CSG.CPP

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/*
===========================================================================
Copyright (C) 1999-2005 Id Software, Inc.

This file is part of Quake III Arena source code.

Quake III Arena source code 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.

Quake III Arena source code 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 Foobar; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
===========================================================================
*/

#include "stdafx.h"
#include "qe3.h"
#include "winding.h"


/*
=============
CSG_MakeHollow
=============
*/

void Brush_Scale(brush_t* b)
{
  for (face_t* f = b->brush_faces ; f ; f=f->next)
  {
      for (int i=0 ; i<3 ; i++)
    {
      VectorScale (f->planepts[i], g_qeglobals.d_gridsize, f->planepts[i]);
    }
  }
}

void CSG_MakeHollow (void)
{
    brush_t     *b, *front, *back, *next;
    face_t      *f;
    face_t      split;
    vec3_t      move;
    int         i;

    for (b = selected_brushes.next ; b != &selected_brushes ; b=next)
    {
        next = b->next;

    if (b->owner->eclass->fixedsize || b->patchBrush || b->terrainBrush || b->hiddenBrush)
          continue;

        for (f = b->brush_faces ; f ; f=f->next)
        {
            split = *f;
            VectorScale (f->plane.normal, g_qeglobals.d_gridsize, move);
            for (i=0 ; i<3 ; i++)
                VectorSubtract (split.planepts[i], move, split.planepts[i]);

            Brush_SplitBrushByFace (b, &split, &front, &back);
            if (back)
                Brush_Free (back);
            if (front)
                Brush_AddToList (front, &selected_brushes);
        }
        Brush_Free (b);
    }
    Sys_UpdateWindows (W_ALL);
}

/*
=============
Brush_Merge

 Returns a new brush that is created by merging brush1 and brush2.
 May return NULL if brush1 and brush2 do not create a convex brush when merged.
 The input brushes brush1 and brush2 stay intact.

 if onlyshape is true then the merge is allowed based on the shape only
 otherwise the texture/shader references of faces in the same plane have to
 be the same as well.
=============
*/
brush_t *Brush_Merge(brush_t *brush1, brush_t *brush2, int onlyshape)
{
    int i, shared;
    brush_t *newbrush;
    face_t *face1, *face2, *newface, *f;

