Alpha Mask issue with some objects

[rohit.gonsalves_]

Hello.

Please find attached simple Project created in 2.6.1.1. As we use this projects for Augmented reality we need to overlay 3D things onto Video. For this stuff we Make Common->Background Alpha = 0 and make environment-> Sky = 0.

With this settings if I use the rendering from unigine in our engine. We have black edges and shadows all around the specific objects. It makes things worst. 

To regenerate this issue just run the above project and grab the texture. The same issue happens for us. This issue is with many objects we have used. Particularly, ObjectVolumeProj and Particles which are used to create smoke. 

You can test the grab I have taken in GBufferTest\data\screenshots\frame_0000.tga.

In our last visit to Unigine it was asked to change rendering orders and alpha blend options. But it never worked. Now it is clear that the alpha mask was not written correctly at this moment.

Please suggest how to solve this issue?

regards,

Rohit

GBufferTest.zip

[silent]

Hi Rohit,

Not sure how should I grab the texture, but doing the screenshot (video_grab command) I get correct results. There is seems no additional code available for texture grabbing that you are using. Could you please provide an additional sources (if any) that will do the grab logic?

Thanks!

[rohit.gonsalves_]

Hi silent,

Can you please post the screenshot.

I just used the video grabber built in the editor..

Rohit

[silent]

Hi Rohit,

With video grabber tool indeed I can see that artifacts. Well, technically speaking that's not the real artifacts due to the bugs or some weird driver issue. It's just how alpha is blended with other textures.

The issue here is mainly related to how the transparent objects are rendered: they are using additional forward rendering pipeline on top of deferred, so it's sometimes impossible to correctly mix them.

We will think how we can improve this behavior in the future SDK updates.

Thank you for the feedback! 

[silent]

A small update for the test scene you sent us: there is no alpha channel in default texture for volumetric object, so it blends as it should - there is no bug. If you will replace default texture with a new one with alpha there will be no such artifacts.

Also, I've tried to use particles and it seems that they are working OK (they have alpha in texture).

Please, keep in mind that if you need to create a gradient for correct blending you have to create it only in Alpha channel (not in RGB). For example, default particles texture in SDK is not really correct - it has gradients in RGB and in Alpha channel (but it will be enough to have them only in Alpha channel).

Thanks!

[rohit.gonsalves_]

Thanks Silent..

Wow it was such a simple thing. Actually it happens with all objects where default texture don't have alpha channel.

We need this kind of support for rendering Virtual objects on Live Video Streams for mixed reality.

Rohit