Revision: 1373
http://rigsofrods.svn.sourceforge.net/rigsofrods/?rev=1373&view=rev
Author: estamato
Date: 2010-05-05 21:04:47 +0000 (Wed, 05 May 2010)
Log Message:
-----------
Improved static friction patch + bug fix for a case where transition from
static to dynamic friction created abnormally large forces
Modified Paths:
--------------
trunk/source/main/collisions.cpp
Modified: trunk/source/main/collisions.cpp
===================================================================
--- trunk/source/main/collisions.cpp 2010-05-05 20:49:13 UTC (rev 1372)
+++ trunk/source/main/collisions.cpp 2010-05-05 21:04:47 UTC (rev 1373)
@@ -1217,103 +1217,109 @@
{
//normal velocity
- float Vnormal=velocity.dotProduct(normal);
+ float Vnormal = velocity.dotProduct(normal);
// if we are inside the fluid (solid ground is below us)
- if (gm->solid_ground_level!=0.0f && penetration>=0)
+ if (gm->solid_ground_level != 0.0f && penetration >= 0)
{
- if (nso) *nso=0.0f;
+ if (nso) *nso = 0.0f;
- float Vsquared=velocity.squaredLength();
+ float Vsquared = velocity.squaredLength();
// First of all calculate power law fluid viscosity
- float m = gm->flow_consistency_index*approx_pow(Vsquared,
(gm->flow_behavior_index-1.0f)*0.5f);
+ float m = gm->flow_consistency_index * approx_pow(Vsquared,
(gm->flow_behavior_index - 1.0f)*0.5f);
//Then calculate drag based on above. We'are using a simplified
Stokes' drag.
// Per node fluid drag surface coefficient set by node property
applies here
- Vector3 Fdrag=velocity*(-m * node->surface_coef);
+ Vector3 Fdrag = velocity * (-m * node->surface_coef);
//If we have anisotropic drag
- if (gm->drag_anisotropy<1.0f && Vnormal>0)
+ if (gm->drag_anisotropy < 1.0f && Vnormal > 0)
{
float da_factor;
- if (Vsquared>gm->va*gm->va)
- da_factor=1.0;
+ if (Vsquared > gm->va * gm->va)
+ da_factor = 1.0;
else
- da_factor=Vsquared/(gm->va*gm->va);
-
Fdrag+=(Vnormal*m*(1.0f-gm->drag_anisotropy)*da_factor)*normal;
+ da_factor = Vsquared / (gm->va * gm->va);
+ Fdrag += (Vnormal * m * (1.0f - gm->drag_anisotropy) *
da_factor) * normal;
}
- force+=Fdrag;
+ force += Fdrag;
//Now calculate upwards force based on a simplified boyancy
equation;
//If the fluid is pseudoplastic then boyancy is constrained to
only "stopping" a node from going downwards
//Buoyancy per node volume coefficient set by node property
applies here
float Fboyancy = gm->fluid_density * penetration *
(-DEFAULT_GRAVITY) * node->volume_coef;
- if (gm->flow_behavior_index<1.0f && Vnormal>=0.0f)
+ if (gm->flow_behavior_index < 1.0f && Vnormal >= 0.0f)
{
- float Fnormal=force.dotProduct(normal);
- if (Fnormal<0 && Fboyancy>-Fnormal)
+ float Fnormal = force.dotProduct(normal);
+ if (Fnormal < 0 && Fboyancy>-Fnormal)
{
- Fboyancy=-Fnormal;
+ Fboyancy = -Fnormal;
}
}
- force+=Fboyancy*normal;
+ force += Fboyancy*normal;
}
// if we are inside or touching the solid ground
- if (penetration>=gm->solid_ground_level)
+ if (penetration >= gm->solid_ground_level)
{
- Vector3 slip=velocity-Vnormal*normal;
- float slipv=slip.squaredLength();
+ Vector3 slip = velocity - Vnormal*normal;
+ float slipv = slip.squaredLength();
if (fabs(slipv) > 1e-08f)
{
- float invslipv=fast_invSqrt(slipv);
- slip=slip*invslipv;
- slipv=slipv*invslipv;
+ float invslipv = fast_invSqrt(slipv);
+ slip = slip*invslipv;
+ slipv = slipv*invslipv;
}
else
{
- slipv=sqrt(slipv);
+ slipv = sqrt(slipv);
}
- if (nso && gm->solid_ground_level==0.0f) *nso=slipv;
+ if (nso && gm->solid_ground_level == 0.0f) *nso = slipv;
- float Fnormal;
+ float Fnormal = 0.0f;
+ float Fdnormal = 0.0f;
float Freaction;
float Greaction;
+ Fnormal = force.dotProduct(normal);
+ Fdnormal = Fnormal;
+
//steady force
- if (reaction<0)
+ if (reaction < 0)
{
- Fnormal=force.dotProduct(normal);
- Freaction=-Fnormal;
+ Freaction = -Fnormal;
//impact force
- if (Vnormal<0)
+ if (Vnormal < 0)
{
- Freaction+=-Vnormal*node->mass/dt; //Newton's
second law
+ Freaction += -Vnormal * node->mass / dt;
//Newton's second law
}
- if (Freaction<0) Freaction=0.0f;
- } else {
- Freaction=reaction;
- Fnormal=0.0f;
+ if (Freaction < 0) Freaction = 0.0f;
}
+ else
+ {
+ Freaction = reaction;
+ Fnormal = 0.0f;
+ }
float ff;
// If the velocity that we slip is lower than adhesion velocity
and
// we have a downforce and the slip forces are lower than
static friction
// forces then it's time to go into static friction physics
mode.
// This code is a direct translation of textbook static
friction physics
- Greaction=(Freaction * gm->strength * node->friction_coef);
//General moderated reaction, node property sets friction_coef as a
pernodefriction setting
- if ( slipv<(gm->va) && Greaction>0 &&
fabs(force.dotProduct(slip))<=fabs((gm->ms)*Greaction))
+ Greaction = (Freaction * gm->strength * node->friction_coef);
//General moderated reaction, node property sets friction_coef as a
pernodefriction setting
+ float msGreaction = (gm->ms) * Greaction;
+ if (slipv < (gm->va) && Greaction > 0.0f && (force - Fdnormal *
normal).squaredLength() <= msGreaction * msGreaction)
{
// Static friction model (with a little smoothing to
help the integrator deal with it)
-
ff=-(gm->ms)*(1-approx_exp(-fabs(slipv/gm->va)))*Greaction;
- force=(Fnormal+Freaction)*normal + ff*slip;
+ ff = -msGreaction * (1.0f - approx_exp(-slipv /
gm->va));
+ force = (Fnormal + Freaction) * normal + ff*slip;
}
else
{
//Stribek model. It also comes directly from textbooks.
- float
g=gm->mc+(gm->ms-gm->mc)*approx_exp(-approx_pow(slipv/gm->vs, gm->alpha));
- ff=-(g+gm->t2*slipv)*Greaction;
- force+=Freaction*normal + ff*slip;
+ float g = gm->mc + (gm->ms - gm->mc) * min(1.0f,
approx_exp(-approx_pow(slipv / gm->vs, gm->alpha)));
+ ff = -(g + gm->t2 * slipv) * Greaction;
+ force += Freaction * normal + ff*slip;
}
}
}
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