How to rotate object in 3D space about its axis

SpyerGame

I want to rotate an object (export from balsam tool) in 3D space with roll, pitch and yaw of its object in Node but the axes of rotation is different from its object.
With 'rotX, rotY, rotZ' after some rotate , these are not pitch and roll and yaw of object!!!
In other words, I wanna rotate about body frame not initial frame!
Here is my code:

//object.qml
import QtQuick3D 1.12
import QtQuick 2.12

Node {
    id: rootNode
    rotationOrder: Node.XYZr
    orientation: Node.RightHanded

    property real rotX: 0
    property real rotY: 0
    property real rotZ: 0

    PointLight {
        id: light
        x: 100
        y: 100
        z: 100
        rotationOrder: Node.XYZr
        orientation: Node.RightHanded
        color: "#ffffffff"
        quadraticFade: -1
    }


    OrthographicCamera {
        id: cameraOrthographicFront
        z: -600
        rotation: Qt.vector3d(0, 0, 0)
    }

    Model {
        id: object
        rotation.x: rotX 
        rotation.y: rotY
        rotation.z: rotZ 
        scale.x: 100/3
        scale.y: 100/3
        scale.z: 100/3
        rotationOrder: Node.XYZr
        orientation: Node.RightHanded
        source: "meshes/object.mesh"

        DefaultMaterial {
            id: material_003_material
            diffuseMap: Texture {
                source: 'maps/pan.jpg'
                tilingModeHorizontal: Texture.Repeat
                tilingModeVertical: Texture.Repeat
            }
        }
        materials: [ material_003_material ]
    }}
}

//main.qml
mport QtQuick 2.14
import QtQuick.Window 2.1
import QtQuick3D 1.12
Window {
    id: windowMain
    visible: true
    minimumWidth: 600
    minimumHeight: 500
    width: 600
    height: 500
    color: "transparent"//

    object{ id: obj}

    Item {
        id: root
        anchors.fill: parent
        Rectangle {
            id: object3d
            anchors.centerIn: parent
            width: 400;height: width
            View3D {
                id: mode
                anchors.fill: parent
                anchors.centerIn: parent
                importScene: obj
                focus: true

                Keys.onPressed: {
                    switch (event.key) {
                    case Qt.Key_Up:
                        obj.rotX -= 1
                        break;
                    case Qt.Key_Down:
                        obj.rotX += 1;
                        break;
                    case Qt.Key_Left:
                        obj.rotY += 1;console.log('roll: ',obj.rotY)
                        break;
                    case Qt.Key_Right:
                        obj.rotZ += 1;console.log('yaw: ',obj.rotZ)
                        break;
                    default:
                        break;
                    }
                }
            }
        }
}

there is similar quest bot did not solve
link text
and this annot access:
https://forum.qt.io/topic/81457/problem-with-qt3d-rotation-about-axis-of-object

gde23

Lets say you have your object in its object coordinate system which is somehow arranged in space (rotated translated).
Then to achieve a rotation of the object about its own local object coordinate system you need to first rotate the object (as long as it still in the origin xyz coordinate system) and then apply the rotation that positions it in space afterwards. So the order of the rotations / translations is what makes the difference.

SpyerGame

@gde23 ur mean is after apply e.g. 'rotX = 25' then rotate the camera in x axis equal 25 degrees?
Can u make example for this prb?

gde23

I assume your object is made up of triangles or points or whatever and each of these points is defined in the local coordinate system of the object.

Now as long as you do not translate/rotate your object, the local coordinate system will be the same as the global coordinate system. In this position now when you just rotate about x the object will pitch if you rotate about y it will roll and z yaw. Therefore if you first apply the picht/roll/yaw rotation matrix and afterwards the transformation to the global coordinate system it will be the same as if you first positioned the object in global coordinate system and afterwards rotate about those new rotated axes. (Which however would be more complicated math)

SpyerGame

Yes, exactly at the first time two coordinates are matching but must a way for any time and robust !

kshegunov

The rotation property is a quaternion, which is rather hard to reason about directly. I'd suggest using a QTransform attached to your node instead.

SpyerGame

@kshegunov Thanks, but I don't figure out completely!
Cause Qtransform is in C++ and there is not in qml and how to use it

gde23

It does not matter if you use quaternions or rotation/homgenious matrices for the rotations/translations as long as you keep the order.
The advantage of rotation matrices however is, that you can multiply them to get a single matrix that does all the rotations at once.

SpyerGame

Are these methods useful for my prb?
@gde23 in Model scope for rotation.x: property, I put this?

SpyerGame

I Can't to solve this, yet!!

kshegunov

@gde23 said in How to rotate object in 3D space about its axis:

It does not matter if you use quaternions or rotation/homgenious matrices for the rotations/translations as long as you keep the order.

Not in principle, as it is just a matter of representation. Utility and convenience however can vary.

The advantage of rotation matrices however is, that you can multiply them to get a single matrix that does all the rotations at once.

Which is also true for quaternions. They have the same properties, being associative and obeying the distributive property, but do not form a commutative ring. But again, this is just the math, and not that helpful in this case.

@SpyerGame said in How to rotate object in 3D space about its axis:

Cause Qtransform is in C++ and there is not in qml and how to use it

I'm pretty sure there's a Transform QML element that's "related" to the QTransform class ... like this one ...

SpyerGame

Thanks, yes it is, but I think use fromAxesAndAngles but I don't know how to work each vector3d of axes. In other words if each of a,b & c in Qt.vector3d(a,b,c) !
I know that Qt.vector3d(1,0,0) is X axis and so on but I don't know what is it Qt.vector3d(.54,.1,0) ?
My desired rotation around X,Y & Z of object like this:
alt text