;
	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 = brushmodel->edges;
    r_lastvertvalid = false;

    for (i = 0; i < surf->numedges; i++) {
	lindex = brushmodel->surfedges[surf->firstedge + i];

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

	    // if the edge is cached, we can just reuse the edge
	    if (!insubmodel && R_EmitCachedEdge()) {
		r_lastvertvalid = false;
		continue;
	    }

	    // assume it's cacheable
	    cacheoffset = (byte *)edge_p - (byte *)r_edges;
	    r_leftclipped = r_rightclipped = false;
	    R_ClipEdge(&brushmodel->vertexes[r_pedge->v[0]],
		       &brushmodel->vertexes[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 && R_EmitCachedEdge()) {
		r_lastvertvalid = false;
		continue;
	    }

	    // assume it's cacheable
	    cacheoffset = (byte *)edge_p - (byte *)r_edges;
	    r_leftclipped = r_rightclipped = false;
	    R_ClipEdge(&brushmodel->vertexes[r_pedge->v[1]],
		       &brushmodel->vertexes[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 *)surf;
    surface_p->nearzi = r_nearzi;
    surface_p->flags = surf->flags;
    surface_p->insubmodel = insubmodel;
    surface_p->spanstate = 0;
    surface_p->entity = entity;
    surface_p->key = r_currentkey++;
    surface_p->spans = NULL;

    /* Flag alpha surfs */
    float alpha = R_GetSurfAlpha(surf->flags);
    if (entity->alpha != ENTALPHA_DEFAULT && entity->alpha != ENTALPHA_ONE) {
        alpha *= ENTALPHA_DECODE(entity->alpha);
        surface_p->flags |= SURF_DRAWENTALPHA;
    } else {
        surface_p->flags &= ~SURF_DRAWENTALPHA;
    }
    surface_p->alphatable = Alpha_Transtable(alpha);

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

    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++;
}


/*
================
R_RenderBmodelFace
================
*/
void
R_RenderBmodelFace(const entity_t *entity, bedge_t *pedges, msurface_t *psurf)
{
    int i;
    float alpha;
    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_surfaces_overflow = true;
	return;
    }
// ditto if not enough edges left, or switch to auxedges if possible
    if ((edge_p + psurf->numedges + 4) >= edge_max) {
	r_edges_overflow = true;
	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 (psurf->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 = entity;
    surface_p->key = r_currentbkey;
    surface_p->spans = NULL;

    /* Flag alpha surfs */
    alpha = R_GetSurfAlpha(psurf->flags);
    if (entity->alpha != ENTALPHA_DEFAULT && entity->alpha != ENTALPHA_ONE) {
        alpha *= ENTALPHA_DECODE(entity->alpha);
        surface_p->flags |= SURF_DRAWENTALPHA;
    } else {
        surface_p->flags &= ~SURF_DRAWENTALPHA;
    }
    surface_p->alphatable = Alpha_Transtable(alpha);

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

    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++;
}
