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flightgear/src/FDM/groundcache.cxx
frohlich 5d1c390194 Modified Files: 
groundcache.cxx: Cheaper ray triangle intersection
2006-11-21 18:25:36 +00:00

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// groundcache.cxx -- carries a small subset of the scenegraph near the vehicle
//
// Written by Mathias Froehlich, started Nov 2004.
//
// Copyright (C) 2004 Mathias Froehlich - Mathias.Froehlich@web.de
//
// 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
//
// $Id$
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#include <float.h>
#include <plib/sg.h>
#include <osg/CullFace>
#include <osg/Drawable>
#include <osg/Geode>
#include <osg/Geometry>
#include <osg/TriangleFunctor>
#include <simgear/sg_inlines.h>
#include <simgear/constants.h>
#include <simgear/debug/logstream.hxx>
#include <simgear/math/sg_geodesy.hxx>
#include <simgear/scene/material/mat.hxx>
#include <simgear/scene/material/matlib.hxx>
#include <simgear/scene/util/SGNodeMasks.hxx>
#include <Main/globals.hxx>
#include <Scenery/scenery.hxx>
#include <Scenery/tilemgr.hxx>
#include <AIModel/AICarrier.hxx>
#include "flight.hxx"
#include "groundcache.hxx"
static inline bool
fgdRayTriangle(SGVec3d& x, const SGVec3d& point, const SGVec3d& dir,
const SGVec3d v[3])
{
double eps = 1e-4;
// Method based on the observation that we are looking for a
// point x that can be expressed in terms of the triangle points
// x = p_0 + \mu_1*(p_1 - p_0) + \mu_2*(p_2 - p_0)
// with 0 <= \mu_1, \mu_2 and \mu_1 + \mu_2 <= 1.
// OTOH it could be expressed in terms of the ray
// x = point + \lambda*dir
// Now we can compute \mu_i and \lambda.
// define
SGVec3d d1 = v[1] - v[0];
SGVec3d d2 = v[2] - v[0];
SGVec3d b = point - v[0];
// the vector in normal direction, but not normalized
SGVec3d d1crossd2 = cross(d1, d2);
double denom = -dot(dir, d1crossd2);
double signDenom = copysign(1, denom);
// return if paralell ??? FIXME what if paralell and in plane?
// may be we are ok below than anyway??
// if (SGMiscd::abs(denom) <= SGLimitsd::min())
// return false;
// Now \lambda would read
// lambda = 1/denom*dot(b, d1crossd2);
// To avoid an expensive division we multiply by |denom|
double lambdaDenom = signDenom*dot(b, d1crossd2);
if (lambdaDenom < 0)
return false;
// For line segment we would test against
// if (1 < lambda)
// return false;
// with the original lambda. The multiplied test would read
// if (absDenom < lambdaDenom)
// return false;
double absDenom = fabs(denom);
double absDenomEps = absDenom*eps;
SGVec3d bcrossr = cross(b, dir);
// double mu1 = 1/denom*dot(d2, bcrossr);
double mu1 = signDenom*dot(d2, bcrossr);
if (mu1 < -absDenomEps)
return false;
// double mu2 = -1/denom*dot(d1, bcrossr);
// if (mu2 < -eps)
// return false;
double mmu2 = signDenom*dot(d1, bcrossr);
if (mmu2 > absDenomEps)
return false;
if (mu1 - mmu2 > absDenom + absDenomEps)
return false;
x = point;
// if we have survived here it could only happen with denom == 0
// that the point is already in plane. Then return the origin ...
if (SGLimitsd::min() < absDenom)
x += (lambdaDenom/absDenom)*dir;
return true;
}
static inline bool
fgdPointInTriangle( const SGVec3d& point, const SGVec3d tri[3] )
{
SGVec3d dif;
// Some tolerance in meters we accept a point to be outside of the triangle
// and still return that it is inside.
