Heh, I really don't want to turn this thread into a "renderer vs renderer" thread but I would like to share my opinion as well. So to that end, I'll just throw a couple of things that I think Corona should do better and other renderers typically do better :)
- UVW transforms
We currently have super limited ways of doing UVW transforms and I totally think this is a Maxon oversight (resolved in R20 with the UVW node) but it is what it is. All of the other renderers have resolved this ages ago because you can't rely on the projector shader alone - It works locally and so each map you'd want to change you'd need to change independently. Imagine having a lot of maps and each was being driven by its own project shader - you scale one map you need and it works fine but scale multiple maps and you need to go in each one manually. Further complicating things, you perhaps change the mapping and ... All of the sudden, you need to go in each and every map in all of your materials.
What is even funkier is that the project shader is currently bugged so besides using a Layer -> Transform to scale maps, there virtually isn't a way to do this properly with Corona which makes it really hard to use for ... Well, anything complex really :D
- Opacity maps
Yep, I know we need to use Corona Bitmaps to increase the performance of materials with opacity maps. Still, it's buggy and wonky yet is one of the most crucial things a renderer can do.
So, typically you can stack materials in the object manager so that you can do things like decals and labels. You got a base material and then a material with an opacity map on top. Stacking itself works fine but it tanks performance ~10x. I went from renders taking 30 seconds to taking 1 hour.
Sure, you can apply a Corona bitmap to the opacity slot of that top material but it is again, unreliable. Sometimes it completely breaks material stacking in the object manager and you get a weird result out of it. Sometimes it appears to be working though.
Now, one could use a Corona layered material but that leads right into my other point about...
- Map previews
I don't think there is a renderer out there that doesn't have a feature that lets you preview the maps you are working on either in the viewport or in the IR. So take the layered material from the above - you have a base material and a label material on top. You used an opacity mask for the label material but you have _no idea_ how it maps onto the object.
Sure, you can use the final beauty IR but that only works on simpler objects and in simpler scenes.
What I typically end up doing is creating a normal c4d material, place that opacity map in the diffuse slot, apply it to the material and then map it to the object that way - because I can see it in the viewport.
Now sure, its a workaround and it isn't that time consuming but combine this with the fact that its troublesome to scale multiple maps in the first place (UVW transforms) and it becomes seriously tedious to do these types of things.
A simpler example would be doing a wood shader. You apply a dirty glossiness map on top of the wood glossiness map and now all of the sudden you don't know how that dirtiness map scales.
- IR reliability
I'm such a fan of the IR that Corona has, its crazy. I still remember the early 3ds Max alphas and it being one of the first CPU renderers with an IR option - certainly the most feature full at the time. Still, I often find the C4D version to be unreliable. It starts resetting randomly when you have Xpresso tags in your scenes, it sometimes randomly forgets to do Bump maps properly until you restart it, material overrides can still be buggy and don't update properly... It has actually happened to me that I was working on an object with the IR being turned on, 20 minutes later I do a final render and it looks -completely- different. I get it, sometimes it won't update properly but I find other renderers to be much more reliable in this regard.
- Node Edtior
So this one is a major pet peeve of mine because I just don't think it is ready for prime time yet. Anytime I've used it for more than 10 minutes I've gotten corrupted materials in the IR (random colors pop up) or corrupted materials in the nodal editor. I simply don't feel confident using it because if I spend 20 minutes working on a shader and it then bugs out beyond repair (nodes literally get lost), I just can't bill that to the client. I haven't used it with team rendering yet but I'm still hearing that its not totally reliable there either.
So yeah, I wanted to throw these out there because personally (well, and some of my colleagues and clients) these are the things that keep making me use other renderers. Quite honestly, for projects that require complex material making and where I want to be effective during work (reliable features) I actually prefer renderers that crash often (khm khm :P ) :P
I'm a really big fan of the Corona renderer, I was here since the beginning of the 3ds Max plugin - I'm really excited about all the stuff that is happening to the renderer. Still, with that said, I do want to be critical and hopefully help improve the product. I know the devs don't have it easy and even Maxon could do a better job with some of the above and offer native tools and options but let's face it - that just isn't the case right now. That said, what is important to note is that most other renderers have resolved these things internally - they are basic things that a renderer needs to have imho.
So yeah, I hope this doesn't come off as too negative or something. I just took 20 minutes off a busy day to write it all up so that it hopefully helps someone :) I'd also like to point out that the users that I interact with share similar sentiments although they aren't hanging around these parts :)
edit: oh and... Multi instances ;)
