[QGIS-Developer] GSoC QGIS 3D Improvement: Week 7 Report

[Martin Dobias]

Hi

On Mon, Jul 15, 2019 at 9:40 PM Ismail Sunni <imajimatika at gmail.com> wrote:

>  Nice screencast. Are billboards able to handle alpha/opacity channel for
>> a given raster?
>
>
> Do you mean the billboard is transparent and we can see the stuff behind
> it?
>
> Well, I am not in that level of understanding of this 3D rendering. But I
> can say it's not easy to do something transparent in the 3D world. Since we
> need to reconsider how it will be done (without transparency means we just
> ignore the covered surface of the 3D objects, while with transparency we
> need to know the order of the object). That's what I got from my discussion
> with Martin. *Please correct me if I am wrong Martin :)
>

For billboards that do not rectangular shape (a circle) yes that should be
possible and easy to support fully transparent pixels. For semi-transparent
images, there will be an issue, rendering output is not going to look good
without some special techniques because of how Z buffer works and because
objects would need to be always rendered back to front (from camera's view)
for alpha blending to be correct.

Cheers
Martin
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