SGDfloat min, max;
// punt if outside bouding cube
SG_MIN_MAX3 ( min, max, tri[0][0], tri[1][0], tri[2][0] );
if( (point[0] < min) || (point[0] > max) )
return false;
dif[0] = max - min;
SG_MIN_MAX3 ( min, max, tri[0][1], tri[1][1], tri[2][1] );
if( (point[1] < min) || (point[1] > max) )
return false;
dif[1] = max - min;
SG_MIN_MAX3 ( min, max, tri[0][2], tri[1][2], tri[2][2] );
if( (point[2] < min) || (point[2] > max) )
return false;
dif[2] = max - min;
// drop the smallest dimension so we only have to work in 2d.
SGDfloat min_dim = SG_MIN3 (dif[0], dif[1], dif[2]);
SGDfloat x1, y1, x2, y2, x3, y3, rx, ry;
if ( fabs(min_dim-dif[0]) <= DBL_EPSILON ) {
// x is the smallest dimension
x1 = point[1];
y1 = point[2];
x2 = tri[0][1];
y2 = tri[0][2];
x3 = tri[1][1];
y3 = tri[1][2];
rx = tri[2][1];
ry = tri[2][2];
} else if ( fabs(min_dim-dif[1]) <= DBL_EPSILON ) {
// y is the smallest dimension
x1 = point[0];
y1 = point[2];
x2 = tri[0][0];
y2 = tri[0][2];
x3 = tri[1][0];
y3 = tri[1][2];
rx = tri[2][0];
ry = tri[2][2];
} else if ( fabs(min_dim-dif[2]) <= DBL_EPSILON ) {
// z is the smallest dimension
x1 = point[0];
y1 = point[1];
x2 = tri[0][0];
y2 = tri[0][1];
x3 = tri[1][0];
y3 = tri[1][1];
rx = tri[2][0];
ry = tri[2][1];
} else {
// all dimensions are really small so lets call it close
// enough and return a successful match
return true;
}
// check if intersection point is on the same side of p1 <-> p2 as p3
SGDfloat tmp = (y2 - y3);
SGDfloat tmpn = (x2 - x3);
int side1 = SG_SIGN (tmp * (rx - x3) + (y3 - ry) * tmpn);
int side2 = SG_SIGN (tmp * (x1 - x3) + (y3 - y1) * tmpn);
if ( side1 != side2 ) {
// printf("failed side 1 check\n");
return false;
}
// check if intersection point is on correct side of p2 <-> p3 as p1
tmp = (y3 - ry);
tmpn = (x3 - rx);
side1 = SG_SIGN (tmp * (x2 - rx) + (ry - y2) * tmpn);
side2 = SG_SIGN (tmp * (x1 - rx) + (ry - y1) * tmpn);
if ( side1 != side2 ) {
// printf("failed side 2 check\n");
return false;
}
// check if intersection point is on correct side of p1 <-> p3 as p2
tmp = (y2 - ry);
tmpn = (x2 - rx);
side1 = SG_SIGN (tmp * (x3 - rx) + (ry - y3) * tmpn);
side2 = SG_SIGN (tmp * (x1 - rx) + (ry - y1) * tmpn);
if ( side1 != side2 ) {
// printf("failed side 3 check\n");
return false;
}
return true;
}
// Test if the line given by the point on the line pt_on_line and the
// line direction dir intersects the sphere sp.
// Adapted from plib.
static inline bool
fgdIsectSphereInfLine(const SGVec3d& sphereCenter, double radius,
const SGVec3d& pt_on_line, const SGVec3d& dir)
{
SGVec3d r = sphereCenter - pt_on_line;
double projectedDistance = dot(r, dir);
double dist = dot(r, r) - projectedDistance * projectedDistance;
return dist < radius*radius;
}
template<typename T>
class SGExtendedTriangleFunctor : public osg::TriangleFunctor<T> {
public:
// Ok, to be complete we should also implement the indexed variants
// For now this one appears to be enough ...