    // check for bounding box overlapp
    for (i = 0; i < 3; i++)
    {
        if (brush1->mins[i] > brush2->maxs[i] + ON_EPSILON
                || brush1->maxs[i] < brush2->mins[i] - ON_EPSILON)
        {
            // never merge if the brushes overlap
            return NULL;
        }
    }
    //
    shared = 0;
    // check if the new brush would be convex... flipped planes make a brush non-convex
    for (face1 = brush1->brush_faces; face1; face1 = face1->next)
    {
        // don't check the faces of brush 1 and 2 touching each other
        for (face2 = brush2->brush_faces; face2; face2 = face2->next)
        {
            if (Plane_Equal(&face1->plane, &face2->plane, true))
            {
                shared++;
                // there may only be ONE shared side
                if (shared > 1)
                    return NULL;
                break;
            }
        }
        // if this face plane is shared
        if (face2) continue;
        //
        for (face2 = brush2->brush_faces; face2; face2 = face2->next)
        {
            // don't check the faces of brush 1 and 2 touching each other
            for (f = brush1->brush_faces; f; f = f->next)
            {
                if (Plane_Equal(&face2->plane, &f->plane, true)) break;
            }
            if (f)
                continue;
            //
            if (Plane_Equal(&face1->plane, &face2->plane, false))
            {
                //if the texture/shader references should be the same but are not
                if (!onlyshape && stricmp(face1->texdef.name, face2->texdef.name) != 0) return NULL;
                continue;
            }
            //
            if (Winding_PlanesConcave(face1->face_winding, face2->face_winding,
                                    face1->plane.normal, face2->plane.normal,
                                    face1->plane.dist, face2->plane.dist))
            {
                return NULL;
            } //end if
        } //end for
    } //end for
    //
    newbrush = Brush_Alloc();
    //
    for (face1 = brush1->brush_faces; face1; face1 = face1->next)
    {
        // don't add the faces of brush 1 and 2 touching each other
        for (face2 = brush2->brush_faces; face2; face2 = face2->next)
        {
            if (Plane_Equal(&face1->plane, &face2->plane, true))
                break;
        }
        if (face2)
            continue;
        // don't add faces with the same plane twice
        for (f = newbrush->brush_faces; f; f = f->next)
        {
            if (Plane_Equal(&face1->plane, &f->plane, false))
                break;
            if (Plane_Equal(&face1->plane, &f->plane, true))
                break;
        }
        if (f)
            continue;
        //
        newface = Face_Alloc();
        newface->texdef = face1->texdef;
        VectorCopy(face1->planepts[0], newface->planepts[0]);
        VectorCopy(face1->planepts[1], newface->planepts[1]);
        VectorCopy(face1->planepts[2], newface->planepts[2]);
        newface->plane = face1->plane;
        newface->next = newbrush->brush_faces;
        newbrush->brush_faces = newface;
    }
    //
    for (face2 = brush2->brush_faces; face2; face2 = face2->next)
    {
        // don't add the faces of brush 1 and 2 touching each other
        for (face1 = brush1->brush_faces; face1; face1 = face1->next)
        {
            if (Plane_Equal(&face2->plane, &face1->plane, true))
                break;
        }
        if (face1)
            continue;
        // don't add faces with the same plane twice
        for (f = newbrush->brush_faces; f; f = f->next)
        {
            if (Plane_Equal(&face2->plane, &f->plane, false))
                break;
            if (Plane_Equal(&face2->plane, &f->plane, true))
                break;
        }
        if (f)
            continue;
        //
        newface = Face_Alloc();
        newface->texdef = face2->texdef;
        VectorCopy(face2->planepts[0], newface->planepts[0]);
        VectorCopy(face2->planepts[1], newface->planepts[1]);
        VectorCopy(face2->planepts[2], newface->planepts[2]);
        newface->plane = face2->plane;
        newface->next = newbrush->brush_faces;
        newbrush->brush_faces = newface;
    }
    // link the new brush to an entity
    Entity_LinkBrush (brush1->owner, newbrush);
    // build windings for the faces
    Brush_BuildWindings( newbrush, false);
    return newbrush;
}

/*
=============
Brush_MergeListPairs

  Returns a list with merged brushes.
  Tries to merge brushes pair wise.
  The input list is destroyed.
  Input and output should be a single linked list using .next
=============
*/
brush_t *Brush_MergeListPairs(brush_t *brushlist, int onlyshape)
{
    int nummerges, merged;
    brush_t *b1, *b2, *tail, *newbrush, *newbrushlist;
    brush_t *lastb2;

    if (!brushlist) return NULL;

    nummerges = 0;
    do
    {
        for (tail = brushlist; tail; tail = tail->next)
        {
            if (!tail->next) break;
        }
        merged = 0;
        newbrushlist = NULL;
        for (b1 = brushlist; b1; b1 = brushlist)
        {
            lastb2 = b1;
            for (b2 = b1->next; b2; b2 = b2->next)
            {
                newbrush = Brush_Merge(b1, b2, onlyshape);
                if (newbrush)
                {
                    tail->next = newbrush;
                    lastb2->next = b2->next;
                    brushlist = brushlist->next;
                    b1->next = b1->prev = NULL;
                    b2->next = b2->prev = NULL;
                    Brush_Free(b1);
                    Brush_Free(b2);
                    for (tail = brushlist; tail; tail = tail->next)
                    {
                        if (!tail->next) break;
                    } //end for
                    merged++;
                    nummerges++;
                    break;
                }
                lastb2 = b2;
            }
            //if b1 can't be merged with any of the other brushes
            if (!b2)
            {
                brushlist = brushlist->next;
                //keep b1
                b1->next = newbrushlist;
                newbrushlist = b1;
            }
        }
        brushlist = newbrushlist;
    } while(merged);
    return newbrushlist;
}

