BarEntity.qml Example File

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 import Qt3D.Core 2.0
 import Qt3D.Render 2.0
 import Qt3D.Extras 2.0
 import QtQuick 2.4 as QQ2

 Entity {
     property int rotationTimeMs: 0
     property int entityIndex: 0
     property int entityCount: 0
     property int startAngle: 0 + 360 / entityCount * entityIndex
     property bool needsNewMagnitude: true
     property real magnitude: 0
     property real animWeight: 0

     property color lowColor: "black"
     property color highColor: "#b3b3b3"
     property color barColor: lowColor

     property string entityAnimationsState: "stopped"
     property bool entityAnimationsPlaying: true

     property var entityMesh: null

     onEntityAnimationsStateChanged: {
         if (animationState == "paused") {
             if (angleAnimation.running)
                 angleAnimation.pause()
             if (barColorAnimations.running)
                 barColorAnimations.pause()
         } else if (animationState == "playing"){
             needsNewMagnitude = true;
             if (heightDecreaseAnimation.running)
                 heightDecreaseAnimation.stop()
             if (angleAnimation.paused) {
                 angleAnimation.resume()
             } else if (!entityAnimationsPlaying) {
                 magnitude = 0
                 angleAnimation.start()
                 entityAnimationsPlaying = true
             }
             if (barColorAnimations.paused)
                 barColorAnimations.resume()
         } else {
             if (animWeight != 0)
                 heightDecreaseAnimation.start()
             needsNewMagnitude = true
             angleAnimation.stop()
             barColorAnimations.stop()
             entityAnimationsPlaying = false
         }
     }

     property Material barMaterial: PhongMaterial {
         diffuse: barColor
         ambient: Qt.darker(barColor)
         specular: "black"
         shininess: 1
     }

     property Transform angleTransform: Transform {
         property real heightIncrease: magnitude * animWeight
         property real barAngle: startAngle

         matrix: {
             var m = Qt.matrix4x4()
             m.rotate(barAngle, Qt.vector3d(0, 1, 0))
             m.translate(Qt.vector3d(1.1, heightIncrease / 2 - heightIncrease * 0.05, 0))
             m.scale(Qt.vector3d(0.5, heightIncrease * 15, 0.5))
             return m;
         }

         property real compareAngle: barAngle
         onBarAngleChanged: {
             compareAngle = barAngle

             if (compareAngle > 360)
                 compareAngle = barAngle - 360

             if (compareAngle > 180) {
                 parent.enabled = false
                 animWeight = 0
                 if (needsNewMagnitude) {
                     // Calculate the ms offset where the bar will be at the center point of the
                     // visualization and fetch the correct magnitude for that point in time.
                     var offset = (90.0 + 360.0 - compareAngle) * (rotationTimeMs / 360.0)
                     magnitude = mediaPlayer.getNextAudioLevel(offset)
                     needsNewMagnitude = false
                 }
             } else {
                 parent.enabled = true
                 // Calculate a power of 2 curve for the bar animation that peaks at 90 degrees
                 animWeight = Math.min((compareAngle / 90), (180 - compareAngle) / 90)
                 animWeight = animWeight * animWeight
                 if (!needsNewMagnitude) {
                     needsNewMagnitude = true
                     barColorAnimations.start()
                 }
             }
         }
     }

     components: [entityMesh, barMaterial, angleTransform]

     QQ2.NumberAnimation {
         id: angleAnimation
         target: angleTransform
         property: "barAngle"
         duration: rotationTimeMs
         loops: QQ2.Animation.Infinite
         running: true
         from: startAngle
         to: 360 + startAngle
     }

     QQ2.NumberAnimation {
         id: heightDecreaseAnimation
         target: angleTransform
         property: "heightIncrease"
         duration: 400
         running: false
         from: angleTransform.heightIncrease
         to: 0
         onStopped: barColor = lowColor
     }

     property int animationDuration: angleAnimation.duration / 6

     QQ2.SequentialAnimation on barColor {
         id: barColorAnimations
         running: false

         QQ2.ColorAnimation {
             from: lowColor
             to: highColor
             duration: animationDuration
         }

         QQ2.PauseAnimation {
             duration: animationDuration
         }

         QQ2.ColorAnimation {
             from: highColor
             to: lowColor
             duration: animationDuration
         }
     }
 }