void drawArrays(GLenum mode, GLint first, GLsizei count)
{
if (_vertexArrayPtr==0 || count==0) return;
const osg::Vec3* vlast;
const osg::Vec3* vptr;
switch(mode) {
case(GL_LINES):
vlast = &_vertexArrayPtr[first+count];
for(vptr=&_vertexArrayPtr[first];vptr<vlast;vptr+=2)
this->operator()(*(vptr),*(vptr+1),_treatVertexDataAsTemporary);
break;
case(GL_LINE_STRIP):
vlast = &_vertexArrayPtr[first+count-1];
for(vptr=&_vertexArrayPtr[first];vptr<vlast;++vptr)
this->operator()(*(vptr),*(vptr+1),_treatVertexDataAsTemporary);
break;
case(GL_LINE_LOOP):
vlast = &_vertexArrayPtr[first+count-1];
for(vptr=&_vertexArrayPtr[first];vptr<vlast;++vptr)
this->operator()(*(vptr),*(vptr+1),_treatVertexDataAsTemporary);
this->operator()(_vertexArrayPtr[first+count-1],
_vertexArrayPtr[first],_treatVertexDataAsTemporary);
break;
default:
osg::TriangleFunctor<T>::drawArrays(mode, first, count);
break;
}
}
protected:
using osg::TriangleFunctor<T>::_vertexArrayPtr;
using osg::TriangleFunctor<T>::_treatVertexDataAsTemporary;
};
class GroundCacheFillVisitor : public osg::NodeVisitor {
public:
/// class to just redirect triangles to the GroundCacheFillVisitor
class GroundCacheFill {
public:
void setGroundCacheFillVisitor(GroundCacheFillVisitor* gcfv)
{ mGroundCacheFillVisitor = gcfv; }
void operator () (const osg::Vec3& v1, const osg::Vec3& v2,
const osg::Vec3& v3, bool)
{ mGroundCacheFillVisitor->addTriangle(v1, v2, v3); }
void operator () (const osg::Vec3& v1, const osg::Vec3& v2, bool)
{ mGroundCacheFillVisitor->addLine(v1, v2); }
private:
GroundCacheFillVisitor* mGroundCacheFillVisitor;
};
GroundCacheFillVisitor(FGGroundCache* groundCache,
const SGVec3d& down,
const SGVec3d& cacheReference,
double cacheRadius,
double wireCacheRadius) :
osg::NodeVisitor(osg::NodeVisitor::TRAVERSE_ACTIVE_CHILDREN),
mGroundCache(groundCache)
{
setTraversalMask(SG_NODEMASK_TERRAIN_BIT);
mDown = down;
mLocalDown = down;
sphIsec = true;
mBackfaceCulling = false;
mCacheReference = cacheReference;
mLocalCacheReference = cacheReference;
mCacheRadius = cacheRadius;
mWireCacheRadius = wireCacheRadius;
mTriangleFunctor.setGroundCacheFillVisitor(this);
mGroundProperty.wire_id = -1;
mGroundProperty.vel = SGVec3d(0, 0, 0);
mGroundProperty.rot = SGVec3d(0, 0, 0);
mGroundProperty.pivot = SGVec3d(0, 0, 0);
}
void updateCullMode(osg::StateSet* stateSet)
{
if (!stateSet)
return;
osg::StateAttribute* stateAttribute;
stateAttribute = stateSet->getAttribute(osg::StateAttribute::CULLFACE);
if (!stateAttribute)
return;
osg::CullFace* cullFace = static_cast<osg::CullFace*>(stateAttribute);
mBackfaceCulling = cullFace->getMode() == osg::CullFace::BACK;
}
bool enterBoundingSphere(const osg::BoundingSphere& bs)
{
if (!bs.valid())
return false;
SGVec3d cntr(osg::Vec3d(bs.center())*mLocalToGlobal);
double rc = bs.radius() + mCacheRadius;
// Ok, this node might intersect the cache. Visit it in depth.
double centerDist2 = distSqr(mCacheReference, cntr);
if (centerDist2 < rc*rc) {
sphIsec = true;
} else {
// Check if the down direction touches the bounding sphere of the node
// if so, do at least croase agl computations.
