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Messages - Benjamin_F

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[Max] Feature Requests / Re: The most wanted feature?
« on: 2022-04-28, 18:44:11 »
Since Corona is mainly used for interior renderings, and there are fabrics in each of them, I would like to suggest considering the introduction of a separate shader for fabrics.
I work quite closely with fabric in all its variations and came to the conclusion that corona render cannot currently provide an effective tool for rendering it realistically, and introducing sheen and velvet attributes in coronamtl will not fix the problem. Geopattern can partially solve the issue but we dont have it.

In 2017 viscorbel created a thread but did not receive any comments from the development team.
There he mentioned the ThunderLoom plugin that uses the Irawan shading model (introduced in 2012) with pattern determination with WIF files to correctly recreate the reflectivity of individual fabric strands, with the correct anisotropy without using falloff fake approach.
Now i can create any texture in substance designer but cannot use it properly to explain my render engine what i want from him))
Basically, we need something like CoronaHairMtl but with the ability to apply it to regular surfaces, imitating the thread pattern by using texture maps or wif files (moreover, the basic set of patterns can be included in the Corona material library), with separate fuzzines setting, ability to use bump and normal maps for initial mesh, not for individual hair strand only, both for adding wrinkles and for imitating thread volume.

Since I have tried a huge variety of approaches to creating fabric, I have a large pool of ideas, especially concerning UI of this feature. I hope the developers will pay attention to this issue and in the future when someone sees a beautiful fabric on the renders he will say "oh, probably it was rendered with Corona"


+1 vote for this

[Max] I need help! / Re: Corona Renderer for 3ds Max Help
« on: 2019-11-04, 03:02:24 »
I think the helpdesk is a big useless mess what I try to avoid 99% of the time. I only open helpdesk if it really necessary, usually because of some strange error messages.

To find some structured information about how Corona works is just not possible in this form and (dis)organization. Hard to read with a very cluttered page layout, formatting.

I could say no offense and don't take it personally but I won't. I'm sure you are caring about educating your users, and I just wanted to give some feedback that it's going in a very bad direction. I'm pretty sure you can do better than this.

Please refer to the Arnold user guide or Vray.

I also attached some screenshots for easy visual comparison. :)

And if you have 2019+ max, then there's OSL UVW node. It seems there's more solutions to this problem, than anyone could have think of :]

Do you know if there are performance drawbacks to very OSL usage in Corona ?

In all of my test with any OSL node, render speed is degraded by 50%, and crushed my dreams. :(
Even with one OSL color value node.(2019)
I guess I didn't tested it under 2020, yet.
Corona 5 might have fixed?

+ 1 for values and levels.

I would love to see a feature that automatically adjusts black level to the lowest pixel value, also white level to the highest pixel value. It would be very useful for remapping.

RGB and individual RGB channels maybe?

[Max] Feature Requests / Re: Vexus with Corona Renderer
« on: 2019-08-13, 15:20:46 »


check out Prism, developed by Mill Film. It's a good reference for speed, responsiveness, under sampling even in very heavy scenes.

I really hope that the max team will fully implement USD into Max, and Hydra will be supported too.

Can we expect a hotfix for version 4? October is far away.

Changing colors with Corona color picker is pretty much slower than with the default color picker.
Both during IR and in the Material editor.

Check out the screen record.

Pokoy, I did some tests with Arnold with the same circumstances like in Corona. There are some differences(more than I thought), but not much between legacy off or on.
These are not average numbers, only 1 render.

Simple color in the standardSurface : 113.691s, 100%
OSL color value in the diffuse slot, Legacy off: 118.862s, 104.54%
OSL color value in the diffuse slot, Legacy on: 119.832s, 105.40%
OSL 6 nodes, Legacy on: 123.533s, 108.65%
OSL 6 nodes, Legacy ff: 123.444s, 108.57%

The color node in a diffuse channel - is this with Corona? Does performance drop that much? Compared to a CoronaColor map or something else?
I' not sure what you mean, but I compared to a single CoronaColor connected to CoronaMtl diffuse. Than I just connected 1 or more nodes between the CoronaColor and the material, with the default settings.
Is it an answer to your question?

Thanks Ondra, good news.
Did you guys checked other nodes?  E.g. 6*UVW randomizer 18% drop, 6*CoronaMultiMap 25% drop, 6*CoronaMix 30% drop. (default settings)

Would you mind share some thoughts about the OSL slowdown problem?

Yeah, I also know about the mixing shading context thing. But I think it's just partly true here. You break the OSL optimization chain if you insert a non OSL node between them, into an input slot of an OSL node.
If your non OSL nodes are at the and of the chain it's okay. But I'm really a beginner with OSL yet.

You can see in the render message window, it will show this error message:
"A non OSL shader (Map #3 (CoronaColorCorrect)) was connected to the input 'Input_map' of an OSL shader (Map #5 (OSL: Tweak (color))).
This can lead to suboptimal performance, and will be less portable. Try to use only OSL shaders."

