faces.cpp

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/*
Copyright (C) 1997-2001 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 "bsp.h"

#define INTEGRAL_EPSILON    0.01
#define POINT_EPSILON       0.0625
#define OFF_EPSILON         0.5

static int c_merge, c_subdivide, c_totalverts, c_uniqueverts, c_degenerate, c_tjunctions, c_faceoverflows, c_facecollapse, c_badstartverts, c_faces;

#define MAX_SUPERVERTS  512
static int superverts[MAX_SUPERVERTS];
static int numsuperverts;

static const face_t* edgefaces[MAX_MAP_EDGES][2];
int firstmodeledge = 1;

static vec3_t edge_dir;
static vec3_t edge_start;

static int num_edge_verts;
static int edge_verts[MAX_MAP_VERTS];

#define HASH_SIZE   64

static int vertexchain[MAX_MAP_VERTS];      /* the next vertex in a hash chain */
static int hashverts[HASH_SIZE * HASH_SIZE];    /* a vertex number, or 0 for no verts */

static unsigned HashVec (const vec3_t vec)
{
    const int x = (4096 + (int)(vec[0] + 0.5)) >> 7;
    const int y = (4096 + (int)(vec[1] + 0.5)) >> 7;

    if (x < 0 || x >= HASH_SIZE || y < 0 || y >= HASH_SIZE)
        Sys_Error("HashVec: point outside valid range");

    return y * HASH_SIZE + x;
}

static int GetVertexnum (const vec3_t in)
{
    vec3_t vert;

    c_totalverts++;

    for (int i = 0; i < 3; i++) {
        if (fabs(in[i] - Q_rint(in[i])) < INTEGRAL_EPSILON)
            vert[i] = Q_rint(in[i]);
        else
            vert[i] = in[i];
    }

    int h = HashVec(vert);

    for (int vnum = hashverts[h]; vnum; vnum = vertexchain[vnum]) {
        const float* p = curTile->vertexes[vnum].point;
        if (fabs(p[0] - vert[0]) < POINT_EPSILON
         && fabs(p[1] - vert[1]) < POINT_EPSILON
         && fabs(p[2] - vert[2]) < POINT_EPSILON)
            return vnum;
    }

    /* emit a vertex */
    if (curTile->numvertexes == MAX_MAP_VERTS)
        Sys_Error("numvertexes == MAX_MAP_VERTS");

    curTile->vertexes[curTile->numvertexes].point[0] = vert[0];
    curTile->vertexes[curTile->numvertexes].point[1] = vert[1];
    curTile->vertexes[curTile->numvertexes].point[2] = vert[2];

    vertexchain[curTile->numvertexes] = hashverts[h];
    hashverts[h] = curTile->numvertexes;

    c_uniqueverts++;

    curTile->numvertexes++;
    curTile->numnormals++;

    return curTile->numvertexes - 1;
}

static face_t* AllocFace (void)
{
    c_faces++;

    return Mem_AllocType(face_t);
}

static face_t* NewFaceFromFace (const face_t* f)
{
    face_t* newf;

    newf = AllocFace();
    *newf = *f;
    newf->merged = nullptr;
    newf->split[0] = newf->split[1] = nullptr;
    newf->w = nullptr;
    return newf;
}

void FreeFace (face_t* f)
{
    if (f->w)
        FreeWinding(f->w);
    Mem_Free(f);
    c_faces--;
}

static void FaceFromSuperverts (node_t* node, face_t* f, int base)
{
    int i, remaining;

    remaining = numsuperverts;
    /* must split into two faces, because of vertex overload */
    while (remaining > MAXEDGES) {
        c_faceoverflows++;

        face_t* newf = f->split[0] = NewFaceFromFace(f);
        newf->next = node->faces;
        node->faces = newf;

        newf->numpoints = MAXEDGES;
        for (i = 0; i < MAXEDGES; i++)
            newf->vertexnums[i] = superverts[(i + base) % numsuperverts];

        f->split[1] = NewFaceFromFace(f);
        f = f->split[1];
        f->next = node->faces;
        node->faces = f;

        remaining -= (MAXEDGES - 2);
        base = (base + MAXEDGES - 1) % numsuperverts;
    }

