Qt 3D: Planets QML Example

Demonstrates combining Qt 3D rendering and Qt Quick 2 elements

Demonstrates combining Qt 3D rendering and Qt Quick 2 elements.

Planets demonstrates how to implement an application that combines the use of Qt 3D rendering with Qt Quick 2D elements. The example shows the eight planets of our Solar System with the Sun.

Planet texture maps are Copyright (c) by James Hastings-Trew http://planetpixelemporium.com/planets.html used with permission.

The planets are rotating around the Sun based on their orbit at a given time. The rotation starts at 2000 Jan 0.0 UT. The planet positions are calculated based on the formulas found here: http://www.stjarnhimlen.se/comp/ppcomp.html and http://www.davidcolarusso.com/astro/.

Running the Example

To run the example from Qt Creator , open the Welcome mode and select the example from Examples . For more information, visit Building and Running an Example.

Qt Quick 2D Implementation

The Qt Quick Implementation PlanetsMain.qml of the example renders the 3D content using the Scene3D type.

Scene3D {
    anchors.fill: parent
    aspects: ["render", "logic", "input"]

    SolarSystem { id: solarsystem }
}

The planet related information is stored into a ListModel . The selection buttons for the planets and the information sheet are created based on the model. The 2D elements, selection buttons and sliders, are implemented in the PlanetsMain.qml .

The selection buttons change the focusedPlanet property of the mainview . As the property changes, the planet information is updated, and the camera is animated to the new position.

onFocusedPlanetChanged: {
    if (focusedPlanet == 100) {
        info.opacity = 0
        updatePlanetInfo()
    } else {
        updatePlanetInfo()
        info.opacity = 1
    }

    solarsystem.changePlanetFocus(oldPlanet, focusedPlanet)
    oldPlanet = focusedPlanet
}

The camera position and the camera look at point are updated based on values that are animated in the SolarSystem.qml , triggered from the changePlanetFocus() function.

QQ2.NumberAnimation {
    id: lookAtOffsetAnimation
    target: sceneRoot
    properties: "xLookAtOffset, yLookAtOffset, zLookAtOffset"
    to: 0
    easing.type: Easing.InOutQuint
    duration: 1250
}

QQ2.NumberAnimation {
    id: cameraOffsetAnimation
    target: sceneRoot
    properties: "xCameraOffset, yCameraOffset, zCameraOffset"
    to: 0
    easing.type: Easing.InOutQuint
    duration: 2500
}

The sliders are used to adjust the rotation speed, the planet size, and the viewing distance. When a slider value changes, a JavaScript function in SolarSystem.qml is called to adjust the given property. For example, changing the value of the Viewing Distance slider calls the changeCameraDistance() method.

onValueChanged: solarsystem.changeCameraDistance(value)

Qt 3D Implementation

The main part of the implementation, including the movement and rotation maths for the planets, is done in the SolarSystem.qml .

First, a Camera , a Light , and a Configuration are added, followed by Effect s for the planet Material s, and finally the planets themselves. For example, Earth is constructed as follows:

Entity {
    id: earthEntity

    Planet {
        id: earth
        tilt: planetData[Planets.EARTH].tilt
    }

    PlanetMaterial {
        id: materialEarth
        effect: effectDSB
        ambientLight: ambientStrengthPlanet
        diffuseMap: "qrc:/images/solarsystemscope/earthmap2k.jpg"
        specularMap: "qrc:/images/solarsystemscope/earthspec2k.jpg"
        normalMap: "qrc:/images/solarsystemscope/earthnormal2k.jpg"
        shininess: shininessSpecularMap
    }

    property Transform transformEarth: Transform {
        matrix: {
            var m = Qt.matrix4x4()
            m.translate(Qt.vector3d(earth.x, earth.y, earth.z))
            m.rotate(earth.tilt, tiltAxis)
            m.rotate(earth.roll, rollAxis)
            m.scale(earth.r)
            return m
        }
    }

    components: [ earth, materialEarth, transformEarth ]
}

Planet data, which is needed for the movement and rotation calculations, among other things, is constructed with JavaScript in planets.js by calling loadPlanetData() as the component completes. Other initializations, such as inserting the planets into an array for easier handling, calculating the ring radii for Saturn and Uranus rings, and setting the default scale, speed, and camera offset, are done as well:

QQ2.Component.onCompleted: {
    planetData = Planets.loadPlanetData()
    // Push in the correct order
    planets.push(sun)
    planets.push(mercury)
    planets.push(venus)
    planets.push(earth)
    planets.push(mars)
    planets.push(jupiter)
    planets.push(saturn)
    planets.push(uranus)
    planets.push(neptune)
    planets.push(moon)
    // TODO: Once support for creating meshes from arrays is implemented take these into use
    //saturnRing.makeRing()
    //uranusRing.makeRing()
    saturnRingOuterRadius = planetData[Planets.SATURN].radius + Planets.saturnOuterRadius
    saturnRingInnerRadius = planetData[Planets.SATURN].radius + 6.630
    uranusRingOuterRadius = planetData[Planets.URANUS].radius + Planets.uranusOuterRadius
    uranusRingInnerRadius = planetData[Planets.URANUS].radius + 2
    ready = true
    changeScale(1200)
    changeSpeed(0.2)
    setLookAtOffset(Planets.SUN)
}

The scene is animated by calling the animate() function. That is also the place where the time is advanced, and the new positions for all of the planets are calculated. The planets are rotated in the positionPlanet() function based on their axial tilt and their sidereal rotation period. Finally, the new camera position is calculated in the updateCamera() function.

function animate(focusedPlanet) {
    if (!ready)
        return

    advanceTime(focusedPlanet)
    for (var i = 0; i <= Planets.NUM_SELECTABLE_PLANETS; i++)
        positionPlanet(i)

    updateCamera(focusedPlanet)
}

AppleTVInput.qml Example File

FpsDisplay.qml Example File

InfoSheet.qml Example File

Planet.qml Example File

PlanetButton.qml Example File

PlanetEffect.qml Example File

PlanetFrameGraph.qml Example File

PlanetMaterial.qml Example File

PlanetsLight.qml Example File

PlanetsMain.qml Example File

Ring.qml Example File

ShadowEffect.qml Example File

SolarSystem.qml Example File

StyledSlider.qml Example File

SunEffect.qml Example File

networkcontroller.cpp Example File

networkcontroller.h Example File

planets.js Example File

AndroidManifest.xml Example File

AppDelegate.h Example File

ViewController.h Example File

ExtensionDelegate.h Example File

InterfaceController.h Example File

planetD.vert Example File

planetDB.vert Example File

sun.vert Example File

planetD.vert Example File

planetDB.vert Example File

planetDShadow.vert Example File

shadowmap.vert Example File

sun.vert Example File

main.cpp Example File

planets-qml-images.qrc Example File

planets-qml.pro Example File

planets-qml.qrc Example File

icon.png Image File

icon.png Image File

icon.png Image File

earth.png Image File

jupiter.png Image File

mars.png Image File

mercury.png Image File

neptune.png Image File

saturn.png Image File

sun.png Image File

uranus.png Image File

venus.png Image File

uranusringcolortrans.png Image File

earthcloudmapcolortrans.png Image File

earthcloudmapspec.jpg Image File

earthmap2k.jpg Image File

earthnormal2k.jpg Image File

earthspec2k.jpg Image File

galaxy_starfield.jpg Image File

jupitermap.jpg Image File

marsmap2k.jpg Image File

marsnormal2k.jpg Image File

mercurymap.jpg Image File

mercurynormal.jpg Image File

moonmap2k.jpg Image File

moonnormal2k.jpg Image File

neptunemap.jpg Image File

saturnmap.jpg Image File

saturnringcolortrans.png Image File

sunmap.jpg Image File

uranusmap.jpg Image File

venusmap.jpg Image File

venusnormal.jpg Image File

icon120.png Image File

icon180.png Image File

home_icon.png Image File