qcharactercontroller.cpp

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// Copyright (C) 2022 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only
 
#include "qcharactercontroller_p.h"
 
#include "physxnode/qphysxcharactercontroller_p.h"
 
QT_BEGIN_NAMESPACE
 
QCharacterController::QCharacterController() = default;
 
const QVector3D &QCharacterController::movement() const
{
    return m_movement;
}
 
void QCharacterController::setMovement(const QVector3D &newMovement)
{
    if (m_movement == newMovement)
        return;
    m_movement = newMovement;
    emit movementChanged();
}
 
const QVector3D &QCharacterController::gravity() const
{
    return m_gravity;
}
 
void QCharacterController::setGravity(const QVector3D &newGravity)
{
    if (m_gravity == newGravity)
        return;
    m_gravity = newGravity;
    emit gravityChanged();
}
 
// Calculate move based on movement/gravity
 
QVector3D QCharacterController::getDisplacement(float deltaTime)
{
    // Start with basic movement, assuming no other factors
    QVector3D displacement = sceneRotation() * m_movement * deltaTime;
 
    // modified based on gravity
    const auto g = m_gravity;
    if (!g.isNull()) {
 
        // Avoid "spider mode": we are also supposed to be in free fall if gravity
        // is pointing away from a surface we are touching. I.e. we are NOT in free
        // fall only if gravity has a component in the direction of one of the collisions.
        // Also: if we have "upwards" free fall velocity, that motion needs to stop
        // when we hit the "ceiling"; i.e we are not in free fall at the moment of impact.
        auto isGrounded = [this](){
            if (m_collisions == Collision::None)
                return false;
 
            // Standard gravity case first
            if (m_gravity.y() < 0) {
                if (m_collisions & Collision::Down)
                     return true; // We land on the ground
                if ((m_collisions & Collision::Up) && m_freeFallVelocity.y() > 0)
                    return true; // We bump our head on the way up
            }
 
            // Inverse gravity next: exactly the opposite
            if (m_gravity.y() > 0) {
                if (m_collisions & Collision::Up)
                     return true;
                if ((m_collisions & Collision::Down) && m_freeFallVelocity.y() < 0)
                    return true;
            }
 
            // The sideways gravity case can't be perfectly handled since we don't
            // know the direction of sideway contacts. We could in theory inspect
            // the mesh, but that is far too complex for an extremely marginal use case.
 
            if ((m_gravity.x() != 0 || m_gravity.z() != 0) && m_collisions & Collision::Side)
                return true;
 
            return false;
        };
 
        bool freeFalling = !isGrounded();
        if (freeFalling) {
            if (!m_midAirControl)
                displacement = {}; // Ignore the movement() controls in true free fall
 
            displacement += m_freeFallVelocity * deltaTime;
            m_freeFallVelocity += g * deltaTime;
        } else {
            m_freeFallVelocity = displacement / deltaTime + g * deltaTime;
            if (m_midAirControl) // free fall only straight down
                m_freeFallVelocity =
                        QVector3D::dotProduct(m_freeFallVelocity, g.normalized()) * g.normalized();
        }
        const QVector3D gravityAcceleration = 0.5 * deltaTime * deltaTime * g;
        displacement += gravityAcceleration; // always add gravitational acceleration, in case we start
                                             // to fall. If we don't, PhysX will move us back to the ground.
    }
 
    return displacement;
}
 
bool QCharacterController::midAirControl() const
{
    return m_midAirControl;
}
 
void QCharacterController::setMidAirControl(bool newMidAirControl)
{
    if (m_midAirControl == newMidAirControl)
        return;
    m_midAirControl = newMidAirControl;
    emit midAirControlChanged();
}
 
void QCharacterController::teleport(const QVector3D &position)
{
    m_teleport = true;
    m_teleportPosition = position;
    m_freeFallVelocity = {};
}
 
bool QCharacterController::getTeleport(QVector3D &position)
{
    if (m_teleport) {
        position = m_teleportPosition;
        m_teleport = false;
        return true;
    }
    return false;
}
 
const QCharacterController::Collisions &QCharacterController::collisions() const
{
    return m_collisions;
}
 
void QCharacterController::setCollisions(const Collisions &newCollisions)
{
    if (m_collisions == newCollisions)
        return;
    m_collisions = newCollisions;
    emit collisionsChanged();
}
 
bool QCharacterController::enableShapeHitCallback() const
{
    return m_enableShapeHitCallback;
}
 
QAbstractPhysXNode *QCharacterController::createPhysXBackend()
{
    return new QPhysXCharacterController(this);
}
 
void QCharacterController::setEnableShapeHitCallback(bool newEnableShapeHitCallback)
{
    if (m_enableShapeHitCallback == newEnableShapeHitCallback)
        return;
    m_enableShapeHitCallback = newEnableShapeHitCallback;
    emit enableShapeHitCallbackChanged();
}
 
QT_END_NAMESPACE