    /* copy the vertexes back to the face */
    f->numpoints = remaining;
    for (i = 0; i < remaining; i++)
        f->vertexnums[i] = superverts[(i + base) % numsuperverts];
}

static void EmitFaceVertexes (node_t* node, face_t* f)
{
    if (f->merged || f->split[0] || f->split[1])
        return;

    winding_t* w = f->w;
    for (int i = 0; i < w->numpoints; i++) {
        /* make every point unique */
        if (config.noweld) {
            if (curTile->numvertexes == MAX_MAP_VERTS)
                Sys_Error("MAX_MAP_VERTS (%i)", curTile->numvertexes);
            superverts[i] = curTile->numvertexes;
            VectorCopy(w->p[i], curTile->vertexes[curTile->numvertexes].point);
            curTile->numvertexes++;
            curTile->numnormals++;
            c_uniqueverts++;
            c_totalverts++;
        } else
            superverts[i] = GetVertexnum(w->p[i]);
    }
    numsuperverts = w->numpoints;

    /* this may fragment the face if > MAXEDGES */
    FaceFromSuperverts(node, f, 0);
}

static void EmitVertexes_r (node_t* node)
{
    if (node->planenum == PLANENUM_LEAF)
        return;

    for (face_t* f = node->faces; f; f = f->next)
        EmitFaceVertexes(node, f);

    for (int i = 0; i < 2; i++)
        EmitVertexes_r(node->children[i]);
}


static void FindEdgeVerts (const vec3_t v1, const vec3_t v2)
{
    int x1, x2, y1, y2, t;
    int x, y, vnum;

    x1 = (MAX_WORLD_WIDTH + (int)(v1[0] + 0.5)) >> 7;
    y1 = (MAX_WORLD_WIDTH + (int)(v1[1] + 0.5)) >> 7;
    x2 = (MAX_WORLD_WIDTH + (int)(v2[0] + 0.5)) >> 7;
    y2 = (MAX_WORLD_WIDTH + (int)(v2[1] + 0.5)) >> 7;

    if (x1 > x2) {
        t = x1;
        x1 = x2;
        x2 = t;
    }
    if (y1 > y2) {
        t = y1;
        y1 = y2;
        y2 = t;
    }
    num_edge_verts = 0;
    for (x = x1; x <= x2; x++)
        for (y = y1; y <= y2; y++)
            for (vnum = hashverts[y * HASH_SIZE + x]; vnum; vnum = vertexchain[vnum])
                edge_verts[num_edge_verts++] = vnum;
}

static void TestEdge (vec_t start, vec_t end, int p1, int p2, int startvert)
{
    int k;
    vec_t dist, error;
    vec3_t  delta, exact, off, p;

    if (p1 == p2) {
        c_degenerate++;
        return;     /* degenerate edge */
    }

    for (k = startvert; k < num_edge_verts; k++) {
        const int j = edge_verts[k];
        if (j == p1 || j == p2)
            continue;

        VectorCopy(curTile->vertexes[j].point, p);

        VectorSubtract(p, edge_start, delta);
        dist = DotProduct(delta, edge_dir);
        if (dist <= start || dist >= end)
            continue;       /* off an end */
        VectorMA(edge_start, dist, edge_dir, exact);
        VectorSubtract(p, exact, off);
        error = VectorLength(off);

        if (fabs(error) > OFF_EPSILON)
            continue;       /* not on the edge */

        /* break the edge */
        c_tjunctions++;
        TestEdge(start, dist, p1, j, k + 1);
        TestEdge(dist, end, j, p2, k + 1);
        return;
    }

    /* the edge p1 to p2 is now free of tjunctions */
    if (numsuperverts >= MAX_SUPERVERTS)
        Sys_Error("MAX_SUPERVERTS (%i)", numsuperverts);
    superverts[numsuperverts] = p1;
    numsuperverts++;
}

static void FixFaceEdges (node_t* node, face_t* f)
{
    int i, base;
    vec3_t e2;
    int count[MAX_SUPERVERTS], start[MAX_SUPERVERTS];

    if (f->merged || f->split[0] || f->split[1])
        return;

    numsuperverts = 0;

    for (i = 0; i < f->numpoints; i++) {
        const int p1 = f->vertexnums[i];
        const int p2 = f->vertexnums[(i + 1) % f->numpoints];

        VectorCopy(curTile->vertexes[p1].point, edge_start);
        VectorCopy(curTile->vertexes[p2].point, e2);

        FindEdgeVerts(edge_start, e2);