// Ther other thing is that we must check if we are in range of
// cats or wires
double rw = bs.radius() + mWireCacheRadius;
if (rw*rw < centerDist2 &&
!fgdIsectSphereInfLine(cntr, bs.radius(), mCacheReference, mDown))
return false;
sphIsec = false;
}
return true;
}
bool enterNode(osg::Node& node)
{
if (!enterBoundingSphere(node.getBound()))
return false;
updateCullMode(node.getStateSet());
FGGroundCache::GroundProperty& gp = mGroundProperty;
// get some material information for use in the gear model
gp.material = globals->get_matlib()->findMaterial(&node);
if (gp.material) {
gp.type = gp.material->get_solid() ? FGInterface::Solid : FGInterface::Water;
return true;
}
osg::Referenced* base = node.getUserData();
if (!base)
return true;
FGAICarrierHardware *ud =
dynamic_cast<FGAICarrierHardware*>(base);
if (!ud)
return true;
switch (ud->type) {
case FGAICarrierHardware::Wire:
gp.type = FGInterface::Wire;
gp.wire_id = ud->id;
break;
case FGAICarrierHardware::Catapult:
gp.type = FGInterface::Catapult;
break;
default:
gp.type = FGInterface::Solid;
break;
}
// Copy the velocity from the carrier class.
ud->carrier->getVelocityWrtEarth(gp.vel, gp.rot, gp.pivot);
return true;
}
void fillWith(osg::Drawable* drawable)
{
bool oldSphIsec = sphIsec;
if (!enterBoundingSphere(drawable->getBound()))
return;
bool oldBackfaceCulling = mBackfaceCulling;
updateCullMode(drawable->getStateSet());
drawable->accept(mTriangleFunctor);
mBackfaceCulling = oldBackfaceCulling;
sphIsec = oldSphIsec;
}
virtual void apply(osg::Geode& geode)
{
bool oldBackfaceCulling = mBackfaceCulling;
bool oldSphIsec = sphIsec;
FGGroundCache::GroundProperty oldGp = mGroundProperty;
if (!enterNode(geode))
return;
for(unsigned i = 0; i < geode.getNumDrawables(); ++i)
fillWith(geode.getDrawable(i));
sphIsec = oldSphIsec;
mGroundProperty = oldGp;
mBackfaceCulling = oldBackfaceCulling;
}
virtual void apply(osg::Group& group)
{
bool oldBackfaceCulling = mBackfaceCulling;
bool oldSphIsec = sphIsec;
FGGroundCache::GroundProperty oldGp = mGroundProperty;
if (!enterNode(group))
return;
traverse(group);
sphIsec = oldSphIsec;
mBackfaceCulling = oldBackfaceCulling;
mGroundProperty = oldGp;
}
virtual void apply(osg::Transform& transform)
{
if (!enterNode(transform))
return;
bool oldBackfaceCulling = mBackfaceCulling;
bool oldSphIsec = sphIsec;
FGGroundCache::GroundProperty oldGp = mGroundProperty;
/// transform the caches center to local coords
osg::Matrix oldLocalToGlobal = mLocalToGlobal;
osg::Matrix oldGlobalToLocal = mGlobalToLocal;
transform.computeLocalToWorldMatrix(mLocalToGlobal, this);
transform.computeWorldToLocalMatrix(mGlobalToLocal, this);
SGVec3d oldLocalCacheReference = mLocalCacheReference;
mLocalCacheReference.osg() = mCacheReference.osg()*mGlobalToLocal;
SGVec3d oldLocalDown = mLocalDown;
mLocalDown.osg() = osg::Matrixd::transform3x3(mDown.osg(), mGlobalToLocal);
// walk the children
traverse(transform);
// Restore that one
mLocalDown = oldLocalDown;
mLocalCacheReference = oldLocalCacheReference;
mLocalToGlobal = oldLocalToGlobal;
mGlobalToLocal = oldGlobalToLocal;
sphIsec = oldSphIsec;
mBackfaceCulling = oldBackfaceCulling;
mGroundProperty = oldGp;
}
void addTriangle(const osg::Vec3& v1, const osg::Vec3& v2,
const osg::Vec3& v3)
{
SGVec3d v[3] = {
SGVec3d(v1),
SGVec3d(v2),
SGVec3d(v3)
};
// a bounding sphere in the node local system
SGVec3d boundCenter = (1.0/3)*(v[0] + v[1] + v[2]);
#if 0
double boundRadius = std::max(norm1(v[0] - boundCenter),
norm1(v[1] - boundCenter));
boundRadius = std::max(boundRadius, norm1(v[2] - boundCenter));
// Ok, we take the 1-norm instead of the expensive 2 norm.
