PxVehicleComponentSequence.h

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// Copyright (c) 2008-2022 NVIDIA Corporation. All rights reserved.
// Copyright (c) 2004-2008 AGEIA Technologies, Inc. All rights reserved.
// Copyright (c) 2001-2004 NovodeX AG. All rights reserved.  
 
#pragma once
#include "foundation/PxAssert.h"
#include "foundation/PxErrors.h"
#include "foundation/PxFoundation.h"
#include "PxVehicleComponent.h"
 
#if !PX_DOXYGEN
namespace physx
{
namespace vehicle2
{
#endif
 
 
struct PxVehicleComponentSequenceLimits
{
    enum Enum
    {
        eMAX_NB_SUBGROUPS = 16,
        eMAX_NB_COMPONENTS = 64,
        eMAX_NB_SUBGROUPELEMENTS = eMAX_NB_SUBGROUPS + eMAX_NB_COMPONENTS
    };
};
 
struct PxVehicleComponentSequence
{
    enum
    {
        eINVALID_SUBSTEP_GROUP = 0xff
    };
 
    PxVehicleComponentSequence()
        : mNbComponents(0), mNbSubgroups(1), mNbSubGroupElements(0), mActiveSubgroup(0)
    {
    }
 
    PX_FORCE_INLINE bool add(PxVehicleComponent* component);
 
    PX_FORCE_INLINE PxU8 beginSubstepGroup(const PxU8 nbSubSteps = 1);
 
    PX_FORCE_INLINE void endSubstepGroup()
    {
        mActiveSubgroup = mSubGroups[mActiveSubgroup].parentGroup;
    }
 
    void setSubsteps(const PxU8 subGroupHandle, const PxU8 nbSteps)
    {
        PX_ASSERT(subGroupHandle < mNbSubgroups);
        mSubGroups[subGroupHandle].nbSteps = nbSteps;
    }
 
    void update(const PxReal dt, const PxVehicleSimulationContext& context)
    {
        PX_ASSERT(0 == mActiveSubgroup);
 
        if (dt > 0.0f)
        {
            updateSubGroup(dt, context, 0, 1);
        }
        else
        {
            PxGetFoundation().error(PxErrorCode::eINVALID_PARAMETER, __FILE__, __LINE__,
                "PxVehicleComponentSequence::update: The timestep must be positive!");
        }
    }
 
private:
    enum
    {
        eINVALID_COMPONENT = 0xff,
        eINVALID_SUB_GROUP_ELEMENT = 0xff
    };
 
    //Elements have the form of a linked list to allow traversal over a list of elements.
    //Each element is either a single component or a subgroup.
    struct SubGroupElement
    {
        SubGroupElement()
            : childGroup(eINVALID_SUBSTEP_GROUP),
            component(eINVALID_COMPONENT),
            nextElement(eINVALID_SUB_GROUP_ELEMENT)
        {
        }
 
        PxU8 childGroup;
        PxU8 component;
        PxU8 nextElement;
    };
 
    //A group is a linked list of  elements to be processed in sequence.
    //Each group stores the first element in the sequence.
    //Each element in the sequence stores the next element in the sequence
    //to allow traversal over the  list of elements in the group.
    struct Group
    {
        Group()
            : parentGroup(eINVALID_SUBSTEP_GROUP),
            firstElement(eINVALID_SUB_GROUP_ELEMENT),
            nbSteps(1)
        {
        }
        PxU8 parentGroup;
        PxU8 firstElement;
        PxU8 nbSteps;
    };
 
    PxVehicleComponent* mComponents[PxVehicleComponentSequenceLimits::eMAX_NB_COMPONENTS];
    PxU8 mNbComponents;
 
    Group mSubGroups[PxVehicleComponentSequenceLimits::eMAX_NB_SUBGROUPS];
    PxU8 mNbSubgroups;
 
    SubGroupElement mSubGroupElements[PxVehicleComponentSequenceLimits::eMAX_NB_SUBGROUPELEMENTS];
    PxU8 mNbSubGroupElements;
 
    PxU8 mActiveSubgroup;
 
    bool updateSubGroup(const PxReal dt, const PxVehicleSimulationContext& context, const PxU8 groupId, const PxU8 parentSepMultiplier)
    {
        const PxU8 nbSteps = mSubGroups[groupId].nbSteps;
        const PxU8 stepMultiplier = parentSepMultiplier * nbSteps;
        const PxReal timestepForGroup = dt / PxReal(stepMultiplier);
        for (PxU8 k = 0; k < nbSteps; k++)
        {
            PxU8 nextElement = mSubGroups[groupId].firstElement;
            while (eINVALID_SUB_GROUP_ELEMENT != nextElement)
            {
                const SubGroupElement& e = mSubGroupElements[nextElement];
                PX_ASSERT(e.component != eINVALID_COMPONENT || e.childGroup != eINVALID_SUBSTEP_GROUP);
                if (eINVALID_COMPONENT != e.component)
                {
                    PxVehicleComponent* c = mComponents[e.component];
                    if (!c->update(timestepForGroup, context))
                        return false;
                }
                else
                {
                    PX_ASSERT(eINVALID_SUBSTEP_GROUP != e.childGroup);
                    if (!updateSubGroup(dt, context, e.childGroup, stepMultiplier))
                        return false;
                }
                nextElement = e.nextElement;
            }
        }
 
