Factorio Forums

In this FFF, it's mentioned that:

posila wrote:particles below 2% opacity don't really seem to add anything to the final picture, so we can safely not draw those to get little extra boost.

I seem to have run afoul of this threshold in one of my effects textures, since it has non-zero colour values in zero-alpha areas of the image. What would normally be drawn additively is instead optimised away to be entirely transparent.

Is there any way to disable this optimisation for a specific sprite or animation? At the moment I'm just clamping the alpha value to 0.025 so it doesn't get discarded.

I don't think that is the problem. The optimization is per trivial-smoke particle, not per pixel. Smoke has defined some fade out animation in the prototype, and if result of that animation is 2% or less, entire particle is not drawn.

Images are premultiplied on loading, so that will destroy your non-zero color values. You can set premul_alpha = false, on sprite definitions that you want to preserve as is.

Oh hey!

premul_alpha is what I found first, and turned it off because I know what my alpha and colour values should be. The result is mostly what I'd expect, but a lot of pixels missing. I'm quite certain that it's a result of some sort of thresholding because when I increase then minimum alpha from zero, then all the pixels render. Might there be something in the shader? I'm not using any tint at the moment.

Can you share a mod that would demonstrate the issue?

Also ... the pixels might have been cropped out as cropping checks only alpha pixels, try to add to the sprite definitions following

Thanks, turning off cropping fixed the issue. I guess my other solution is better if I'm trying to keep overdraw down though, right?

In 0.17.15 cropping will check all channels are zero not just alpha.

Fantastic, thanks!

posila wrote: ↑

Sun Mar 17, 2019 7:37 pm

In 0.17.15 cropping will check all channels are zero not just alpha.

It means that we need black alpha borders, not just zero alpha?

darkfrei wrote: ↑

Mon Mar 18, 2019 8:23 am

It means that we need black alpha borders, not just zero alpha?

If you use premul_alpha = false, then yes. Otherwise cropping will have the same result as before.

posila wrote: ↑

Sun Mar 17, 2019 7:37 pm

In 0.17.15 cropping will check all channels are zero not just alpha.

I didn't see any mention of this in the release notes, and in my tests I'm still seeing pixels with non-zero colour being cropped. Did the change perhaps get missed?

The change did is in 0.17.15. I don't understand why "no-crop" would work, while not working with cropping enabled since 0.17.15. Can you share a mod that would demonstrate the issue?

Here is a mod which shows two test sprites. The source images are identical, but one has no-crop.
This is what it looks like in 0.17.14:



Oddly enough, in 0.17.22 both sprites are missing the zero alpha section.