/*
=============
Brush_MergeList

 Tries to merge all brushes in the list into one new brush.
 The input brush list stays intact.
 Returns NULL if no merged brush can be created.
 To create a new brush the brushes in the list may not overlap and
 the outer faces of the brushes together should make a new convex brush.

 if onlyshape is true then the merge is allowed based on the shape only
 otherwise the texture/shader references of faces in the same plane have to
 be the same as well.
=============
*/
brush_t *Brush_MergeList(brush_t *brushlist, int onlyshape)
{
    brush_t *brush1, *brush2, *brush3, *newbrush;
    face_t *face1, *face2, *face3, *newface, *f;

    if (!brushlist) return NULL;
    for (brush1 = brushlist; brush1; brush1 = brush1->next)
    {
        // check if the new brush would be convex... flipped planes make a brush concave
        for (face1 = brush1->brush_faces; face1; face1 = face1->next)
        {
            // don't check face1 if it touches another brush
            for (brush2 = brushlist; brush2; brush2 = brush2->next)
            {
                if (brush2 == brush1) continue;
                for (face2 = brush2->brush_faces; face2; face2 = face2->next)
                {
                    if (Plane_Equal(&face1->plane, &face2->plane, true))
                    {
                        break;
                    }
                }
                if (face2) break;
            }
            // if face1 touches another brush
            if (brush2) continue;
            //
            for (brush2 = brush1->next; brush2; brush2 = brush2->next)
            {
                // don't check the faces of brush 2 touching another brush
                for (face2 = brush2->brush_faces; face2; face2 = face2->next)
                {
                    for (brush3 = brushlist; brush3; brush3 = brush3->next)
                    {
                        if (brush3 == brush2) continue;
                        for (face3 = brush3->brush_faces; face3; face3 = face3->next)
                        {
                            if (Plane_Equal(&face2->plane, &face3->plane, true)) break;
                        }
                        if (face3) break;
                    }
                    // if face2 touches another brush
                    if (brush3) continue;
                    //
                    if (Plane_Equal(&face1->plane, &face2->plane, false))
                    {
                        //if the texture/shader references should be the same but are not
                        if (!onlyshape && stricmp(face1->texdef.name, face2->texdef.name) != 0) return NULL;
                        continue;
                    }
                    //
                    if (Winding_PlanesConcave(face1->face_winding, face2->face_winding,
                                            face1->plane.normal, face2->plane.normal,
                                            face1->plane.dist, face2->plane.dist))
                    {
                        return NULL;
                    }
                }
            }
        }
    }
    //
    newbrush = Brush_Alloc();
    //
    for (brush1 = brushlist; brush1; brush1 = brush1->next)
    {
        for (face1 = brush1->brush_faces; face1; face1 = face1->next)
        {
            // don't add face1 to the new brush if it touches another brush
            for (brush2 = brushlist; brush2; brush2 = brush2->next)
            {
                if (brush2 == brush1) continue;
                for (face2 = brush2->brush_faces; face2; face2 = face2->next)
                {
                    if (Plane_Equal(&face1->plane, &face2->plane, true))
                    {
                        break;
                    }
                }
                if (face2) break;
            }
            if (brush2) continue;
            // don't add faces with the same plane twice
            for (f = newbrush->brush_faces; f; f = f->next)
            {
                if (Plane_Equal(&face1->plane, &f->plane, false))
                    break;
                if (Plane_Equal(&face1->plane, &f->plane, true))
                    break;
            }
            if (f)
                continue;
            //
            newface = Face_Alloc();
            newface->texdef = face1->texdef;
            VectorCopy(face1->planepts[0], newface->planepts[0]);
            VectorCopy(face1->planepts[1], newface->planepts[1]);
            VectorCopy(face1->planepts[2], newface->planepts[2]);
            newface->plane = face1->plane;
            newface->next = newbrush->brush_faces;
            newbrush->brush_faces = newface;
        }
    }
    // link the new brush to an entity
    Entity_LinkBrush (brushlist->owner, newbrush);
    // build windings for the faces
    Brush_BuildWindings( newbrush, false);
    return newbrush;
}