        return true;
    }
 
    PxU8 getLastKnownElementInGroup(const PxU8 groupId) const
    {
        PxU8 currElement = mSubGroups[groupId].firstElement;
        PxU8 nextElement = mSubGroups[groupId].firstElement;
        while (nextElement != eINVALID_SUB_GROUP_ELEMENT)
        {
            currElement = nextElement;
            nextElement = mSubGroupElements[nextElement].nextElement;
        }
        return currElement;
    }
};
 
 
bool PxVehicleComponentSequence::add(PxVehicleComponent* c)
{
    if (PxVehicleComponentSequenceLimits::eMAX_NB_COMPONENTS == mNbComponents)
        return false;
    if (PxVehicleComponentSequenceLimits::eMAX_NB_SUBGROUPELEMENTS == mNbSubGroupElements)
        return false;
 
    //Create a new element and point it at the component.
    SubGroupElement& nextElementInGroup = mSubGroupElements[mNbSubGroupElements];
    nextElementInGroup.childGroup = eINVALID_SUBSTEP_GROUP;
    nextElementInGroup.component = mNbComponents;
    nextElementInGroup.nextElement = eINVALID_SUB_GROUP_ELEMENT;
 
    if (eINVALID_SUB_GROUP_ELEMENT == mSubGroups[mActiveSubgroup].firstElement)
    {
        //The group is empty so add the first element to it.
        //Point the group at the new element because this will 
        //be the first element in the group.
        mSubGroups[mActiveSubgroup].firstElement = mNbSubGroupElements;
    }
    else
    {
        //We are extending the sequence of element of the group.            
        //Add the new element to the end of the group's sequence.
        mSubGroupElements[getLastKnownElementInGroup(mActiveSubgroup)].nextElement = mNbSubGroupElements;
    }
 
    //Increment the number of elements.
    mNbSubGroupElements++;
 
    //Record the component and increment the number of components.
    mComponents[mNbComponents] = c;
    mNbComponents++;
 
    return true;
}
 
PxU8 PxVehicleComponentSequence::beginSubstepGroup(const PxU8 nbSubSteps)
{
    if (mNbSubgroups == PxVehicleComponentSequenceLimits::eMAX_NB_SUBGROUPS)
        return eINVALID_SUBSTEP_GROUP;
    if (mNbSubGroupElements == PxVehicleComponentSequenceLimits::eMAX_NB_SUBGROUPELEMENTS)
        return eINVALID_SUBSTEP_GROUP;
 
    //We have a parent and child group relationship.
    const PxU8 parentGroup = mActiveSubgroup;
    const PxU8 childGroup = mNbSubgroups;
 
    //Set up the child group.
    mSubGroups[childGroup].parentGroup = parentGroup;
    mSubGroups[childGroup].firstElement = eINVALID_SUB_GROUP_ELEMENT;
    mSubGroups[childGroup].nbSteps = nbSubSteps;
 
    //Create a new element to add to the parent group and point it at the child group.
    SubGroupElement& nextElementIInGroup = mSubGroupElements[mNbSubGroupElements];
    nextElementIInGroup.childGroup = childGroup;
    nextElementIInGroup.nextElement = eINVALID_SUB_GROUP_ELEMENT;
    nextElementIInGroup.component = eINVALID_COMPONENT;
 
    //Add the new element to the parent group.
    if (eINVALID_SUB_GROUP_ELEMENT == mSubGroups[parentGroup].firstElement)
    {
        //The parent group is empty so add the first element to it.
        //Point the parent group at the new element because this will 
        //be the first element in the group.
        mSubGroups[parentGroup].firstElement = mNbSubGroupElements;
    }
    else
    {
        //We are extending the sequence of elements of the parent group.            
        //Add the new element to the end of the group's sequence.
        mSubGroupElements[getLastKnownElementInGroup(parentGroup)].nextElement = mNbSubGroupElements;
    }
 
    //Push the active group.
    //All subsequent operations will now address the child group and we push or pop the group.
    mActiveSubgroup = childGroup;
 
    //Increment the number of elements.
    mNbSubGroupElements++;
 
    //Increment the number of groups.
    mNbSubgroups++;
 
    //Return the group id.
    return mActiveSubgroup;
}
 
#if !PX_DOXYGEN
} // namespace vehicle2
} // namespace physx
#endif