What is the purpose of the Opacity channel in this example??

[ShynnSup]

Hi everyone!

I have been reading up on some Corona documentation but I can't understand why in some cases I see material set ups like this:



What is the purpose of the Opacity channel in this case? What would go wrong if none is used? Most of the times I don't use it for my leaf textures...

Also seen here:

[burnin]

most often, geo that uses such shader is just a poly rectangle...

best you do your homework, personal experience is priceless ;)

[ShynnSup]

most often, geo that uses such shader is just a poly rectangle...

best you do your homework, personal experience is priceless ;)

What?

[Nejc Kilar]

In that leaf example the geometry of the leaf itself is just a simple plane mesh - so just a basic rectangular shape. Then, because that plane is properly UV mapped, the leaf bitmap texture fits onto it perfectly but... That still doesn't solve the fact that the geometry is a simple plane and the leaf is a more complex shape than that, right?

Well, you can then just use the opacity map to "cut" the non-leafy parts of that plane. It beats modeling it (time wise) plus there's less actual polygons to render.

Hope that helps :)

[BigAl3D]

@ShynnSup It would help to know your level of knowledge with C4D, Corona and video production in general so people helping you don't assume you know more than you do, or seem to "talk down" to you. If you know about video production, but are new to 3D, then change the word Opacity with Alpha Channel. An alpha channel in Premiere or After Effects (and all others) allows you to "cut" shapes our of an adjacent layer. Since C4D standard material uses Alpha and Transparency, I was originally confused with Corona using the term Opacity instead of Alpha and Translucency instead of Transparency.

Darker area in the Opacity (Alpha) slot hide or cut away unwanted areas of a material leaving the lighter pixels to determine the visible shape. As Nejc Kilar mentioned, this is a method to reduce polygons and vertex points, but only visually. Technically, each leaf is still a square, but you only see the leaf shape. Unless you get very close to the tree, it still looks OK.

[ShynnSup]

Thank you both @Nejc Kilar and @BigAl3D.

I get it now. Basically A vs B

No Opacity


With Opacity


The reason I was not sure about its function is because I really never had the need to use it, just always used a plain texture, like here:

So this texture has no black borders, so it occupies the whole geometry, and no opacity is needed. Unless I would want even more detail, which I don't.

@ShynnSup It would help to know your level of knowledge with C4D, Corona and video production in general so people helping you don't assume you know more than you do, or seem to "talk down" to you.

I don't think it has to do with that... asking someone to do their 'homework' is plain rude, specially when it is clear form my OP that I have been watching tutorials. But never mind, ignore and continue.

Thanks

[BigAl3D]

Not meant to be rude at all. In fact, I didn't want to be rude by assuming you have little experience when you actually do. Watching a bunch of tutorials is good, but does not always equate to years of using the software.

In your last example, that looks great. You wouldn't need an Opacity channel if your geometry is the shape that you need. Good luck.