Polygon* MeshBuilder::addPolygon()
{
Polygon* item = allocatePolygon();
item->create( this, m_this->polygons.size() );
m_this->polygons.add( item );
return item;
}
//-----------------------------------------------------------------------
ConvexBody::ConvexBody( const ConvexBody& cpy )
{
for ( size_t i = 0; i < cpy.getPolygonCount(); ++i )
{
Polygon *p = allocatePolygon();
*p = cpy.getPolygon( i );
mPolygons.push_back( p );
}
}
//-----------------------------------------------------------------------
void ConvexBody::allocateSpace( size_t numPolygons, size_t numVertices )
{
reset();
// allocate numPolygons polygons with each numVertices vertices
for ( size_t iPoly = 0; iPoly < numPolygons; ++iPoly )
{
Polygon *poly = allocatePolygon();
for ( size_t iVertex = 0; iVertex < numVertices; ++iVertex )
{
poly->insertVertex( Vector3::ZERO );
}
mPolygons.push_back( poly );
}
}
//-----------------------------------------------------------------------
void ConvexBody::clip( const Plane& pl, bool keepNegative )
{
if ( getPolygonCount() == 0 )
return;
// current will be used as the reference body
ConvexBody current;
current.moveDataFromBody(*this);
OgreAssert( this->getPolygonCount() == 0, "Body not empty!" );
OgreAssert( current.getPolygonCount() != 0, "Body empty!" );
// holds all intersection edges for the different polygons
Polygon::EdgeMap intersectionEdges;
// clip all polygons by the intersection plane
// add only valid or intersected polygons to *this
for ( size_t iPoly = 0; iPoly < current.getPolygonCount(); ++iPoly )
{
// fetch vertex count and ignore polygons with less than three vertices
// the polygon is not valid and won't be added
const size_t vertexCount = current.getVertexCount( iPoly );
if ( vertexCount < 3 )
continue;
// current polygon
const Polygon& p = current.getPolygon( iPoly );
// the polygon to assemble
Polygon *pNew = allocatePolygon();
// the intersection polygon (indeed it's an edge or it's empty)
Polygon *pIntersect = allocatePolygon();
// check if polygons lie inside or outside (or on the plane)
// for each vertex check where it is situated in regard to the plane
// three possibilities appear:
Plane::Side clipSide = keepNegative ? Plane::POSITIVE_SIDE : Plane::NEGATIVE_SIDE;
// - side is clipSide: vertex will be clipped
// - side is !clipSide: vertex will be untouched
// - side is NOSIDE: vertex will be untouched
Plane::Side *side = OGRE_ALLOC_T(Plane::Side, vertexCount, MEMCATEGORY_SCENE_CONTROL);
for ( size_t iVertex = 0; iVertex < vertexCount; ++iVertex )
{
side[ iVertex ] = pl.getSide( p.getVertex( iVertex ) );
}
// now we check the side combinations for the current and the next vertex
// four different combinations exist:
// - both points inside (or on the plane): keep the second (add it to the body)
// - both points outside: discard both (don't add them to the body)
// - first vertex is inside, second is outside: add the intersection point
// - first vertex is outside, second is inside: add the intersection point, then the second
for ( size_t iVertex = 0; iVertex < vertexCount; ++iVertex )
{
// determine the next vertex
size_t iNextVertex = ( iVertex + 1 ) % vertexCount;
const Vector3& vCurrent = p.getVertex( iVertex );
const Vector3& vNext = p.getVertex( iNextVertex );
// case 1: both points inside (store next)
if ( side[ iVertex ] != clipSide && // NEGATIVE or NONE
side[ iNextVertex ] != clipSide ) // NEGATIVE or NONE
{
// keep the second
pNew->insertVertex( vNext );
}
// case 3: inside -> outside (store intersection)
else if ( side[ iVertex ] != clipSide &&
side[ iNextVertex ] == clipSide )
{
// Do an intersection with the plane. We use a ray with a start point and a direction.
// The ray is forced to hit the plane with any option available (eigher current or next
// is the starting point)
// intersect from the outside vertex towards the inside one
Vector3 vDirection = vCurrent - vNext;
vDirection.normalise();
Ray ray( vNext, vDirection );
std::pair< bool, Real > intersect = ray.intersects( pl );
// store intersection
if ( intersect.first )
{
// convert distance to vector
Vector3 vIntersect = ray.getPoint( intersect.second );
// store intersection
pNew->insertVertex( vIntersect );
pIntersect->insertVertex( vIntersect );
}
}
// case 4: outside -> inside (store intersection, store next)
else if ( side[ iVertex ] == clipSide &&
side[ iNextVertex ] != clipSide )
{
// Do an intersection with the plane. We use a ray with a start point and a direction.
