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Just some notes for future maintenance.

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actorid
cc9cii 11 years ago
parent 87ae03b5d4
commit 772a49b2a6
1 changed files with 91 additions and 11 deletions
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102
apps/openmw/mwworld/physicssystem.cpp
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@ -50,25 +50,102 @@ namespace MWWorld
const Ogre::Vector3 &velocity, float &remainingTime,
OEngine::Physic::PhysicEngine *engine)
{
/*
* Slide up an incline or set of stairs. Should be called only after a
* collision detection otherwise unnecessary tracing will be performed.
*
* NOTE: with a small change this method can be used to step over an obstacle
* of height sStepSize.
*
* If successful return 'true' and update 'position' to the new possible
* location and adjust 'remainingTime'.
*
* If not successful return 'false'. May fail for these reasons:
* - can't move directly up from current position
* - having moved up by between epsilon() and sStepSize, can't move forward
* - having moved forward by between epsilon() and velocity*remainingTime,
* = moved down between 0 and just under sStepSize but slope was too steep, or
* = moved the full sStepSize down (FIXME: this could be a bug)
*
*
*
* Starting position. Obstacle or stairs with height upto sStepSize in front.
*
* +--+ +--+ |XX
* | | -------> velocity | | +--+XX
* | | | | |XXXXX
* | | +--+ | | +--+XXXXX
* | | |XX| | | |XXXXXXXX
* +--+ +--+ +--+ +--------
* ==============================================
*/
/*
* Try moving up sStepSize using stepper.
* FIXME: does not work in case there is no front obstacle but there is one above
*
* +--+ +--+
* | | | |
* | | | | |XX
* | | | | +--+XX
* | | | | |XXXXX
* +--+ +--+ +--+ +--+XXXXX
* |XX| |XXXXXXXX
* +--+ +--------
* ==============================================
*/
OEngine::Physic::ActorTracer tracer, stepper;
stepper.doTrace(colobj, position, position+Ogre::Vector3(0.0f,0.0f,sStepSize), engine);
if(stepper.mFraction < std::numeric_limits<float>::epsilon())
return false;
return false; // didn't even move the smallest representable amount
// (TODO: shouldn't this be larger? Why bother with such a small amount?)
/*
* Try moving from the elevated position using tracer.
*
* +--+ +--+
* | | |YY| FIXME: collision with object YY
* | | +--+
* | |
* <------------------->| |
* +--+ +--+
* |XX| the moved amount is velocity*remainingTime*tracer.mFraction
* +--+
* ==============================================
*/
tracer.doTrace(colobj, stepper.mEndPos, stepper.mEndPos + velocity*remainingTime, engine);
if(tracer.mFraction < std::numeric_limits<float>::epsilon())
return false;
return false; // didn't even move the smallest representable amount
/*
* Try moving back down sStepSize using stepper.
* NOTE: if there is an obstacle below (e.g. stairs), we'll be "stepping up".
* Below diagram is the case where we "stepped over" an obstacle in front.
*
* +--+
* |YY|
* +--+ +--+
* | |
* | |
* +--+ | |
* |XX| | |
* +--+ +--+
* ==============================================
*/
stepper.doTrace(colobj, tracer.mEndPos, tracer.mEndPos-Ogre::Vector3(0.0f,0.0f,sStepSize), engine);
if(stepper.mFraction < 1.0f && getSlope(stepper.mPlaneNormal) <= sMaxSlope)
{
// only step down onto semi-horizontal surfaces. don't step down onto the side of a house or a wall.
// TODO: stepper.mPlaneNormal does not appear to be reliable - needs more testing
// NOTE: caller's variables 'position' & 'remainingTime' are modified here
position = stepper.mEndPos;
remainingTime *= (1.0f-tracer.mFraction);
remainingTime *= (1.0f-tracer.mFraction); // remaining time is proportional to remaining distance
return true;
}
// moved between 0 and just under sStepSize distance but slope was too great,
// or moved full sStepSize distance (FIXME: is this a bug?)
return false;
}
@ -164,26 +241,27 @@ namespace MWWorld
{
velocity = Ogre::Quaternion(Ogre::Radian(refpos.rot[2]), Ogre::Vector3::NEGATIVE_UNIT_Z) * movement;
// not in water nor can fly, so need to deal with gravity
if(!physicActor->getOnGround())
if(!physicActor->getOnGround()) // if current OnGround status is false, must be falling or jumping
{
// If falling, add part of the incoming velocity with the current inertia
// TODO: but we could be jumping up?
velocity = velocity * time + physicActor->getInertialForce();
}
inertia = velocity; // REM velocity is for z axis only in this code block
inertia = velocity; // NOTE: velocity is for z axis only in this code block
if(!(movement.z > 0.0f))
if(!(movement.z > 0.0f)) // falling or moving horizontally (or stationary?) check if we're on ground now
{
wasOnGround = physicActor->getOnGround();
// TODO: Find out if there is a significance with the value 2 used here
tracer.doTrace(colobj, position, position - Ogre::Vector3(0,0,2), engine);
wasOnGround = physicActor->getOnGround(); // store current state
tracer.doTrace(colobj, position, position - Ogre::Vector3(0,0,2), engine); // check if down 2 possible
if(tracer.mFraction < 1.0f && getSlope(tracer.mPlaneNormal) <= sMaxSlope)
isOnGround = true;
}
}
// NOTE: isOnGround was initialised false, so should stay false if falling or sliding horizontally
if(isOnGround)
{
// if we're on the ground, don't try to fall
// if we're on the ground, don't try to fall any more
velocity.z = std::max(0.0f, velocity.z); // NOTE: two different velocity assignments above
}
@ -196,6 +274,7 @@ namespace MWWorld
float remainingTime = time;
for(int iterations = 0; iterations < sMaxIterations && remainingTime > 0.01f; ++iterations)
{
// NOTE: velocity is either z axis only or x & z axis
Ogre::Vector3 nextpos = newPosition + velocity * remainingTime;
// If not able to fly, walk or bipedal don't allow to move out of water
@ -229,8 +308,9 @@ namespace MWWorld
break;
}
// We hit something. Try to step up onto it.
// We hit something. Try to step up onto it. (NOTE: stepMove does not allow stepping over)
// NOTE: May need to stop slaughterfish step out of the water.
// NOTE: stepMove may modify newPosition
if((canWalk || isBipedal || isNpc) && stepMove(colobj, newPosition, velocity, remainingTime, engine))
isOnGround = !(newPosition.z < waterlevel || isFlying); // Only on the ground if there's gravity
else

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