Checked the legacy thing in Arnold, but the documentation talks about the legacy built in Max maps, not the new OSL implementation. Only mentioning viewport - render differences.
I guess, it's written before the 2019.3 update. Zap Andersson demoing this in his video. Arnold doc:

Loosing 10M rays/s from 31M, one third of the "computation power" only because one OSL color value node is connected to the diffuse, doesn't seems to be a realistic scenario in any way.

I also wanted to check this in Vray, but I only have it under 2018 and there is no OSL.

I badly want to use OSL in production.

The best, ideal thing would be just simply forget about most of the corona map nodes, and rewrite them in OSL, voila you can use them in any DCC which supports OSL.
Users could write them so the Corona team wouldn't need to waste it's time to do these.

Of course I know many things, even UI controls are not supported officially by osl. And C4D is not support it, if I'm correct.


short story: I wanted to start to implement OSL maps into our shading pipeline to live a long, relaxed life, but I did some very simple tests. After I noticed massive slowdowns with even just an OSL color node, I started to test different corona maps too, to find out if this problem only connected to OSL or not.
It's seems Corona maps can heavily affect render times, even if they are basically do nothing at all.

How I did the tests:
- almost all of the maps was "turned off", no default parameters are changed, I expected that they should act as a pass-thru node or just output a single color. Connected to the diffuse slot.
- with bitmaps
- with disable shading(render only masks) and CShading Source(RAW)Color: diffuse, bitmap sampling turned off, with nearest-neighbor and others in the bitmap sampling(because of the OSL text. loader)
- with environment maps: single bacgkround color(no map), single coronaColor node, coronaBitmapHDRI in a very simple leftover of an interior scene
- in the diffuse, glossiness and reflection color slots of CoronaMtl

Recreate the problem:

Sample scenes are attached(2019), materials and nodes are in SME. Everything is super simple.

You can test to render the scene with only connect a CoronaColor to the diffuse and compare it with adding a CoronaColorCorrect after the color, don't change the defaults(does nothing in this state), render time is doubled.
I tested it with many possible combinations, with many nodes like CoronaColor+someNode, connected to diffuse or env.

- When I used a CoronaColor(white)+CoronaColorCorrect in the env. slot and in the diffuse, rendertime is tripled.
- If there is a Corona ColorCorrect only in the environment map, no less slowdown.
- It affects the diffuse and reflection color but not the glossy or bump channel

Attached some test renders, I hope the filenames are understandable.
- - a very simple leftover of an interior scene, model is shit
- - disabled shading, CShading_SourceColor, you need to select the plane before render(blowup auto select region is on)

Basically almost every corona map affects render time more or less, I think much more than it could be considered acceptable. Did some simple tests in Arnold, no render time increases like these.
CoronaColorCorrect is the worst one of all the corona maps. It can slowdown rendering 2-3 times. General OSL nodes 2 times slowdown, TextureLoader is the slowest OSL.

Ohh, by the way, multiplied CoronaCC train is multiplying slowdown, however OSL nodes are not, it seems they are only triggering something sensitive stuff. Check the last picture, fun.
I was able to do 30 x longer render times with a few CoronaColorCorrect nodes doing nothing. :)

I pretty  hope you will fix this in a hotfix together with the OSL slowdowns.

Please let me know if something is unclear or I wrote some bullshit in this f****g too long post.
Corona 4.1, Max 2019.3(2020 too), multiple dualXeon machines, win10

ps.: I found this old topic about OSL trace() call, I guess you know it's fixed in 2020(OSL APT for 3rd party renderer dev include OSL trace() function call).

[Max] Resolved Bugs / Re: Corona4 EXCEPTION_ACCESS_VIOLATION
« on: 2019-06-20, 19:01:56 »
Thanks Rowan.

[Max] Resolved Bugs / Corona4 EXCEPTION_ACCESS_VIOLATION
« on: 2019-06-19, 19:59:25 »

I'm using ProjectManager. Since Corona 4 thumbnails are rendered fine but not saved. Only with Corona 4.
This is the error message in the listener:

— ########################################################################
— Address: 0x511f04fd; nCode: 0x00000000C0000005
— Desc: EXCEPTION_ACCESS_VIOLATION The thread tried to read from or write to a virtual address for which it does not have the appropriate access.
— Read of Address: 0x0000000000000000
— ########################################################################

I reported this problem on the ProjectManager forum and this is what Alexander Kramer wrote:
"This is a bug in Corona 4
Corona 4 generates the exception on rendering start with simple maxscript command
bm = render vfb:false
You can report about this bug to developers."

[Max] Feature Requests / Re: tiled exr tx textures
« on: 2019-06-05, 11:21:56 »
A big thumbs up for this!

With a lot of 100-300Mb textures, life is getting really hard.
Would be great to directly support .tx files.


Thanks, I saw it and I will definitely check your script.
Anyway it would be a nice thing if the official(is it?) converter would have an Fstorm option too, but only if it not keeps the devs away from much more important stuffs.

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