// Copyright (C) 2020 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only

/*!
    \example particles3d
    \examplecategory {3D}
    \ingroup quick3d-examples
    \title Qt Quick 3D - Particles 3D Testbed Example
    \examplecategory {3D}
    \brief Demonstrates how to use the Qt Quick 3D Particles3D module.
    \image particles3d-testbed.jpg
           {Four windows showing different particle system examples}

    This example demonstrates different ways to use the
    \l{Qt Quick 3D Particles3D QML Types}{QtQuick3D.Particles3D}
    module features. Particles Testbed contains a collection of examples, some emphasizing a
    particular feature and some combining more features for achieving the desired appearance.

    \section1 Common Features

    The examples inside the Testbed share some common features. To exit the example back to
    launching screen, press the back arrow at the top-left corner.

    Bottom-right corner of each example contain an icon that opens the logging view.
    From this view, you can see different debug data about the particles. Each
    \l ParticleSystem3D has its own row showing its \l ParticleSystem3DLogging data.

    \image particles3d-loggingview.jpg
           {Particle system statistics and performance metrics}

    Top-right corner of the most examples contain a settings view which can be shown
    or hidden by clicking its icon. These settings help to demonstrate individual API
    features as well as the dynamic behavior of the particle systems.

    \image particles3d-settings.jpg
           {Control panel for fire, smoke, and sparkles particle effects}

    \section1 Snowing Example

    Let's go through the basics of \l{Qt Quick 3D Particles3D QML Types}
    {Particles3D} by looking at the Snowing example.

    \image particles3d-snowing.jpg
           {Two colored cubes with falling snow particles and particle settings
           panel}

    First, import the \l{Qt Quick 3D Particles3D QML Types}
    {QtQuick3D.Particles3D} module with the following statement:

    \code
    import QtQuick3D.Particles3D
    \endcode

    \l ParticleSystem3D is the root of the particle system which handles the system
    timing and groups all the other related elements like particles, emitters,
    and affectors together.

    \snippet particles3d/Snowing.qml particle system

    Then we create a \l SpriteParticle3D which is a visual 2D texture particle.
    If we would need a 3D model particles we could alternatively use \l ModelParticle3D.
    Defining the amount of particles with \l {Particle3D::maxAmount}{maxAmount} is important
    so that optimal buffer sizes get allocated. Here our snowflakes are white, with varied
    opacity and they fade in and out in 1000ms.

    \snippet particles3d/Snowing.qml sprite particle

    Next we will need \l ParticleEmitter3D to emit the above \c snowParticle particles.
    The \l {ParticleEmitter3D::shape}{shape} property defines area where emitting is done.
    Here we define snowflakes to have varied rotation and size. With the
    \l {ParticleEmitter3D::velocity}{velocity} property you can define the initial
    direction of speed of the emitted particles. Each snowflake particle exists for 15
    seconds and the \l {ParticleEmitter3D::emitRate}{emiting rate} is controlled with
    the settings sliders.

    \snippet particles3d/Snowing.qml particle emitter

    Usually also some affectors are used to make the particles movement more interesting.
    In this Snowing example we use \l Wander3D to get the snowflakes flying with wavy curves
    as well as \l PointRotator3D to simulate windy weather.

    \snippet particles3d/Snowing.qml particle affectors
*/
