- Qt 5.15
- Qt Quick 3D
- Qt Quick 3D Examples and Tutorials
- Qt Quick 3D - Lights Example
- Qt Quick 3D | Commercial or GPLv3

# Qt Quick 3D - Lights Example

Demonstrates the use of different light types.

This example demonstrates using three different light types in an application.

#### Setting the Scene Lights

##### Directional Light

The directional light emits light in one direction from an unidentifiable source located infinitely far away. This is similar to the way sunlight works in real life. A directional light has infinite range and does not diminish.

We setup directional light to emit red color and animate its rotation around x-axis.

     DirectionalLight {
         id: light1
         color: Qt.rgba(1.0, 0.1, 0.1, 1.0)
         ambientColor: Qt.rgba(0.1, 0.1, 0.1, 1.0)
         position: Qt.vector3d(0, 200, 0)
         rotation: Quaternion.fromEulerAngles(-135, -90, 0)
         shadowMapQuality: Light.ShadowMapQualityHigh
         visible: checkBox1.checked
         castsShadow: checkBoxShadows.checked
         brightness: slider1.sliderValue
         SequentialAnimation on rotation {
             loops: Animation.Infinite
             QuaternionAnimation {
                 to: Quaternion.fromEulerAngles(-45, -90, 0)
                 duration: 2000
                 easing.type: Easing.InOutQuad
             }
             QuaternionAnimation {
                 to: Quaternion.fromEulerAngles(-135, -90, 0)
                 duration: 2000
                 easing.type: Easing.InOutQuad
             }
         }
     }

##### Point Light

The point light can be described as a sphere, emitting light with equal strength in all directions from the center of the light. This is similar to the way a light bulb emits light.

We setup point light to emit green color and animate its position in x-coordinate.

     PointLight {
         id: light2
         color: Qt.rgba(0.1, 1.0, 0.1, 1.0)
         ambientColor: Qt.rgba(0.1, 0.1, 0.1, 1.0)
         position: Qt.vector3d(0, 300, 0)
         shadowMapFar: 2000
         shadowMapQuality: Light.ShadowMapQualityHigh
         visible: checkBox2.checked
         castsShadow: checkBoxShadows.checked
         brightness: slider2.sliderValue
         SequentialAnimation on x {
             loops: Animation.Infinite
             NumberAnimation {
                 to: 400
                 duration: 2000
                 easing.type: Easing.InOutQuad
             }
             NumberAnimation {
                 to: 0
                 duration: 2000
                 easing.type: Easing.InOutQuad
             }
         }
     }

##### Area Light

The area light is similar to the directional light, but instead of emitting equally bright light across the whole scene, the area light emits directional light from a rectangle shaped object. Aside from the size, an area light has the same characteristics and properties as the directional light.

We setup area light to emit blue color and animate its position in z-coordinate.

     AreaLight {
         id: light3
         color: Qt.rgba(0.1, 0.1, 1.0, 1.0)
         ambientColor: Qt.rgba(0.1, 0.1, 0.1, 1.0)
         position: Qt.vector3d(-50, 250, 150)
         eulerRotation.x: -90
         width: 1000
         height: 200
         shadowMapFar: 2000
         shadowMapQuality: Light.ShadowMapQualityHigh
         visible: checkBox3.checked
         castsShadow: checkBoxShadows.checked
         brightness: slider3.sliderValue
         SequentialAnimation on z {
             loops: Animation.Infinite
             NumberAnimation {
                 to: -150
                 duration: 2000
                 easing.type: Easing.InOutQuad
             }
             NumberAnimation {
                 to: 150
                 duration: 2000
                 easing.type: Easing.InOutQuad
             }
         }
     }

##### Spot Light

The spot light is similar to the point light, except that it emits light in a cone shape towards one direction instead of all directions. Aside from the cone angle, a spot light has the same characteristics and properties as the point light.

We setup spot light to emit a warm color and animate its rotation in y-coordinate.

     SpotLight {
         id: light4
         color: Qt.rgba(1.0, 0.9, 0.7, 1.0)
         ambientColor: Qt.rgba(0.0, 0.0, 0.0, 0.0)
         position: Qt.vector3d(0, 250, 0)
         eulerRotation.x: -45
         shadowMapFar: 2000
         shadowMapQuality: Light.ShadowMapQualityHigh
         visible: checkBox4.checked
         castsShadow: checkBoxShadows.checked
         brightness: slider4.sliderValue
         coneAngle: 50
         innerConeAngle: 30
         PropertyAnimation on eulerRotation.y {
             loops: Animation.Infinite
             from: 0
             to: -360
             duration: 10000
         }
     }

#### Setting the Scene Models

First we add two rectangle models to act as the floor and the back wall for our scene. These are useful for seeing light shadows.

     Model {
         source: "#Rectangle"
         y: -200
         scale: Qt.vector3d(15, 15, 15)
         eulerRotation.x: -90
         materials: [
             DefaultMaterial {
                 diffuseColor: Qt.rgba(0.8, 0.6, 0.4, 1.0)
             }
         ]
     }
     Model {
         source: "#Rectangle"
         z: -400
         scale: Qt.vector3d(15, 15, 15)
         materials: [
             DefaultMaterial {
                 diffuseColor: Qt.rgba(0.8, 0.8, 0.9, 1.0)
             }
         ]
     }

Then we add our main teapot model which is rotated around y-axis.

     Model {
         source: "teapot.mesh"
         y: -100
         scale: Qt.vector3d(75, 75, 75)
         materials: [
             DefaultMaterial {
                 diffuseColor: Qt.rgba(0.9, 0.9, 0.9, 1.0)
             }
         ]

         NumberAnimation  on eulerRotation.y {
             loops: Animation.Infinite
             duration: 5000
             from: 0
             to: -360
         }
     }

We also add small cube models to demonstrate position & rotation of each light type. These cubes scale bigger when user is accessing related sliders.

     Model {
         source: "#Cube"
         position: light1.position
         rotation: light1.rotation
         property real size: slider1.highlight ? 0.2 : 0.1
         scale: Qt.vector3d(size, size, size)
         materials: [
             DefaultMaterial {
                 diffuseColor: light1.color
                 opacity: 0.4
             }
         ]
     }
     Model {
         source: "#Cube"
         position: light2.position
         rotation: light2.rotation
         property real size: slider2.highlight ? 0.2 : 0.1
         scale: Qt.vector3d(size, size, size)
         materials: [
             DefaultMaterial {
                 diffuseColor: light2.color
                 opacity: 0.4
             }
         ]
     }
     Model {
         source: "#Cube"
         position: light3.position
         rotation: light3.rotation
         property real size: slider3.highlight ? 0.2 : 0.1
         scale: Qt.vector3d(size, size, size)
         materials: [
             DefaultMaterial {
                 diffuseColor: light3.color
                 opacity: 0.4
             }
         ]
     }
     Model {
         source: "#Cube"
         position: light4.position
         rotation: light4.rotation
         property real size: slider4.highlight ? 0.2 : 0.1
         scale: Qt.vector3d(size, size, size)
         materials: [
             DefaultMaterial {
                 diffuseColor: light4.color
                 opacity: 0.4
             }
         ]
     }

From the settings panel user can then enable shadows and control visibility and brightness of each light separately.

Files:

- lights/CustomCheckBox.qml
- lights/CustomSlider.qml
- lights/lights.pro
- lights/main.cpp
- lights/main.qml
- lights/qml.qrc