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Use height data to cushion only close to the ground and adjust impulse strength

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This commit is contained in:
Alayan 2018-09-18 20:01:59 +02:00
parent 6af07fac77
commit 6145aff895
2 changed files with 47 additions and 8 deletions
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44
src/physics/btKart.cpp
View File

@ -51,6 +51,12 @@ btKart::btKart(btRigidBody* chassis, btVehicleRaycaster* raycaster,
Kart *kart)
: m_vehicleRaycaster(raycaster)
{
btScalar height = 0;
for (int i=0;i<stk_config->time2Ticks(HISTORY_TIME);i++)
{
m_ground_height.push_back(height);
}
m_chassisBody = chassis;
m_indexRightAxis = 0;
m_indexUpAxis = 1;
@ -121,6 +127,10 @@ void btKart::reset()
wheel.m_raycastInfo.m_suspensionLength = 0;
updateWheelTransform(i, true);
}
for (int i=0;i<stk_config->time2Ticks(HISTORY_TIME);i++)
{
m_ground_height[i] = 0;
}
m_visual_wheels_touch_ground = false;
m_allow_sliding = false;
m_num_wheels_on_ground = 0;
@ -131,6 +141,7 @@ void btKart::reset()
m_max_speed = -1.0f;
m_min_speed = 0.0f;
m_cushioning_disable_time = 0;
m_new_ground_height = 999.9f;
// Set the brakes so that karts don't slide downhill
setAllBrakes(5.0f);
@ -278,10 +289,10 @@ btScalar btKart::rayCast(unsigned int index, float fraction)
btScalar max_susp_len = wheel.getSuspensionRestLength()
+ wheel.m_maxSuspensionTravel;
// Do a slightly longer raycast to see if the kart might soon hit the
// Do a longer raycast to see if the kart might soon hit the
// ground and some 'cushioning' is needed to avoid that the chassis
// hits the ground.
btScalar raylen = max_susp_len + 0.5f;
btScalar raylen = max_susp_len*10 + 0.5f;
btVector3 rayvector = wheel.m_raycastInfo.m_wheelDirectionWS * (raylen);
const btVector3& source = wheel.m_raycastInfo.m_hardPointWS;
@ -297,6 +308,9 @@ btScalar btKart::rayCast(unsigned int index, float fraction)
wheel.m_raycastInfo.m_groundObject = 0;
btScalar depth = raylen * rayResults.m_distFraction;
if (depth < m_new_ground_height)
m_new_ground_height = depth;
if (object && depth < max_susp_len)
{
wheel.m_raycastInfo.m_contactNormalWS = rayResults.m_hitNormalInWorld;
@ -518,6 +532,7 @@ void btKart::updateVehicle( btScalar step )
if(m_cushioning_disable_time>0) m_cushioning_disable_time --;
bool needed_cushioning = false;
btVector3 v =
m_chassisBody->getVelocityInLocalPoint(m_wheelInfo[wheel_index]
.m_chassisConnectionPointCS);
@ -528,7 +543,7 @@ void btKart::updateVehicle( btScalar step )
#ifdef DEBUG_CUSHIONING
Log::verbose("physics",
"World %d wheel %d lsuspl %f vdown %f overall speed %f lenght %f",
"World %d wheel %d lsuspl %f vdown %f overall speed %f length %f",
World::getWorld()->getTimeTicks(),
wheel_index,
m_wheelInfo[wheel_index].m_raycastInfo.m_suspensionLength,
@ -536,6 +551,14 @@ void btKart::updateVehicle( btScalar step )
-v_down.getY() + 9.8*step,
step * (-v_down.getY() + 9.8*step)+offset);
#endif
// Update the ground height history
for (int i=stk_config->time2Ticks(HISTORY_TIME)-1;i>0;i--)
{
m_ground_height[i] = m_ground_height[i-1];
}
m_ground_height[0] = m_new_ground_height;
m_new_ground_height = 999.9f;
// If the kart is falling, estimate the distance the kart will fall
// in the next time step: the speed gets increased by the gravity*dt.
// This approximation is still not good enough (either because of
@ -544,9 +567,15 @@ void btKart::updateVehicle( btScalar step )
// predict the upcoming collision correcty - so we add an offset
// to the predicted kart movement, which was found experimentally:
btScalar gravity = m_chassisBody->getGravity().length();
btScalar predicted_fall = -v_down.getY() + gravity*step +
(m_ground_height[stk_config->time2Ticks(HISTORY_TIME)-1]
-m_ground_height[0])/stk_config->time2Ticks(HISTORY_TIME);
if (v_down.getY()<0 && m_cushioning_disable_time==0 &&
m_wheelInfo[wheel_index].m_raycastInfo.m_suspensionLength
< step * (-v_down.getY()+gravity*step)+offset)
m_ground_height[0] < step*predicted_fall + offset &&
m_ground_height[0] > 0 &&
m_ground_height[stk_config->time2Ticks(HISTORY_TIME)-1] > 0.6)
{
// Disable more cushioning for 1 second. This avoids the problem
// of hovering: a kart gets cushioned on a down-sloping area, still
@ -555,7 +584,7 @@ void btKart::updateVehicle( btScalar step )
m_cushioning_disable_time = stk_config->time2Ticks(1);
needed_cushioning = true;
btVector3 impulse = down * (-v_down.getY() + gravity*step)
btVector3 impulse = down * predicted_fall
/ m_chassisBody->getInvMass();
#ifdef DEBUG_CUSHIONING
float v_old = m_chassisBody->getLinearVelocity().getY();
@ -564,12 +593,13 @@ void btKart::updateVehicle( btScalar step )
#ifdef DEBUG_CUSHIONING
Log::verbose("physics",
"World %d Cushioning imp %f vdown %f from %f m/s to %f m/s "
"contact %f kart %f susp %f relspeed %f",
"height %f contact %f kart %f susp %f relspeed %f",
World::getWorld()->getTimeTicks(),
impulse.getY(),
-v_down.getY(),
v_old,
m_chassisBody->getLinearVelocity().getY(),
m_ground_height[0],
m_wheelInfo[wheel_index].m_raycastInfo.m_isInContact ?
m_wheelInfo[wheel_index].m_raycastInfo.m_contactPointWS.getY()
: -100,

9
src/physics/btKart.hpp
View File

@ -11,6 +11,8 @@
#ifndef BT_KART_HPP
#define BT_KART_HPP
#include <vector>
#include "BulletDynamics/Dynamics/btRigidBody.h"
#include "BulletDynamics/ConstraintSolver/btTypedConstraint.h"
#include "physics/btKartRaycast.hpp"
@ -117,6 +119,13 @@ private:
* physics steps, so need to be set again by the application. */
btScalar m_max_speed;
/** Smallest wheel height to the ground, with a few frames of history */
std::vector<btScalar> m_ground_height;
const float HISTORY_TIME = 0.05f;
/** Used to get the smallest weel height in the current frame */
btScalar m_new_ground_height;
/** True if the visual wheels touch the ground. */
bool m_visual_wheels_touch_ground;