Bullet's understanding of force Torque Impulse

Before you learn about Force Impulse Torque , take a look at setlinearvelocity,setangularvelocity

One is the line speed, one is the angular velocity.

It's easy to understand. Set the body's line speed and angular velocity

Line Speed Const BTVECTOR3 & getlinearvelocity () constvoid setlinearvelocity (const BTVECTOR3 &lin_vel)//angular Speed const BtV Ector3 & Getangularvelocity () constvoid setangularvelocity (const BTVECTOR3 &ang_vel)

Now to understand force

void Applycentralforce (const BTVECTOR3 &force) void Applyforce (const BTVECTOR3 &force, const BTVECTOR3 &REL_ Pos

Applycentralforce provides a force to the body to view the source code

void Applycentralforce (const btvector3& force) {<span style= "white-space:pre" ></span>m_totalforce + = Force*m_linearfactor;}

On the basis of the original force of the body and add Force *m_linearfactor , as for this m_ Linearfactor

void Setlinearfactor (const btvector3& linearfactor) {m_linearfactor = Linearfactor;m_invmass = M_linearFactor*m_ Inversemass;}

is to apply the force of the three direction of scaling a certain multiples.

The Applyforce also provides a force to the body,

Voidapplyforce (const btvector3& Force, const btvector3& Rel_pos) {applycentralforce (force);// First, the Force Applytorque (Rel_pos.cross (Force*m_linearfactor)) is applied directly;//Then the torsion force is applied}

The cross-multiplication of the vectors gets another vector perpendicular to the two vectors.

Rel_pos . Cross (Force*m_linearfactor) can get Torsion Force

Suppose force = (0, 0, -10), Rel_pos = (0, 1, 0),

Force * Rel_pos = (-10, 0, 0) to get torsional forces around the x-axis

Remember Applyforce not exerting force alone

Now look at torque.

The previous applyforce has been mentioned, providing a torsion force

Voidapplytorque (const btvector3& torque) {m_totaltorque + = Torque*m_angularfactor;}

Suppose torque = (10, 5,-10)

is to rotate around the torque.normalize axis.

Now to understand Impulse

void Applycentralimpulse (const btvector3& Impulse) {m_linearvelocity + = Impulse *m_linearfactor * M_INVERSEMASS;} void Applytorqueimpulse (const btvector3& torque) {m_angularvelocity + = M_invinertiatensorworld * Torque * m_ Angularfactor;} void Applyimpulse (const btvector3& Impulse, const btvector3& rel_pos) {if (M_inversemass! = btscalar (0.)) {Applycentralimpulse (Impulse), if (m_angularfactor) {Applytorqueimpulse (Rel_pos.cross (Impulse*m_linearfactor));}}}

All the impulse are listed, the introduction of the impulse can be seen in the encyclopedia.

If you want to use it, simply understand the inverse of impulse * quality = increased speed (line speed or angular velocity)

look at the source code will know Applycentralimpulse , Applyimpulse Just follow Applycenterforce and Applyforce almost

If force is to be used to move the body around every frame, the impulse is instantaneous to provide a speed that is only applied when needed

For Set****factor only used when apply***, and set***velocity not used.

void Clearforces ()

The force and torque are removed, but the body is still affected by gravity.

_ballbody->setactivationstate (active_tag);

Of course, when exerting a force, to set the body state to active, only the active object can be simulated, which is also an aspect of optimization.

No source code, no examples, just simple understanding, a lot less, just for learning.

Bullet's understanding of force Torque Impulse