// The ray is forced to hit the plane with any option available (eigher current or next
// is the starting point)
// intersect from the outside vertex towards the inside one
Vector3 vDirection = vNext - vCurrent;
vDirection.normalise();
Ray ray( vCurrent, vDirection );
std::pair< bool, Real > intersect = ray.intersects( pl );
// store intersection
if ( intersect.first )
{
// convert distance to vector
Vector3 vIntersect = ray.getPoint( intersect.second );
// store intersection
pNew->insertVertex( vIntersect );
pIntersect->insertVertex( vIntersect );
}
pNew->insertVertex( vNext );
}
// else:
// case 2: both outside (do nothing)
}
// insert the polygon only, if at least three vertices are present
if ( pNew->getVertexCount() >= 3 )
{
// in case there are double vertices, remove them
pNew->removeDuplicates();
// in case there are still at least three vertices, insert the polygon
if ( pNew->getVertexCount() >= 3 )
{
this->insertPolygon( pNew );
}
else
{
// delete pNew because it's empty or invalid
freePolygon(pNew);
pNew = 0;
}
}
else
{
// delete pNew because it's empty or invalid
freePolygon(pNew);
pNew = 0;
}
// insert intersection polygon only, if there are two vertices present
if ( pIntersect->getVertexCount() == 2 )
{
intersectionEdges.insert( Polygon::Edge( pIntersect->getVertex( 0 ),
pIntersect->getVertex( 1 ) ) );
}
// delete intersection polygon
// vertices were copied (if there were any)
freePolygon(pIntersect);
pIntersect = 0;
// delete side info
OGRE_FREE(side, MEMCATEGORY_SCENE_CONTROL);
side = 0;
}
// if the polygon was partially clipped, close it
// at least three edges are needed for a polygon
if ( intersectionEdges.size() >= 3 )
{
Polygon *pClosing = allocatePolygon();
// Analyze the intersection list and insert the intersection points in ccw order
// Each point is twice in the list because of the fact that we have a convex body
// with convex polygons. All we have to do is order the edges (an even-odd pair)
// in a ccw order. The plane normal shows us the direction.
Polygon::EdgeMap::iterator it = intersectionEdges.begin();
// check the cross product of the first two edges
Vector3 vFirst = it->first;
Vector3 vSecond = it->second;
// remove inserted edge
intersectionEdges.erase( it );
Vector3 vNext;
// find mating edge
if (findAndEraseEdgePair(vSecond, intersectionEdges, vNext))
{
// detect the orientation
// the polygon must have the same normal direction as the plane and then n
Vector3 vCross = ( vFirst - vSecond ).crossProduct( vNext - vSecond );
bool frontside = ( pl.normal ).directionEquals( vCross, Degree( 1 ) );
// first inserted vertex
Vector3 firstVertex;
// currently inserted vertex
Vector3 currentVertex;
// direction equals -> front side (walk ccw)
if ( frontside )
{
// start with next as first vertex, then second, then first and continue with first to walk ccw
pClosing->insertVertex( vNext );
pClosing->insertVertex( vSecond );
pClosing->insertVertex( vFirst );
firstVertex = vNext;
currentVertex = vFirst;
#ifdef _DEBUG_INTERSECTION_LIST
std::cout << "Plane: n=" << pl.normal << ", d=" << pl.d << std::endl;
std::cout << "First inserted vertex: " << *next << std::endl;
std::cout << "Second inserted vertex: " << *vSecond << std::endl;
std::cout << "Third inserted vertex: " << *vFirst << std::endl;
#endif
}
// direction does not equal -> back side (walk cw)
else
{
// start with first as first vertex, then second, then next and continue with next to walk ccw
pClosing->insertVertex( vFirst );
pClosing->insertVertex( vSecond );
pClosing->insertVertex( vNext );
firstVertex = vFirst;
currentVertex = vNext;
#ifdef _DEBUG_INTERSECTION_LIST
std::cout << "Plane: n=" << pl.normal << ", d=" << pl.d << std::endl;
std::cout << "First inserted vertex: " << *vFirst << std::endl;
std::cout << "Second inserted vertex: " << *vSecond << std::endl;
std::cout << "Third inserted vertex: " << *next << std::endl;
#endif
}
// search mating edges that have a point in common
// continue this operation as long as edges are present
while ( !intersectionEdges.empty() )
{
if (findAndEraseEdgePair(currentVertex, intersectionEdges, vNext))
{
// insert only if it's not the last (which equals the first) vertex
if ( !intersectionEdges.empty() )
{
currentVertex = vNext;
pClosing->insertVertex( vNext );
}
}
else
{
// degenerated...
break;
}
} // while intersectionEdges not empty
// insert polygon (may be degenerated!)
this->insertPolygon( pClosing );
}
// mating intersection edge NOT found!
else
{
freePolygon(pClosing);
}
} // if intersectionEdges contains more than three elements
}
//-----------------------------------------------------------------------
void ConvexBody::mergePolygons( void )
{
// Merge all polygons that lay in the same plane as one big polygon.