/*
=============
Brush_Subtract

 Returns a list of brushes that remain after B is subtracted from A.
 May by empty if A is contained inside B.
 The originals are undisturbed.
=============
*/
brush_t *Brush_Subtract(brush_t *a, brush_t *b)
{
    // a - b = out (list)
    brush_t *front, *back;
    brush_t *in, *out, *next;
    face_t *f;

    in = a;
    out = NULL;
    for (f = b->brush_faces; f && in; f = f->next)
    {
        Brush_SplitBrushByFace(in, f, &front, &back);
        if (in != a) Brush_Free(in);
        if (front)
        {   // add to list
            front->next = out;
            out = front;
        }
        in = back;
    }
    //NOTE: in != a just in case brush b has no faces
    if (in && in != a)
    {
        Brush_Free(in);
    }
    else
    {   //didn't really intersect
        for (b = out; b; b = next)
        {
            next = b->next;
            b->next = b->prev = NULL;
            Brush_Free(b);
        }
        return a;
    }
    return out;
}

/*
=============
CSG_Subtract
=============
*/
void CSG_Subtract (void)
{
    brush_t     *b, *s, *fragments, *nextfragment, *frag, *next, *snext;
    brush_t     fragmentlist;
    int         i, numfragments, numbrushes;

    Sys_Printf ("Subtracting...\n");

    if (selected_brushes.next == &selected_brushes)
    {
        Sys_Printf("No brushes selected.\n");
        return;
    }

    fragmentlist.next = &fragmentlist;
    fragmentlist.prev = &fragmentlist;

    numfragments = 0;
    numbrushes = 0;
    for (b = selected_brushes.next ; b != &selected_brushes ; b=next)
    {
        next = b->next;

        if (b->owner->eclass->fixedsize)
            continue;   // can't use texture from a fixed entity, so don't subtract

        // chop all fragments further up
        for (s = fragmentlist.next; s != &fragmentlist; s = snext)
        {
            snext = s->next;

            for (i=0 ; i<3 ; i++)
                if (b->mins[i] >= s->maxs[i] - ON_EPSILON 
                || b->maxs[i] <= s->mins[i] + ON_EPSILON)
                    break;
            if (i != 3)
                continue;   // definately don't touch
            fragments = Brush_Subtract(s, b);
            // if the brushes did not really intersect
            if (fragments == s)
                continue;
            // try to merge fragments
            fragments = Brush_MergeListPairs(fragments, true);
            // add the fragments to the list
            for (frag = fragments; frag; frag = nextfragment)
            {
                nextfragment = frag->next;
                frag->next = NULL;
                frag->owner = s->owner;
                Brush_AddToList(frag, &fragmentlist);
            }
            // free the original brush
            Brush_Free(s);
        }

        // chop any active brushes up
        for (s = active_brushes.next; s != &active_brushes; s = snext)
        {
            snext = s->next;

            if (s->owner->eclass->fixedsize || s->patchBrush || s->terrainBrush || s->hiddenBrush)
                continue;