// Therefore we need that scaling factor - roughly sqrt(3)
boundRadius = 1.733*boundRadius;
#else
double boundRadius = std::max(distSqr(v[0], boundCenter),
distSqr(v[1], boundCenter));
boundRadius = std::max(boundRadius, distSqr(v[2], boundCenter));
boundRadius = sqrt(boundRadius);
#endif
// if we are not in the downward cylinder bail out
if (!fgdIsectSphereInfLine(boundCenter, boundRadius + mCacheRadius,
mLocalCacheReference, mLocalDown))
return;
// The normal and plane in the node local coordinate system
SGVec3d n = normalize(cross(v[1] - v[0], v[2] - v[0]));
if (0 < dot(mLocalDown, n)) {
if (mBackfaceCulling) {
// Surface points downwards, ignore for altitude computations.
return;
} else {
n = -n;
std::swap(v[1], v[2]);
}
}
// Only check if the triangle is in the cache sphere if the plane
// containing the triangle is near enough
if (sphIsec && fabs(dot(n, v[0] - mLocalCacheReference)) < mCacheRadius) {
// Check if the sphere around the vehicle intersects the sphere
// around that triangle. If so, put that triangle into the cache.
double r2 = boundRadius + mCacheRadius;
if (distSqr(boundCenter, mLocalCacheReference) < r2*r2) {
FGGroundCache::Triangle t;
for (unsigned i = 0; i < 3; ++i)
t.vertices[i].osg() = v[i].osg()*mLocalToGlobal;
t.boundCenter.osg() = boundCenter.osg()*mLocalToGlobal;
t.boundRadius = boundRadius;
SGVec3d tmp;
tmp.osg() = osg::Matrixd::transform3x3(n.osg(), mLocalToGlobal);
t.plane = SGVec4d(tmp[0], tmp[1], tmp[2], -dot(tmp, t.vertices[0]));
t.velocity = mGroundProperty.vel;
t.rotation = mGroundProperty.rot;
t.rotation_pivot = mGroundProperty.pivot - mGroundCache->cache_center;
t.type = mGroundProperty.type;
mGroundCache->triangles.push_back(t);
}
}
// In case the cache is empty, we still provide agl computations.
// But then we use the old way of having a fixed elevation value for
// the whole lifetime of this cache.
SGVec4d plane = SGVec4d(n[0], n[1], n[2], -dot(n, v[0]));
SGVec3d isectpoint;
if (fgdRayTriangle(isectpoint, mLocalCacheReference, mLocalDown, v)) {
mGroundCache->found_ground = true;
isectpoint.osg() = isectpoint.osg()*mLocalToGlobal;
isectpoint += mGroundCache->cache_center;
double this_radius = length(isectpoint);
if (mGroundCache->ground_radius < this_radius)
mGroundCache->ground_radius = this_radius;
}
}
void addLine(const osg::Vec3& v1, const osg::Vec3& v2)
{
SGVec3d gv1(osg::Vec3d(v1)*mLocalToGlobal);
SGVec3d gv2(osg::Vec3d(v2)*mLocalToGlobal);
SGVec3d boundCenter = 0.5*(gv1 + gv2);
double boundRadius = length(gv1 - boundCenter);
if (distSqr(boundCenter, mCacheReference)
< (boundRadius + mWireCacheRadius)*(boundRadius + mWireCacheRadius) ) {
if (mGroundProperty.type == FGInterface::Wire) {
FGGroundCache::Wire wire;
wire.ends[0] = gv1;
wire.ends[1] = gv2;
wire.velocity = mGroundProperty.vel;
wire.rotation = mGroundProperty.rot;
wire.rotation_pivot = mGroundProperty.pivot - mGroundCache->cache_center;
wire.wire_id = mGroundProperty.wire_id;
mGroundCache->wires.push_back(wire);
}
if (mGroundProperty.type == FGInterface::Catapult) {
FGGroundCache::Catapult cat;
// Trick to get the ends in the right order.
