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++ // Copyright (C) 2022 The Qt Company Ltd.
++ // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only
++
++ /*!
++ \example impeller
++ \ingroup quick3dphysics-examples
++ \title Qt Quick 3D Physics - Impeller Example
++ \examplecategory {3D}
++ \brief Demonstrates using trigger bodies and collision info.
++ \image impeller-example.jpg {Screenshot of a 3D rendering showing a blue sphere on a green surface, a pink rectangular block above it,
++ and a red sphere floating on top}
++
++ This example demonstrates how to use trigger bodies and collision info.
++ The scene consists of a green static plane, a red dynamic sphere, a pink box trigger and a blue static sphere.
++ When the red sphere overlaps the trigger body it will turn yellow and when it collides with the blue sphere it will be repelled away.
++
++ \section1 Setup
++
++ As usual we need to add our PhysicsWorld:
++
++ \snippet impeller/main.qml world
++
++ We also add a View3D where we put our scene objects.
++ In this we have some settings for the visual environment:
++
++ \snippet impeller/main.qml environment
++
++ \section1 Physical objects
++
++ We have our regular static plane:
++
++ \snippet impeller/main.qml plane
++
++ This is how our dynamic sphere is defined:
++
++ \snippet impeller/main.qml sphere
++
++ The property \c inArea is a custom property we use to keep track of when the sphere is overlapping the box trigger body.
++ This is then used for the \c baseColor property to make the sphere yellow when it is overlapping the box and red otherwise.
++ Since we want the sphere to partake in contact reporting the property \l {PhysicsNode::} {sendContactReports} needs to be set to \c true.
++ Since we also want the sphere to get callbacks when entering and leaving a TriggerBody, the property
++ \l {PhysicsNode::} {receiveContactReports} is also set to \c true.
++ We implement the \l {PhysicsNode::} {enteredTriggerBody} and \l {PhysicsNode::} {exitedTriggerBody} signal methods
++ on the sphere where we set the \c inArea property to \c true or \c false when entering or leaving the trigger body.
++
++ Now let's look at the trigger body:
++
++ \snippet impeller/main.qml box
++
++ The qml type is a TriggerBody which acts like a static body except its collisions are inactive.
++ Instead it will trigger \l {PhysicsNode::} {enteredTriggerBody} and \l {PhysicsNode::} {exitedTriggerBody} method calls on the sphere.
++
++ Finally, lets look at the impeller:
++
++ \snippet impeller/main.qml impeller
++
++ This is a static body and we set \l {PhysicsNode::} {receiveContactReports} to \c true to enable the collision callbacks.
++ The callback \l {PhysicsNode::} {bodyContact} gets called whenever a collision is reported.
++ In the method we call \l{DynamicRigidBody::}{setLinearVelocity} to set the linear velocity
++ in the opposite direction of the collision normal vector to simulate an impeller.
++ */