            //face_t *pFace = s->brush_faces;
            if (s->brush_faces->d_texture->bFromShader && (s->brush_faces->d_texture->nShaderFlags & QER_NOCARVE))
            {
                continue;
            }

            for (i=0 ; i<3 ; i++)
                if (b->mins[i] >= s->maxs[i] - ON_EPSILON 
                || b->maxs[i] <= s->mins[i] + ON_EPSILON)
                    break;
            if (i != 3)
                continue;   // definately don't touch

            fragments = Brush_Subtract(s, b);
            // if the brushes did not really intersect
            if (fragments == s)
                continue;
            //
            Undo_AddBrush(s);
            // one extra brush chopped up
            numbrushes++;
            // try to merge fragments
            fragments = Brush_MergeListPairs(fragments, true);
            // add the fragments to the list
            for (frag = fragments; frag; frag = nextfragment)
            {
                nextfragment = frag->next;
                frag->next = NULL;
                frag->owner = s->owner;
                Brush_AddToList(frag, &fragmentlist);
            }
            // free the original brush
            Brush_Free(s);
        }
    }

    // move all fragments to the active brush list
    for (frag = fragmentlist.next; frag != &fragmentlist; frag = nextfragment)
    {
        nextfragment = frag->next;
        numfragments++;
        Brush_RemoveFromList(frag);
        Brush_AddToList(frag, &active_brushes);
        Undo_EndBrush(frag);
    }

    if (numfragments == 0)
    {
        Sys_Printf("Selected brush%s did not intersect with any other brushes.\n",
                    (selected_brushes.next->next == &selected_brushes) ? "":"es");
        return;
    }
    Sys_Printf("done. (created %d fragment%s out of %d brush%s)\n", numfragments, (numfragments == 1)?"":"s",
                            numbrushes, (numbrushes == 1)?"":"es");
    Sys_UpdateWindows(W_ALL);
}

/*
=============
CSG_Merge
=============
*/
void CSG_Merge(void)
{
    brush_t *b, *next, *newlist, *newbrush;
    struct entity_s *owner;

    Sys_Printf ("Merging...\n");

    if (selected_brushes.next == &selected_brushes)
    {
        Sys_Printf("No brushes selected.\n");
        return;
    }

    if (selected_brushes.next->next == &selected_brushes)
    {
        Sys_Printf("At least two brushes have to be selected.\n");
        return;
    }

    owner = selected_brushes.next->owner;

    for (b = selected_brushes.next; b != &selected_brushes; b = next)
    {
        next = b->next;

        if (b->owner->eclass->fixedsize)
        {
            // can't use texture from a fixed entity, so don't subtract
            Sys_Printf("Cannot add fixed size entities.\n");
            return;
        }

        if (b->patchBrush)
        {
            Sys_Printf("Cannot add patches.\n");
            return;
        }
        if (b->terrainBrush)
        {
            Sys_Printf("Cannot add terrains.\n");
            return;
        }

        if (b->brush_faces->d_texture->bFromShader && (b->brush_faces->d_texture->nShaderFlags & QER_NOCARVE))
        {
            Sys_Printf("Cannot add brushes using shaders that don't allows CSG operations.\n");
            return;
        }

        if (b->owner != owner)
        {
            Sys_Printf("Cannot add brushes from different entities.\n");
            return;
        }

    }

    newlist = NULL;
    for (b = selected_brushes.next; b != &selected_brushes; b = next)
    {
        next = b->next;

        Brush_RemoveFromList(b);
        b->next = newlist;
        b->prev = NULL;
        newlist = b;
    }

    newbrush = Brush_MergeList(newlist, true);
    // if the new brush would not be convex
    if (!newbrush)
    {
        // add the brushes back into the selection
        for (b = newlist; b; b = next)
        {
            next = b->next;
            b->next = NULL;
            b->prev = NULL;
            Brush_AddToList(b, &selected_brushes);
        }
        Sys_Printf("Cannot add a set of brushes with a concave hull.\n");
        return;
    }
    // free the original brushes
    for (b = newlist; b; b = next)
    {
        next = b->next;
        b->next = NULL;
        b->prev = NULL;
        Brush_Free(b);
    }
    Brush_AddToList(newbrush, &selected_brushes);

    Sys_Printf ("done.\n");
    Sys_UpdateWindows (W_ALL);
}

---