tr_polytope.cpp

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

Doom 3 GPL Source Code
Copyright (C) 1999-2011 id Software LLC, a ZeniMax Media company. 

This file is part of the Doom 3 GPL Source Code (?Doom 3 Source Code?).  

Doom 3 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 3 of the License, or
(at your option) any later version.

Doom 3 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 Doom 3 Source Code.  If not, see <http://www.gnu.org/licenses/>.

In addition, the Doom 3 Source Code is also subject to certain additional terms. You should have received a copy of these additional terms immediately following the terms and conditions of the GNU General Public License which accompanied the Doom 3 Source Code.  If not, please request a copy in writing from id Software at the address below.

If you have questions concerning this license or the applicable additional terms, you may contact in writing id Software LLC, c/o ZeniMax Media Inc., Suite 120, Rockville, Maryland 20850 USA.

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

#include "../idlib/precompiled.h"
#pragma hdrstop

#include "tr_local.h"

#define MAX_POLYTOPE_PLANES             6

/*
=====================
R_PolytopeSurface

Generate vertexes and indexes for a polytope, and optionally returns the polygon windings.
The positive sides of the planes will be visible.
=====================
*/
srfTriangles_t *R_PolytopeSurface( int numPlanes, const idPlane *planes, idWinding **windings ) {
        int i, j;
        srfTriangles_t *tri;
        idFixedWinding planeWindings[MAX_POLYTOPE_PLANES];
        int numVerts, numIndexes;

        if ( numPlanes > MAX_POLYTOPE_PLANES ) {
                common->Error( "R_PolytopeSurface: more than %d planes", MAX_POLYTOPE_PLANES );
        }

        numVerts = 0;
        numIndexes = 0;
        for ( i = 0; i < numPlanes; i++ ) {
                const idPlane &plane = planes[i];
                idFixedWinding &w = planeWindings[i];

                w.BaseForPlane( plane );
                for ( j = 0; j < numPlanes; j++ ) {
                        const idPlane &plane2 = planes[j];
                        if ( j == i ) {
                                continue;
                        }
                        if ( !w.ClipInPlace( -plane2, ON_EPSILON ) ) {
                                break;
                        }
                }
                if ( w.GetNumPoints() <= 2 ) {
                        continue;
                }
                numVerts += w.GetNumPoints();
                numIndexes += ( w.GetNumPoints() - 2 ) * 3;
        }

        // allocate the surface
        tri = R_AllocStaticTriSurf();
        R_AllocStaticTriSurfVerts( tri, numVerts );
        R_AllocStaticTriSurfIndexes( tri, numIndexes );

        // copy the data from the windings
        for ( i = 0; i < numPlanes; i++ ) {
                idFixedWinding &w = planeWindings[i];
                if ( !w.GetNumPoints() ) {
                        continue;
                }
                for ( j = 0 ; j < w.GetNumPoints() ; j++ ) {
                        tri->verts[tri->numVerts + j ].Clear();
                        tri->verts[tri->numVerts + j ].xyz = w[j].ToVec3();
                }

                for ( j = 1 ; j < w.GetNumPoints() - 1 ; j++ ) {
                        tri->indexes[ tri->numIndexes + 0 ] = tri->numVerts;
                        tri->indexes[ tri->numIndexes + 1 ] = tri->numVerts + j;
                        tri->indexes[ tri->numIndexes + 2 ] = tri->numVerts + j + 1;
                        tri->numIndexes += 3;
                }
                tri->numVerts += w.GetNumPoints();

                // optionally save the winding
                if ( windings ) {
                        windings[i] = new idWinding( w.GetNumPoints() );
                        *windings[i] = w;
                }
        }

        R_BoundTriSurf( tri );

        return tri;
}