CODEWITHSUNDEEP
qttransparencyqt3d
Florian Blume
Florian Blume

Reputation: 3345

Qt3D transparency in offscreen renderer

I'm using Qt3D with a combination of this offscreen renderer and modified the framegraph to include a background image, like here.

Unfortunately, adding transparency to the objects drawn over the background image using QPhongAlphaMaterial only works unsatisfactorily.

This is th result:

this is the result

What you can't see here is that the whole circle part is actually transparent, i.e. the renderer wrote the transparency value of the object for the whole pixel instead of adding it transparently on top of the background.

This is what the rendered object looks like wihtout transparency:

enter image description here

And this is the background:

enter image description here

The framegraph has two branches: one for the backgroun image, which is processed first, and one for the objects. I added a QRenderStateSet for the objects that contains a QBlendEquation with the blend function set to add and a QBlendEquationArguments with source RGB and alpha set to 1, and destination RGB and alpha set to 1 minus source alpha.

Any ideas how to fix this problem?

(For anyone wondering, I took the images from the T-Less dataset and wrote a program to create ground-truth data for 6D pose estimation)

Upvotes: 3

Views: 727

Answers (1)

Florian Blume
Florian Blume

Reputation: 3345

Similarly to this question, the format of the texture that is being rendered to needs to be set to RGB8_UNorm and not RGBA8_UNorm, i.e. without the alpha channel.

Upvotes: 1

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