        VectorSubtract(e2, edge_start, edge_dir);
        vec_t len = VectorNormalize(edge_dir);

        start[i] = numsuperverts;
        TestEdge(0, len, p1, p2, 0);

        count[i] = numsuperverts - start[i];
    }

    /* entire face collapsed */
    if (numsuperverts < 3) {
        f->numpoints = 0;
        c_facecollapse++;
        return;
    }

    /* we want to pick a vertex that doesn't have tjunctions
     * on either side, which can cause artifacts on trifans,
     * especially underwater */
    for (i = 0; i < f->numpoints; i++) {
        if (count[i] == 1 && count[(i + f->numpoints - 1) % f->numpoints] == 1)
            break;
    }
    if (i == f->numpoints) {
        c_badstartverts++;
        base = 0;
    } else {
        /* rotate the vertex order */
        base = start[i];
    }

    /* this may fragment the face if > MAXEDGES */
    FaceFromSuperverts(node, f, base);
}

static void FixEdges_r (node_t* node)
{
    if (node->planenum == PLANENUM_LEAF)
        return;

    for (face_t* f = node->faces; f; f = f->next)
        FixFaceEdges(node, f);

    for (int i = 0; i < 2; i++)
        FixEdges_r(node->children[i]);
}

void FixTjuncs (node_t* headnode)
{
    /* snap and merge all vertexes */
    Verb_Printf(VERB_EXTRA, "---- snap verts ----\n");
    OBJZERO(hashverts);
    c_totalverts = 0;
    c_uniqueverts = 0;
    c_faceoverflows = 0;
    EmitVertexes_r(headnode);
    Verb_Printf(VERB_EXTRA, "%i unique from %i\n", c_uniqueverts, c_totalverts);

    /* break edges on tjunctions */
    Verb_Printf(VERB_EXTRA, "---- tjunc ----\n");
    c_degenerate = 0;
    c_facecollapse = 0;
    c_tjunctions = 0;
    if (!config.notjunc)
        FixEdges_r(headnode);
    Verb_Printf(VERB_EXTRA, "%5i edges degenerated\n", c_degenerate);
    Verb_Printf(VERB_EXTRA, "%5i faces degenerated\n", c_facecollapse);
    Verb_Printf(VERB_EXTRA, "%5i edges added by tjunctions\n", c_tjunctions);
    Verb_Printf(VERB_EXTRA, "%5i faces added by tjunctions\n", c_faceoverflows);
    Verb_Printf(VERB_EXTRA, "%5i bad start verts\n", c_badstartverts);
}

int GetEdge (int v1, int v2, const face_t* f)
{
    dBspEdge_t* edge;

    if (!config.noshare) {
        int i;
        for (i = firstmodeledge; i < curTile->numedges; i++) {
            edge = &curTile->edges[i];
            if (v1 == edge->v[1] && v2 == edge->v[0]
                && edgefaces[i][0]->contentFlags == f->contentFlags) {
                if (edgefaces[i][1])
                    continue;
                edgefaces[i][1] = f;
                return -i;
            }
        }
    }

    /* emit an edge */
    if (curTile->numedges >= MAX_MAP_EDGES)
        Sys_Error("numedges >= MAX_MAP_EDGES (%i)", curTile->numedges);
    edge = &curTile->edges[curTile->numedges];
    edge->v[0] = v1;
    edge->v[1] = v2;
    edgefaces[curTile->numedges][0] = f;
    curTile->numedges++;

    return curTile->numedges - 1;
}

/*
===========================================================================
FACE MERGING
===========================================================================
*/

#define CONTINUOUS_EPSILON 0.001

static winding_t* TryMergeWinding (winding_t* f1, winding_t* f2, const vec3_t planenormal)
{
    vec_t* p1, *p2, *back;
    winding_t* newf;
    int i, j, k, l;
    vec3_t normal, delta;
    vec_t dot;
    bool keep1, keep2;

    p1 = p2 = nullptr;
    j = 0;

    /* find a common edge */
    for (i = 0; i < f1->numpoints; i++) {
        p1 = f1->p[i];
        p2 = f1->p[(i + 1) % f1->numpoints];
        for (j = 0; j < f2->numpoints; j++) {
            const vec_t* p3 = f2->p[j];
            const vec_t* p4 = f2->p[(j + 1) % f2->numpoints];
            for (k = 0; k < 3; k++) {
                if (fabs(p1[k] - p4[k]) > EQUAL_EPSILON)
                    break;
                if (fabs(p2[k] - p3[k]) > EQUAL_EPSILON)
                    break;
            }
            if (k == 3)
                break;
        }
        if (j < f2->numpoints)
            break;
    }