// A convex body does not have two separate regions (separated by polygons
// with different normals) where the same normal occurs, so we can simply
// search all similar normals of a polygon. Two different options are
// possible when the normals fit:
// - the two polygons are neighbors
// - the two polygons aren't neighbors (but a third, fourth,.. polygon lays
// in between)
// Signals if the body holds polygons which aren't neighbors but have the same
// normal. That means another step has to be processed.
bool bDirty = false;
for ( size_t iPolyA = 0; iPolyA < getPolygonCount(); ++iPolyA )
{
// ??
OgreAssert( iPolyA >= 0, "strange..." );
for ( size_t iPolyB = iPolyA+1; iPolyB < getPolygonCount(); ++iPolyB )
{
const Vector3& n1 = getNormal( iPolyA );
const Vector3& n2 = getNormal( iPolyB );
// if the normals point into the same direction
if ( n1.directionEquals( n2, Radian( Degree( 0.00001 ) ) ) )
{
// indicates if a neighbor has been found and joined
bool bFound = false;
// search the two fitting vertices (if there are any) for the common edge
const size_t numVerticesA = getVertexCount( iPolyA );
for ( size_t iVertexA = 0; iVertexA < numVerticesA; ++iVertexA )
{
const size_t numVerticesB = getVertexCount( iPolyB );
for ( size_t iVertexB = 0; iVertexB < numVerticesB; ++iVertexB )
{
const Vector3& aCurrent = getVertex( iPolyA, iVertexA );
const Vector3& aNext = getVertex( iPolyA, (iVertexA + 1) % getVertexCount( iPolyA ) );
const Vector3& bCurrent = getVertex( iPolyB, iVertexB );
const Vector3& bNext = getVertex( iPolyB, (iVertexB + 1) % getVertexCount( iPolyB ) );
// if the edge is the same the current vertex of A has to be equal to the next of B and the other
// way round
if ( aCurrent.positionEquals(bNext) &&
bCurrent.positionEquals(aNext))
{
// polygons are neighbors, assemble new one
Polygon *pNew = allocatePolygon();
// insert all vertices of A up to the join (including the common vertex, ignoring
// whether the first vertex of A may be a shared vertex)
for ( size_t i = 0; i <= iVertexA; ++i )
{
pNew->insertVertex( getVertex( iPolyA, i%numVerticesA ) );
}
// insert all vertices of B _after_ the join to the end
for ( size_t i = iVertexB + 2; i < numVerticesB; ++i )
{
pNew->insertVertex( getVertex( iPolyB, i ) );
}
// insert all vertices of B from the beginning up to the join (including the common vertex
// and excluding the first vertex if the first is part of the shared edge)
for ( size_t i = 0; i <= iVertexB; ++i )
{
pNew->insertVertex( getVertex( iPolyB, i%numVerticesB ) );
}
// insert all vertices of A _after_ the join to the end
for ( size_t i = iVertexA + 2; i < numVerticesA; ++i )
{
pNew->insertVertex( getVertex( iPolyA, i ) );
}
// in case there are double vertices (in special cases), remove them
for ( size_t i = 0; i < pNew->getVertexCount(); ++i )
{
const Vector3& a = pNew->getVertex( i );
const Vector3& b = pNew->getVertex( (i + 1) % pNew->getVertexCount() );
// if the two vertices are the same...
if (a.positionEquals(b))
{
// remove a
pNew->deleteVertex( i );
// decrement counter
--i;
}
}
// delete the two old ones
OgreAssert( iPolyA != iPolyB, "PolyA and polyB are the same!" );
// polyB is always higher than polyA, so delete polyB first
deletePolygon( iPolyB );
deletePolygon( iPolyA );
// continue with next (current is deleted, so don't jump to the next after the next)
--iPolyA;
--iPolyB;
// insert new polygon
insertPolygon( pNew );
bFound = true;
break;
}
}
if ( bFound )
{
break;
}
}
if ( bFound == false )
{
// there are two polygons available with the same normal direction, but they
// could not be merged into one single because of no shared edge
bDirty = true;
break;
}
}
}
}
// recursion to merge the previous non-neighbors
if ( bDirty )
{
mergePolygons();
}
}
//-----------------------------------------------------------------------
void ConvexBody::extend(const Vector3& pt)
{
// Erase all polygons facing towards the point. For all edges that
// are not removed twice (once in AB and once BA direction) build a
// convex polygon (triangle) with the point.
