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Details

Type: Bug
Resolution: Done
Priority: P1: Critical
Fix Version/s: 6.3.0 Beta3, 6.4.0 Beta1
Affects Version/s: 6.2.3, 6.4.0 FF
Component/s: Quick: 3D
Labels:
None

Commits:
62a2a1cf75 (qt/qtquick3d/dev) 56af61b930 (qt/qtquick3d/6.3) 56af61b930 (qt/qtquick3d/6.3.0) 56af61b930 (qt/tqtc-qtquick3d/6.3.0)
Sprint:
Qt Quick 3D: Week 7 - 8

Description

The shadow map of a light gets gradually lighter the closer it is to the object or light (unsure which it is).

import QtQuick
import QtQuick.Window
import QtQuick3D

Window {
    width: 640
    height: 480
    visible: true
    title: qsTr("Hello World")

    View3D {
        id: view
        anchors.fill: parent

        PerspectiveCamera {
            position: Qt.vector3d(0, 200, 300)
            eulerRotation.x: -30
        }

        DirectionalLight {
            eulerRotation: Qt.vector3d(-30, -30, -30)
            castsShadow: true
        }

        Model {
            id: cube
            source: "#Cube"

            materials: PrincipledMaterial {
                baseColor: "red"
            }
            scale: Qt.vector3d(10, 1, 10)
        }

        Model {
            id: cube2
            source: "#Cube"
            materials: PrincipledMaterial {
                baseColor: "green"
            }
            position: Qt.vector3d(-100, 150, 0)
        }

        Model {
            id: cube3
            source: "#Cube"
            materials: PrincipledMaterial {
                baseColor: "yellow"
            }
            position: Qt.vector3d(-100, 250, 0)
        }
    }
}

This example shows a green and yellow (out of camera bounds) cube hovering over a red cube and lit by a directional light. The shadow map fades out towards the cubes.

With Qt 6.2 branch:

With dev branch, a new bug has snuck in. The shadow map of the yellow and green cube are now added together so that the shadows become darker in the area where both appear.

With dev branch:

With a point light, you see some of the same things. Since the point light is the only light in the scene, you would expect the cube's shadow to be completely black (just like the cube sides that are facing away from the light). Instead it is a gradient from red to a bit darker red.

With 6.2 branch (same with dev):

Interestingly, pixels that are outside attenuation range of the point light are actually darker than the darkest pixels inside the shadow, where the light does not reach at all.

Example with point light:

import QtQuick
import QtQuick.Window
import QtQuick3D

Window {
    width: 640
    height: 480
    visible: true
    title: qsTr("Hello World")

    View3D {
        id: view
        anchors.fill: parent

        PerspectiveCamera {
            position: Qt.vector3d(0, 200, 300)
            eulerRotation.x: -30
        }

        PointLight {
            position: Qt.vector3d(-300, 300, 0)
            castsShadow: true
        }

        Model {
            id: cube
            source: "#Cube"

            materials: PrincipledMaterial {
                baseColor: "red"
            }
            scale: Qt.vector3d(10, 1, 10)
        }

        Model {
            id: cube2
            source: "#Cube"
            materials: PrincipledMaterial {
                baseColor: "green"
            }
            position: Qt.vector3d(-100, 150, 0)
        }

        Model {
            id: cube3
            source: "#Cube"
            materials: PrincipledMaterial {
                baseColor: "yellow"
            }
            position: Qt.vector3d(-100, 250, 0)
        }

    }
}