// Use the x axis in the original coordinate system. Choose the
// most negative x-axis as the one pointing forward
if (v1[0] < v2[0]) {
cat.start = gv1;
cat.end = gv2;
} else {
cat.start = gv2;
cat.end = gv1;
}
cat.velocity = mGroundProperty.vel;
cat.rotation = mGroundProperty.rot;
cat.rotation_pivot = mGroundProperty.pivot - mGroundCache->cache_center;
mGroundCache->catapults.push_back(cat);
}
}
}
SGExtendedTriangleFunctor<GroundCacheFill> mTriangleFunctor;
FGGroundCache* mGroundCache;
SGVec3d mCacheReference;
double mCacheRadius;
double mWireCacheRadius;
osg::Matrix mLocalToGlobal;
osg::Matrix mGlobalToLocal;
SGVec3d mDown;
SGVec3d mLocalDown;
SGVec3d mLocalCacheReference;
bool sphIsec;
bool mBackfaceCulling;
FGGroundCache::GroundProperty mGroundProperty;
};
FGGroundCache::FGGroundCache()
{
cache_center = SGVec3d(0, 0, 0);
ground_radius = 0.0;
cache_ref_time = 0.0;
wire_id = 0;
reference_wgs84_point = SGVec3d(0, 0, 0);
reference_vehicle_radius = 0.0;
found_ground = false;
}
FGGroundCache::~FGGroundCache()
{
}
inline void
FGGroundCache::velocityTransformTriangle(double dt,
FGGroundCache::Triangle& dst,
const FGGroundCache::Triangle& src)
{
dst = src;
if (fabs(dt*dot(src.velocity, src.velocity)) < SGLimitsd::epsilon())
return;
for (int i = 0; i < 3; ++i) {
SGVec3d pivotoff = src.vertices[i] - src.rotation_pivot;
dst.vertices[i] += dt*(src.velocity + cross(src.rotation, pivotoff));
}
// Transform the plane equation
SGVec3d pivotoff, vel;
sgdSubVec3(pivotoff.sg(), dst.plane.sg(), src.rotation_pivot.sg());
vel = src.velocity + cross(src.rotation, pivotoff);
dst.plane[3] += dt*sgdScalarProductVec3(dst.plane.sg(), vel.sg());
dst.boundCenter += dt*src.velocity;
}
bool
FGGroundCache::prepare_ground_cache(double ref_time, const SGVec3d& pt,
double rad)
{
// Empty cache.
ground_radius = 0.0;
found_ground = false;
triangles.resize(0);
catapults.resize(0);
wires.resize(0);
// Store the parameters we used to build up that cache.
reference_wgs84_point = pt;
reference_vehicle_radius = rad;
// Store the time reference used to compute movements of moving triangles.
cache_ref_time = ref_time;
// Get a normalized down vector valid for the whole cache
SGQuatd hlToEc = SGQuatd::fromLonLat(SGGeod::fromCart(pt));
down = hlToEc.rotate(SGVec3d(0, 0, 1));
// Decide where we put the scenery center.
SGVec3d old_cntr = globals->get_scenery()->get_center();
SGVec3d cntr(pt);
// Only move the cache center if it is unacceptable far away.
if (40*40 < distSqr(old_cntr, cntr))
globals->get_scenery()->set_center(cntr);
else
cntr = old_cntr;
// The center of the cache.
cache_center = cntr;
// Prepare sphere around the aircraft.
SGVec3d ptoff = pt - cache_center;
double cacheRadius = rad;
// Prepare bigger sphere around the aircraft.
