Alpha and scene clear color while taking a screenshot

Questions
1

Hello, I’m trying to create a screenshot of my scene which contains alpha blended materials. Normally my Babylon scene has a clear color of Color4(1,1,1,1). But I need to have my object separate in the image so I can overlay it later on top of other images.

Now when I take a screenshot the objects with alpha below 1, it gets faded when I set the clear color to a transparent Color4(1,1,1,0). Even though my default clear color is white normally and it visually looks the same. when I overlay this screenshot with the transparent clear color on top of for example a white background it doesn’t obtain the same color either as the opaque clear color screenshot.

Is it possible to get a screenshot with the same “opacity” as a scene with an opaque clear color?

A scene to demonstrate what I mean (change the indicated lines):

EDIT:
Setting it to Color4(0,0,0,0) seems to fix it. This makes little sense to me however, can someone explain this behaviour?

2

@Evgeni_Popov

3

(0,0,0,0) is the right color because of the alpha mode used, which is ALPHA_COMBINED (note that your code is doing mat.alphaMode = BABYLON.PBRMaterial.MATERIAL_ALPHABLEND, which is wrong, it should be mat.alphaMode = BABYLON.Constants.ALPHA_COMBINE, but it happens that MATERIAL_ALPHABLEND==ALPHA_COMBINE==2!).

ALPHA_COMBINE is computing the final color as SRC_ALPHA * SRC_COLOR + (1 - SRC_ALPHA) * DEST_COLOR

So, if you clear with (0,0,0,0), DEST_COLOR = (0,0,0) and the final color will only depend on SRC_COLOR. If you clear with (1,1,1,0), the final color will be a mix (depending on source alpha) of the source color and white.

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