Polygon::EdgeMap edgeMap;
for ( size_t i = 0; i < getPolygonCount(); ++i )
{
const Vector3& normal = getNormal( i );
// direction of the point in regard to the polygon
// the polygon is planar so we can take an arbitrary vertex
Vector3 ptDir = pt - getVertex( i, 0 );
ptDir.normalise();
// remove polygon if dot product is greater or equals null.
if ( normal.dotProduct( ptDir ) >= 0 )
{
// store edges (copy them because if the polygon is deleted
// its vertices are also deleted)
storeEdgesOfPolygon( i, &edgeMap );
// remove polygon
deletePolygon( i );
// decrement iterator because of deleted polygon
--i;
}
}
// point is already a part of the hull (point lies inside)
if ( edgeMap.empty() )
return;
// remove the edges that are twice in the list (once from each side: AB,BA)
Polygon::EdgeMap::iterator it;
// iterate from first to the element before the last one
for (Polygon::EdgeMap::iterator itStart = edgeMap.begin();
itStart != edgeMap.end(); )
{
// compare with iterator + 1 to end
// don't need to skip last entry in itStart since omitted in inner loop
it = itStart;
++it;
bool erased = false;
// iterate from itStart+1 to the element before the last one
for ( ; it != edgeMap.end(); ++it )
{
if (itStart->first.positionEquals(it->second) &&
itStart->second.positionEquals(it->first))
{
edgeMap.erase(it);
// increment itStart before deletion (iterator invalidation)
Polygon::EdgeMap::iterator delistart = itStart++;
edgeMap.erase(delistart);
erased = true;
break; // found and erased
}
}
// increment itStart if we didn't do it when erasing
if (!erased)
++itStart;
}
// use the remaining edges to build triangles with the point
// the vertices of the edges are in ccw order (edgePtA-edgePtB-point
// to form a ccw polygon)
while ( !edgeMap.empty() )
{
Polygon::EdgeMap::iterator mapIt = edgeMap.begin();
// build polygon it.first, it.second, point
Polygon *p = allocatePolygon();
p->insertVertex(mapIt->first);
p->insertVertex(mapIt->second);
p->insertVertex( pt );
// attach polygon to body
insertPolygon( p );
// erase the vertices from the list
// pointers are now held by the polygon
edgeMap.erase( mapIt );
}
}
//-----------------------------------------------------------------------
void ConvexBody::define(const AxisAlignedBox& aab)
{
// ordering of the AAB points:
// 1-----2
// /| /|
// / | / |
// 5-----4 |
// | 0--|--3
// | / | /
// |/ |/
// 6-----7
const Vector3& min = aab.getMinimum();
const Vector3& max = aab.getMaximum();
Vector3 currentVertex = min;
Polygon *poly;
// reset body
reset();
// far
poly = allocatePolygon();
poly->insertVertex( currentVertex ); // 0
currentVertex.y = max.y;
poly->insertVertex( currentVertex ); // 1
currentVertex.x = max.x;
poly->insertVertex( currentVertex ); // 2
currentVertex.y = min.y;
poly->insertVertex( currentVertex ); // 3
insertPolygon( poly );
// right
poly = allocatePolygon();
poly->insertVertex( currentVertex ); // 3
currentVertex.y = max.y;
poly->insertVertex( currentVertex ); // 2
currentVertex.z = max.z;
poly->insertVertex( currentVertex ); // 4
currentVertex.y = min.y;
poly->insertVertex( currentVertex ); // 7
insertPolygon( poly );
// near
poly = allocatePolygon();
poly->insertVertex( currentVertex ); // 7
currentVertex.y = max.y;
poly->insertVertex( currentVertex ); // 4
currentVertex.x = min.x;
poly->insertVertex( currentVertex ); // 5
currentVertex.y = min.y;
poly->insertVertex( currentVertex ); // 6
insertPolygon( poly );
// left
poly = allocatePolygon();
poly->insertVertex( currentVertex ); // 6
currentVertex.y = max.y;
poly->insertVertex( currentVertex ); // 5
currentVertex.z = min.z;
poly->insertVertex( currentVertex ); // 1
currentVertex.y = min.y;
poly->insertVertex( currentVertex ); // 0
insertPolygon( poly );
// bottom
poly = allocatePolygon();