// This one is required for reliably finding wires we have caught but
// have already left the hopefully smaller sphere for the ground reactions.
const double max_wire_dist = 300.0;
double wireCacheRadius = max_wire_dist < rad ? rad : max_wire_dist;
// Walk the scene graph and extract solid ground triangles and carrier data.
GroundCacheFillVisitor gcfv(this, down, ptoff, cacheRadius, wireCacheRadius);
globals->get_scenery()->get_scene_graph()->accept(gcfv);
// some stats
SG_LOG(SG_FLIGHT,SG_DEBUG, "prepare_ground_cache(): ac radius = " << rad
<< ", # triangles = " << triangles.size()
<< ", # wires = " << wires.size()
<< ", # catapults = " << catapults.size()
<< ", ground_radius = " << ground_radius );
// If the ground radius is still below 5e6 meters, then we do not yet have
// any scenery.
found_ground = found_ground && 5e6 < ground_radius;
if (!found_ground)
SG_LOG(SG_FLIGHT, SG_WARN, "prepare_ground_cache(): trying to build cache "
"without any scenery below the aircraft" );
if (cntr != old_cntr)
globals->get_scenery()->set_center(old_cntr);
return found_ground;
}
bool
FGGroundCache::is_valid(double& ref_time, SGVec3d& pt, double& rad)
{
pt = reference_wgs84_point;
rad = reference_vehicle_radius;
ref_time = cache_ref_time;
return found_ground;
}
double
FGGroundCache::get_cat(double t, const SGVec3d& dpt,
SGVec3d end[2], SGVec3d vel[2])
{
// start with a distance of 1e10 meters...
double dist = 1e10;
// Time difference to the reference time.
t -= cache_ref_time;
size_t sz = catapults.size();
for (size_t i = 0; i < sz; ++i) {
SGVec3d pivotoff, rvel[2];
pivotoff = catapults[i].start - catapults[i].rotation_pivot;
rvel[0] = catapults[i].velocity + cross(catapults[i].rotation, pivotoff);
pivotoff = catapults[i].end - catapults[i].rotation_pivot;
rvel[1] = catapults[i].velocity + cross(catapults[i].rotation, pivotoff);
SGVec3d thisEnd[2];
thisEnd[0] = cache_center + catapults[i].start + t*rvel[0];
thisEnd[1] = cache_center + catapults[i].end + t*rvel[1];
sgdLineSegment3 ls;
sgdCopyVec3(ls.a, thisEnd[0].sg());
sgdCopyVec3(ls.b, thisEnd[1].sg());
double this_dist = sgdDistSquaredToLineSegmentVec3( ls, dpt.sg() );
if (this_dist < dist) {
SG_LOG(SG_FLIGHT,SG_INFO, "Found catapult "
<< this_dist << " meters away");
dist = this_dist;
end[0] = thisEnd[0];
end[1] = thisEnd[1];
vel[0] = rvel[0];
vel[1] = rvel[1];
}
}
// At the end take the root, we only computed squared distances ...
return sqrt(dist);
}
bool
FGGroundCache::get_agl(double t, const SGVec3d& dpt, double max_altoff,
SGVec3d& contact, SGVec3d& normal, SGVec3d& vel,
int *type, const SGMaterial** material, double *agl)
{
bool ret = false;
*type = FGInterface::Unknown;
// *agl = 0.0;
if (material)
*material = 0;
vel = SGVec3d(0, 0, 0);
contact = SGVec3d(0, 0, 0);
normal = SGVec3d(0, 0, 0);
// Time difference to th reference time.
t -= cache_ref_time;
// The double valued point we start to search for intersection.
SGVec3d pt = dpt - cache_center;
// shift the start of our ray by maxaltoff upwards
SGVec3d raystart = pt - max_altoff*down;
// Initialize to something sensible
double current_radius = 0.0;
size_t sz = triangles.size();
for (size_t i = 0; i < sz; ++i) {
Triangle triangle;
velocityTransformTriangle(t, triangle, triangles[i]);
if (!fgdIsectSphereInfLine(triangle.boundCenter, triangle.boundRadius, pt, down))
continue;
// Check for intersection.
