[Viewer3D] Input bounding box (Meshing) & manual transformation (SfMTransform) thanks to a new 3D Gizmo

[julien-hdev]

Description

• Add a Transform Gizmo to control Qt3D entities inside the 3D Viewer (generic).
• Add an input Bounding Box inside the Meshing node to customize the area to reconstruct.
• Add a new transformation mode to SfMTransform using the Transform Gizmo.

Needs alicevision/AliceVision#846

Features list

• 3D Gizmo
  • Basic visual entity
  • Picking interaction & object transformations
  • Mouse handling orientation
  • Display on top of everything
  • Improve performances
  • Attach the Gizmo directly inside an object (using a special container entity)
  • Adjust manipulator sensitivity
• Bounding Box
  • New bounding box parameter in AliceVision
  • New bounding box parameter in Meshroom's Meshing node
  • Display BBox edges/faces
• SfMTransform
  • New transformation mode (manual) + new manualTransform parameter in AliceVision
  • New transformation mode (manual) + new manualTransform parameter in Meshroom's SfMTransform node
• Integrate Transform/BoundingBox input in the 3D Inspector

To do later: use BoundingBox struct instead of Hexah in AliceVision meshing process.

Transform Gizmo

Implementation remarks

The gizmo is entirely done with Qt3D in QML. To be able to get local transformations (and not global ones), we have to deal with matrix operations. Not all the methods/functions exist in QML, so we have to implement our own functions using PySide2 in Python.
The gizmo is made with meshes. Maybe it would be better to draw it on screen directly?

The controls are pretty similar to the Blender's gizmo ones. By the way, the visual is strongly inspired by the Blender 2.8+ gizmo.
It is quite user-friendly.

How to use

EntityWithGizmo

Inside Viewer3D.qml :

EntityWithGizmo {
    id: entityWithGizmoID
    sceneCameraController: cameraController // The id of the current DefaultCameraController
    frontLayerComponent: drawOnFront // The id of the Layer we want to draw on top of everything
    window: root // The id of the current FocusScope Item (acting as a window)

    // The entity
    Entity { components: [entityWithGizmoID.objectTransform, ...] } // The Transform of the Entity needs to be this attribute
}

Bounding Box

On the left, Meshing with default option. On the right, Meshing with the custom Bounding Box.

Implementation remarks

The Bounding Box is a simple Qt3D entity representing a box in the style of Blender. The transformations of this box are stored in the Meshing node. When we use the gizmo inside the 3D Viewer to adjust the box, the changes are sent to the Meshing node when we release the mouse button. Like this, we ensure data is stored in Python and not in QML. We can activate the use of the custom Bounding Box in the node and then adjust the parameters. In the 3D Inspector, on the right, we can show/hide the Bounding Box.

SfMTransform

To activate the gizmo, you must choose the manual mode inside method parameter. You can then adjust the parameters with the sliders and/or the gizmo.

Implementation remarks

When manual mode is set, the point cloud you see in the 3D Viewer is actually the input with a real-time Transform applied to it. Even when the node is computed, this is the transformed input which is displayed.
Fix #994

[natowi]

This will (partially) solve #616 & #617 & #744