From 764eb2a2e77bdf699f99e5e25ad0d9026efc0927 Mon Sep 17 00:00:00 2001
From: andy <andy>
Date: Wed, 20 Feb 2002 07:12:27 +0000
Subject: [PATCH] Automatically generate "contact" points for collision
detection. Implemented as extra (and invisible) gear objects.
---
src/FDM/YASim/Airplane.cpp | 61 ++++++++++++++++++++++++++++++++++++++
src/FDM/YASim/Airplane.hpp | 3 ++
src/FDM/YASim/Wing.cpp | 15 ++++++++++
src/FDM/YASim/Wing.hpp | 4 +++
4 files changed, 83 insertions(+)
diff --git a/src/FDM/YASim/Airplane.cpp b/src/FDM/YASim/Airplane.cpp
index da81beba2..7515dc639 100644
--- a/src/FDM/YASim/Airplane.cpp
+++ b/src/FDM/YASim/Airplane.cpp
@@ -46,6 +46,8 @@ Airplane::~Airplane()
delete (GearRec*)_gears.get(i);
for(i=0; i<_surfs.size(); i++)
delete (Surface*)_surfs.get(i);
+ for(i=0; i<_contacts.size(); i++)
+ delete[] (float*)_contacts.get(i);
}
void Airplane::iterate(float dt)
@@ -350,8 +352,26 @@ void Airplane::setupState(float aoa, float speed, State* s)
s->pos[2] = 1;
}
+void Airplane::addContactPoint(float* pos)
+{
+ float* cp = new float[3];
+ cp[0] = pos[0];
+ cp[1] = pos[1];
+ cp[2] = pos[2];
+ _contacts.add(cp);
+}
+
float Airplane::compileWing(Wing* w)
{
+ // The tip of the wing is a contact point
+ float tip[3];
+ w->getTip(tip);
+ addContactPoint(tip);
+ if(w->isMirrored()) {
+ tip[1] *= -1;
+ addContactPoint(tip);
+ }
+
// Make sure it's initialized. The surfaces will pop out with
// total drag coefficients equal to their areas, which is what we
// want.
@@ -379,6 +399,10 @@ float Airplane::compileWing(Wing* w)
float Airplane::compileFuselage(Fuselage* f)
{
+ // The front and back are contact points
+ addContactPoint(f->front);
+ addContactPoint(f->back);
+
float wgt = 0;
float fwd[3];
Math::sub3(f->front, f->back, fwd);
@@ -456,6 +480,39 @@ void Airplane::compileGear(GearRec* gr)
_surfs.add(s);
}
+void Airplane::compileContactPoints()
+{
+ // Figure it will compress by 20cm
+ float comp[3];
+ float DIST = 0.2;
+ comp[0] = 0; comp[1] = 0; comp[2] = DIST;
+
+ // Give it a spring constant such that at full compression it will
+ // hold up 10 times the planes mass. That's about right. Yeah.
+ float mass = _model.getBody()->getTotalMass();
+ float spring = (1/DIST) * 9.8 * 10 * mass;
+ float damp = 2 * Math::sqrt(spring * mass);
+
+ int i;
+ for(i=0; i<_contacts.size(); i++) {
+ float *cp = (float*)_contacts.get(i);
+
+ Gear* g = new Gear();
+ g->setPosition(cp);
+
+ g->setCompression(comp);
+ g->setSpring(spring);
+ g->setDamping(damp);
+ g->setBrake(1);
+
+ // I made these up
+ g->setStaticFriction(0.6);
+ g->setDynamicFriction(0.5);
+
+ _model.addGear(g);
+ }
+}
+
void Airplane::compile()
{
double ground[3];
@@ -529,6 +586,10 @@ void Airplane::compile()
solveGear();
solve();
+ // Do this after solveGear, because it creates "gear" objects that
+ // we don't want to affect.
+ compileContactPoints();
+
// Drop the gear (use a really big dt)
setGearState(true, 1000000);
}
diff --git a/src/FDM/YASim/Airplane.hpp b/src/FDM/YASim/Airplane.hpp
index de0038b63..e1901af76 100644
--- a/src/FDM/YASim/Airplane.hpp
+++ b/src/FDM/YASim/Airplane.hpp
@@ -90,6 +90,8 @@ private:
void applyDragFactor(float factor);
void applyLiftRatio(float factor);
float clamp(float val, float min, float max);
+ void addContactPoint(float* pos);
+ void compileContactPoints();
float normFactor(float f);
Model _model;
@@ -108,6 +110,7 @@ private:
float _ballast;
Vector _gears;
+ Vector _contacts; // non-gear ground contact points
Vector _weights;
Vector _surfs; // NON-wing Surfaces
diff --git a/src/FDM/YASim/Wing.cpp b/src/FDM/YASim/Wing.cpp
index 22cc84a66..bd8ecb979 100644
--- a/src/FDM/YASim/Wing.cpp
+++ b/src/FDM/YASim/Wing.cpp
@@ -208,6 +208,21 @@ float Wing::getGroundEffect(float* posOut)
return span;
}
+void Wing::getTip(float* tip)
+{
+ tip[0] = -Math::tan(_sweep);
+ tip[1] = Math::cos(_dihedral);
+ tip[2] = Math::sin(_dihedral);
+ Math::unit3(tip, tip);
+ Math::mul3(_length, tip, tip);
+ Math::add3(_base, tip, tip);
+}
+
+bool Wing::isMirrored()
+{
+ return _mirror;
+}
+
void Wing::compile()
{
// Have we already been compiled?
diff --git a/src/FDM/YASim/Wing.hpp b/src/FDM/YASim/Wing.hpp
index 861436e8a..f6353ddc9 100644
--- a/src/FDM/YASim/Wing.hpp
+++ b/src/FDM/YASim/Wing.hpp
@@ -44,6 +44,10 @@ public:
// Compile the thing into a bunch of Surface objects
void compile();
+ void getTip(float* tip);
+
+ bool isMirrored();
+
// Ground effect information
float getGroundEffect(float* posOut);