SGVec3d isecpoint;
if (fgdRayTriangle(isecpoint, raystart, down, triangle.vertices)) {
// Compute the vector from pt to the intersection point ...
SGVec3d off = isecpoint - pt;
// ... and check if it is too high or not
// Transform to the wgs system
isecpoint += cache_center;
// compute the radius, good enough approximation to take the geocentric radius
double radius = dot(isecpoint, isecpoint);
if (current_radius < radius) {
current_radius = radius;
ret = true;
// Save the new potential intersection point.
contact = isecpoint;
// The first three values in the vector are the plane normal.
sgdCopyVec3( normal.sg(), triangle.plane.sg() );
// The velocity wrt earth.
SGVec3d pivotoff = pt - triangle.rotation_pivot;
vel = triangle.velocity + cross(triangle.rotation, pivotoff);
// Save the ground type.
*type = triangle.type;
*agl = dot(down, contact - dpt);
if (material)
*material = triangle.material;
}
}
}
if (ret)
return true;
// Whenever we did not have a ground triangle for the requested point,
// take the ground level we found during the current cache build.
// This is as good as what we had before for agl.
double r = length(dpt);
contact = dpt;
contact *= ground_radius/r;
normal = -down;
vel = SGVec3d(0, 0, 0);
// The altitude is the distance of the requested point from the
// contact point.
*agl = dot(down, contact - dpt);
*type = FGInterface::Unknown;
return ret;
}
bool FGGroundCache::caught_wire(double t, const SGVec3d pt[4])
{
size_t sz = wires.size();
if (sz == 0)
return false;
// Time difference to the reference time.
t -= cache_ref_time;
// Build the two triangles spanning the area where the hook has moved
// during the past step.
SGVec4d plane[2];
SGVec3d tri[2][3];
sgdMakePlane( plane[0].sg(), pt[0].sg(), pt[1].sg(), pt[2].sg() );
tri[0][0] = pt[0];
tri[0][1] = pt[1];
tri[0][2] = pt[2];
sgdMakePlane( plane[1].sg(), pt[0].sg(), pt[2].sg(), pt[3].sg() );
tri[1][0] = pt[0];
tri[1][1] = pt[2];
tri[1][2] = pt[3];
// Intersect the wire lines with each of these triangles.
// You have caught a wire if they intersect.
for (size_t i = 0; i < sz; ++i) {
SGVec3d le[2];
for (int k = 0; k < 2; ++k) {
le[k] = wires[i].ends[k];
SGVec3d pivotoff = le[k] - wires[i].rotation_pivot;
SGVec3d vel = wires[i].velocity + cross(wires[i].rotation, pivotoff);
le[k] += t*vel + cache_center;
}
for (int k=0; k<2; ++k) {
SGVec3d isecpoint;
double isecval = sgdIsectLinesegPlane(isecpoint.sg(), le[0].sg(),
le[1].sg(), plane[k].sg());
if ( 0.0 <= isecval && isecval <= 1.0 &&
fgdPointInTriangle( isecpoint, tri[k] ) ) {
SG_LOG(SG_FLIGHT,SG_INFO, "Caught wire");
// Store the wire id.
wire_id = wires[i].wire_id;
return true;
}
}
}
return false;
}
bool FGGroundCache::get_wire_ends(double t, SGVec3d end[2], SGVec3d vel[2])
{
// Fast return if we do not have an active wire.
if (wire_id < 0)
return false;
// Time difference to the reference time.
t -= cache_ref_time;
// Search for the wire with the matching wire id.
size_t sz = wires.size();
for (size_t i = 0; i < sz; ++i) {
if (wires[i].wire_id == wire_id) {
for (size_t k = 0; k < 2; ++k) {
SGVec3d pivotoff = end[k] - wires[i].rotation_pivot;
vel[k] = wires[i].velocity + cross(wires[i].rotation, pivotoff);
end[k] = cache_center + wires[i].ends[k] + t*vel[k];
}
return true;
}
}
return false;
}
void FGGroundCache::release_wire(void)
{
wire_id = -1;
}
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