poly->insertVertex( currentVertex ); // 0
currentVertex.x = max.x;
poly->insertVertex( currentVertex ); // 3
currentVertex.z = max.z;
poly->insertVertex( currentVertex ); // 7
currentVertex.x = min.x;
poly->insertVertex( currentVertex ); // 6
insertPolygon( poly );
// top
poly = allocatePolygon();
currentVertex = max;
poly->insertVertex( currentVertex ); // 4
currentVertex.z = min.z;
poly->insertVertex( currentVertex ); // 2
currentVertex.x = min.x;
poly->insertVertex( currentVertex ); // 1
currentVertex.z = max.z;
poly->insertVertex( currentVertex ); // 5
insertPolygon( poly );
}
//-----------------------------------------------------------------------
void ConvexBody::define(const Frustum& frustum)
{
// ordering of the points:
// near (0-3), far (4-7); each (top-right, top-left, bottom-left, bottom-right)
// 5-----4
// /| /|
// / | / |
// 1-----0 |
// | 6--|--7
// | / | /
// |/ |/
// 2-----3
const Vector3 *pts = frustum.getWorldSpaceCorners();
/// reset ConvexBody
reset();
/// update vertices: near, far, left, right, bottom, top; fill in ccw
Polygon *poly;
// near
poly = allocatePolygon();
poly->insertVertex( pts[0] );
poly->insertVertex( pts[1] );
poly->insertVertex( pts[2] );
poly->insertVertex( pts[3] );
mPolygons.push_back( poly );
// far
poly = allocatePolygon();
poly->insertVertex( pts[5] );
poly->insertVertex( pts[4] );
poly->insertVertex( pts[7] );
poly->insertVertex( pts[6] );
mPolygons.push_back( poly );
// left
poly = allocatePolygon();
poly->insertVertex( pts[5] );
poly->insertVertex( pts[6] );
poly->insertVertex( pts[2] );
poly->insertVertex( pts[1] );
mPolygons.push_back( poly );
// right
poly = allocatePolygon();
poly->insertVertex( pts[4] );
poly->insertVertex( pts[0] );
poly->insertVertex( pts[3] );
poly->insertVertex( pts[7] );
mPolygons.push_back( poly );
// bottom
poly = allocatePolygon();
poly->insertVertex( pts[6] );
poly->insertVertex( pts[7] );
poly->insertVertex( pts[3] );
poly->insertVertex( pts[2] );
mPolygons.push_back( poly );
// top
poly = allocatePolygon();
poly->insertVertex( pts[4] );
poly->insertVertex( pts[5] );
poly->insertVertex( pts[1] );
poly->insertVertex( pts[0] );
mPolygons.push_back( poly );
}
//-----------------------------------------------------------------------
void ConvexBody::define( const Vector3 corners[8] )
{
// ordering of the AAB points:
// 1-----2
// /| /|
// / | / |
// 5-----4 |
// | 0--|--3
// | / | /
// |/ |/
// 6-----7
Polygon *poly;
// reset body
reset();
// far
poly = allocatePolygon();
poly->insertVertex( corners[0] ); // 0
poly->insertVertex( corners[1] ); // 1
poly->insertVertex( corners[2] ); // 2
poly->insertVertex( corners[3] ); // 3
insertPolygon( poly );
// right
poly = allocatePolygon();
poly->insertVertex( corners[3] ); // 3
poly->insertVertex( corners[2] ); // 2
poly->insertVertex( corners[4] ); // 4
poly->insertVertex( corners[7] ); // 7
insertPolygon( poly );
// near
poly = allocatePolygon();
poly->insertVertex( corners[7] ); // 7
poly->insertVertex( corners[4] ); // 4
poly->insertVertex( corners[5] ); // 5
poly->insertVertex( corners[6] ); // 6
insertPolygon( poly );
// left
poly = allocatePolygon();
poly->insertVertex( corners[6] ); // 6
poly->insertVertex( corners[5] ); // 5
poly->insertVertex( corners[1] ); // 1
poly->insertVertex( corners[0] ); // 0
insertPolygon( poly );
// bottom
poly = allocatePolygon();
poly->insertVertex( corners[0] ); // 0
poly->insertVertex( corners[3] ); // 3
poly->insertVertex( corners[7] ); // 7
poly->insertVertex( corners[6] ); // 6
insertPolygon( poly );
// top
poly = allocatePolygon();
poly->insertVertex( corners[4] ); // 4
poly->insertVertex( corners[2] ); // 2
poly->insertVertex( corners[1] ); // 1
poly->insertVertex( corners[5] ); // 5
insertPolygon( poly );
}
