Ahich is more efficient, cutout transparency or translucent transparencies?

[GalacticMuffin]

@Harcarik;556760

i am not that big expert so please verify from other sources but i believe cutout opacity si way more efficient/cheaper than translucency. if you want translucent like effect with cutout opacity mask use dither alpha node, it is surprisignly effective. hope it helps.

Definitely thanks for the info! ill check out the dither alpha node.

@jwatte;556772

Cut-out CAN be more efficient than translucency, for two reasons:

1. The graphics card may not have to read what’s below the pixel to calculate a blended value
2. The graphics card may be able to update the Z buffer in a way that makes early-Z testing work

The specifics of these two options depend a lot on the specific hardware you’re running on, AND on the scene.
For example, if nothing will generally be behind the clouds, the the early Z testing doesn’t matter, because there’s nothing to occlude.

The only way to know whether this matter for your hardware and your art is to set up realistic scenes and measure on realistic hardware.
If the clouds aren’t large, covering the screen with translucency, but instead the edges are smallish fringes on the screen, then the translucency will probably not be a problem.
Large transparent areas, especially with a lot of overdraw, will be a problem, especially on mid-to-low-end hardware, though.

hmm well here is a close up of the clouds, the player will never be able to get this close but this should paint a better idea for how I’m using the cutout:

going back to what you were saying about rendering things behind the cutout opacities, these clouds are composed of 4 meshes, 3 cutouts layered and one opaque int he center. considering what you have said about cutout layering, would this approach be perhaps less efficient than say clouds that are build using translucent planes like this?

I’ve since turned off the shadows that the cutout’s were casting and that has improved performance but I’m still debating whether i should use cutouts or translucency. I will need a lot of cloud cover on the screen at once whether that just means larger meshes or more of them, I still need to test that.