Interface object in Ortho view

This topic has 9 replies, 3 voices, and was last updated 6 minutes ago by David Duperron.

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2024-11-13 at 10:51 am #78692

David Duperron
Customer

Hi there!
I’ve got some interface objects (a North indicator) parented to an Orthographic camera, that I want to display on the top left corner.
I use the “fit to camera edge” feature in Blender that appears when an object is parented to a camera.
The object is then visible in this corner, but its scale varies when zooming in or out!
How can I keep it to a constant size??
Thanks for the help!

David

2024-11-13 at 3:35 pm #78698

xeon
Customer

The indicator should be:
1. Parented to the ortho camera
2. Have its parent inverse cleared
3. Then repositioned to desired location if needed

Xeon
Route 66 Digital
Interactive Solutions - https://www.r66d.com
Tutorials - https://www.xeons3dlab.com

2024-11-13 at 4:30 pm #78699

David Duperron
Customer

Thanks Xeon, I will try again, even if I think I did all this the first time… will keep you posted!

2024-11-13 at 11:30 pm #78709

xeon
Customer

Even if you parented the object to the camera…it should stay locked to the camera regardless of zoom and movement of the camera. So it shouldn’t scale….but when you use Fit to Edge the clearing of the Clear Parent Inverse will make it behave correctly.

Xeon
Route 66 Digital
Interactive Solutions - https://www.r66d.com
Tutorials - https://www.xeons3dlab.com

2024-11-14 at 8:03 am #78737

David Duperron
Customer

Hi Xeon,
Tried it several times but it does not work for me… when I parent an object to an ortho camera, and use the “fit to camera” option, the object scales like the main scene when I zoom in/out, no matter what…
With perspective cameras it works without any issue, but not with ortho cameras… would be curious to have the developpers point of view about that?? @yuri?

2024-11-14 at 8:13 am #78739

kdv
Participant

David Duperron wrote:

With perspective cameras it works without any issue

because perspective cameras instead of zooming just move along their Y axis back an forth. on the contrary, ortho cameras are using real zooming.

Puzzles and JS coding. Fast and expensive.

If you don’t see the meaning in something it primarily means that you just don’t see it but not the absence of the meaning at all.

2024-11-14 at 9:24 am #78741

David Duperron
Customer

Hi @kdv! Yes I noticed this difference. But I don’t know how to counteract the zoom effect on the object that is parented to the camera.
I thought I could play on the scale of the object, that would be “linked” to the ortho zoom factor, but I cannot make it work…
I guess I will have to fall back to an HTML overlay when in Ortho mode.

2024-11-14 at 9:27 am #78742
kdv
Participant
smth like this can do the trick
```
  function setObjectScale(mesh, factor) {
    if (app.camera.isOrthographicCamera)
      factor = ((app.camera.top - app.camera.bottom) / app.camera.zoom) / factor;
    else
      factor = (mesh.position.distanceTo(app.camera.position) * Math.tan(Math.PI * app.camera.fov / 360) * 2) / factor;
    mesh.scale.set(1, 1, 1).multiplyScalar(factor);
  }
```
Puzzles and JS coding. Fast and expensive.

If you don’t see the meaning in something it primarily means that you just don’t see it but not the absence of the meaning at all.
2024-11-14 at 3:14 pm #78751

David Duperron
Customer

Hi @kdv!
Yes I did not think about this function! You’re right we are almost there. I can keep the object to a constant scale relative to the viewport with this, but the offset from the left edge (and top edge) of the window is also scaled. I need to find where I can adjust this distance… if this is possible…

2024-11-14 at 3:49 pm #78757

David Duperron
Customer

Maybe I can play on the “offset” value of the constraint applied to the object with a modified function.
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