    /* no matching edges */
    if (i == f1->numpoints)
        return nullptr;

    /* check slope of connected lines */
    /* if the slopes are colinear, the point can be removed */
    back = f1->p[(i + f1->numpoints - 1) % f1->numpoints];
    VectorSubtract(p1, back, delta);
    CrossProduct(planenormal, delta, normal);
    VectorNormalize(normal);

    back = f2->p[(j + 2) % f2->numpoints];
    VectorSubtract(back, p1, delta);
    dot = DotProduct(delta, normal);
    /* not a convex polygon */
    if (dot > CONTINUOUS_EPSILON)
        return nullptr;
    keep1 = (bool)(dot < -CONTINUOUS_EPSILON);

    back = f1->p[(i + 2) % f1->numpoints];
    VectorSubtract(back, p2, delta);
    CrossProduct(planenormal, delta, normal);
    VectorNormalize(normal);

    back = f2->p[(j + f2->numpoints - 1) % f2->numpoints];
    VectorSubtract(back, p2, delta);
    dot = DotProduct(delta, normal);
    /* not a convex polygon */
    if (dot > CONTINUOUS_EPSILON)
        return nullptr;
    keep2 = (bool)(dot < -CONTINUOUS_EPSILON);

    /* build the new polygon */
    newf = AllocWinding(f1->numpoints + f2->numpoints);

    /* copy first polygon */
    for (k = (i + 1) % f1->numpoints; k != i; k = (k + 1) % f1->numpoints) {
        if (k == (i + 1) % f1->numpoints && !keep2)
            continue;

        VectorCopy(f1->p[k], newf->p[newf->numpoints]);
        newf->numpoints++;
    }

    /* copy second polygon */
    for (l = (j + 1) % f2->numpoints; l != j; l = (l + 1) % f2->numpoints) {
        if (l == (j + 1) % f2->numpoints && !keep1)
            continue;
        VectorCopy(f2->p[l], newf->p[newf->numpoints]);
        newf->numpoints++;
    }

    return newf;
}

static face_t* TryMerge (face_t* f1, face_t* f2, const vec3_t planenormal)
{
    face_t* newf;
    winding_t* nw;

    if (!f1->w || !f2->w)
        return nullptr;
    if (f1->texinfo != f2->texinfo)
        return nullptr;
    if (f1->planenum != f2->planenum)   /* on front and back sides */
        return nullptr;
    if (f1->contentFlags != f2->contentFlags)
        return nullptr;

    nw = TryMergeWinding(f1->w, f2->w, planenormal);
    if (!nw)
        return nullptr;

    c_merge++;
    newf = NewFaceFromFace(f1);
    newf->w = nw;

    f1->merged = newf;
    f2->merged = newf;

    return newf;
}

static void MergeNodeFaces (node_t* node)
{
    face_t* f1;

    for (f1 = node->faces; f1; f1 = f1->next) {
        face_t* f2;
        if (f1->merged || f1->split[0] || f1->split[1])
            continue;
        for (f2 = node->faces; f2 != f1; f2 = f2->next) {
            const plane_t* plane = &mapplanes[node->planenum];
            face_t* merged;
            face_t* end;

            if (f2->merged || f2->split[0] || f2->split[1])
                continue;

            merged = TryMerge(f1, f2, plane->normal);
            if (!merged)
                continue;

            /* add merged to the end of the node face list
             * so it will be checked against all the faces again */
            for (end = node->faces; end->next; end = end->next);

            merged->next = nullptr;
            end->next = merged;
            break;
        }
    }
}

/*===================================================================== */

static void SubdivideFace (node_t* node, face_t* f)
{
    if (f->merged)
        return;

    /* special (non-surface cached) faces don't need subdivision */
    const dBspTexinfo_t* tex = &curTile->texinfo[f->texinfo];
    if (tex->surfaceFlags & SURF_WARP)
        return;

    for (int axis = 0; axis < 2; axis++) {
        while (1) {
            const winding_t* w = f->w;
            winding_t* frontw, *backw;
            float mins = 999999;
            float maxs = -999999;
            vec3_t temp;
            vec_t v;

            VectorCopy(tex->vecs[axis], temp);
            for (int i = 0; i < w->numpoints; i++) {
                v = DotProduct(w->p[i], temp);
                if (v < mins)
                    mins = v;
                if (v > maxs)
                    maxs = v;
            }

