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
          }
      }
  }