/*
 * 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.
 *
 */
// r_draw.c

#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) {
    int           u_check, v, v2, ceilv0, side;
    float         u, u_step, scale, lzi0, u0, v0, *world;
    vec3_t        local, transformed;
    edge_t       *edge, *pcheck;

    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) 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]);
    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) 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;
}

/*
 * R_ClipEdge
 */
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);
                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                                 // !id386

/*
 * R_EmitCachedEdge
 */
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;
}

/*
 * R_RenderFace
 */
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++;
}

/*
 * R_RenderBmodelFace
 */
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++;
}