            /* no bsp subdivide for this winding? */
            if (maxs - mins <= config.subdivideSize)
                break;

            /* split it */
            c_subdivide++;

            v = VectorNormalize(temp);

            vec_t dist = (mins + config.subdivideSize - 16) / v;

            ClipWindingEpsilon(w, temp, dist, ON_EPSILON, &frontw, &backw);
            if (!frontw || !backw)
                Sys_Error("SubdivideFace: didn't split the polygon (texture: '%s')",
                    tex->texture);

            f->split[0] = NewFaceFromFace(f);
            f->split[0]->w = frontw;
            f->split[0]->next = node->faces;
            node->faces = f->split[0];

            f->split[1] = NewFaceFromFace(f);
            f->split[1]->w = backw;
            f->split[1]->next = node->faces;
            node->faces = f->split[1];

            SubdivideFace(node, f->split[0]);
            SubdivideFace(node, f->split[1]);
            return;
        }
    }
}

static void SubdivideNodeFaces (node_t* node)
{
    face_t* f;

    for (f = node->faces; f; f = f->next)
        SubdivideFace(node, f);
}

static int c_nodefaces;

static face_t* FaceFromPortal (portal_t* p, bool pside)
{
    face_t* f;
    side_t* side = p->side;

    /* portal does not bridge different visible contents */
    if (!side)
        return nullptr;

    /* nodraw/caulk faces */
    if (side->surfaceFlags & SURF_NODRAW)
        return nullptr;

    f = AllocFace();

    f->texinfo = side->texinfo;
    f->planenum = (side->planenum & ~1) | pside;
    f->portal = p;

    if ((p->nodes[pside]->contentFlags & CONTENTS_WINDOW)
     && VisibleContents(p->nodes[!pside]->contentFlags ^ p->nodes[pside]->contentFlags) == CONTENTS_WINDOW)
        return nullptr; /* don't show insides of windows */

    /* do back-clipping */
    if (!config.nobackclip && mapplanes[f->planenum].normal[2] < -0.9) {
        /* this face is not visible from birds view - optimize away
         * but only if it's not light emitting surface */
        const entity_t* e = &entities[side->brush->entitynum];
        if (!Q_streq(ValueForKey(e, "classname"), "func_rotating")) {
            if (!(curTile->texinfo[f->texinfo].surfaceFlags & SURF_LIGHT)) {
                /* e.g. water surfaces are removed if we set the surfaceFlags
                 * to SURF_NODRAW for this side */
                /*side->surfaceFlags |= SURF_NODRAW;*/
                return nullptr;
            }
        }
    }

    if (pside) {
        f->w = ReverseWinding(p->winding);
        f->contentFlags = p->nodes[1]->contentFlags;
    } else {
        f->w = CopyWinding(p->winding);
        f->contentFlags = p->nodes[0]->contentFlags;
    }
    return f;
}


static void MakeFaces_r (node_t* node)
{
    portal_t* p;

    /* recurse down to leafs */
    if (node->planenum != PLANENUM_LEAF) {
        MakeFaces_r(node->children[0]);
        MakeFaces_r(node->children[1]);

        /* merge together all visible faces on the node */
        if (!config.nomerge)
            MergeNodeFaces(node);
        if (!config.nosubdiv)
            SubdivideNodeFaces(node);

        return;
    }

    /* solid leafs never have visible faces */
    if (node->contentFlags & CONTENTS_SOLID)
        return;

    /* see which portals are valid */
    for (p = node->portals; p;) {
        const int pside = (p->nodes[1] == node);

        p->face[pside] = FaceFromPortal(p, pside);
        if (p->face[pside]) {
            c_nodefaces++;
            p->face[pside]->next = p->onnode->faces;
            p->onnode->faces = p->face[pside];
        }
        p = p->next[pside];
    }
}

void MakeFaces (node_t* node)
{
    Verb_Printf(VERB_EXTRA, "--- MakeFaces ---\n");
    c_merge = 0;
    c_subdivide = 0;
    c_nodefaces = 0;

    MakeFaces_r(node);

    Verb_Printf(VERB_EXTRA, "%5i makefaces\n", c_nodefaces);
    Verb_Printf(VERB_EXTRA, "%5i merged\n", c_merge);
    Verb_Printf(VERB_EXTRA, "%5i subdivided\n", c_subdivide);
}