Problems with "glass" properties in Pbrt v4 about freecad-render HOT 24 CLOSED

Hello,
Could you please post your FreeCAD project, so that I can reproduce? Thanks!

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Hello, with the new version of render I see something changed about the power of area lights. Now it needs to reduce a factor 100 (!) to obtain the some effect than before. Have you any feedback of that?
Regards

as4_molla_scaric3.zip

from freecad-render.

About area lights power: Yes, I had to rework them. Indeed, I harmonized the different units used in the code, in order to export to the renders in standard and similar units from one renderer to another (meters, watts...). This implied a work of harmonization of the units, including the power units. For pbrt, this translates well into a factor of 100, as shown in the following commit: 31f3683

Thanks for your file, I will try to look at it in the next days...

from freecad-render.

Clear now, many thanks.

from freecad-render.

If I remember correctly you were working on a new material tool, a huge task. May I help in any way ? Searching data, testing something... I'm afraid, my python is basic.

from freecad-render.

Yes, I had a plan to create a library of rendering materials... and it's actually created, although it's modestly only 9 materials at this point. However, I think they do allow for the most common renders: plastics, metals, carpaint...
To create more materials though, I will need to add an advanced feature, which is Texture management. It's a new and heavy development I'm planning for 2022.
Your help can be welcome, there is not only Python code to do: your testing and feedback is much valuable.
Also, if you feel like writing documentation, don't hesitate!

from freecad-render.

Your part ("Body") must be applied the glass material, if you want it to be rendered as glass!
Use 'Appy material' menu action to do so, and it should work:

I also attach the model, if you want to check:

as4_molla_scaric3.v2.FCStd.zip

from freecad-render.

I applied last update of render wb and assembly4 and executing "render" command on your file I get a funny result in attachment: it's the rendering resulting png.
In addition even assigned the proper material to the body of my original file the aspect remains opaque.
Something fails somewhere. About some help I'll try to do what in my capabilties.

from freecad-render.

Argh! They silently removed the "tint" parameter of glass (Dielectric) material, see mmp/pbrt-v4#182. I run an older version of pbrt than yours, so I didn't notice.
I'll have a look at that in the next few days.
(Again, it shows pbrt is just an illustration for a book, not a general purpose renderer...)

from freecad-render.

I see, pity. I'm not chained to pbrt but last two years I tried to compile appleseed (which has no updates from long time) and luxcore which depends from Intel peculiar libraries, both unsuccessfully. Please suggest me a real alternative linux compatible if available. Regards

from freecad-render.

Just to try something different I easily compiled the following libraries:
https://tsubo164.github.io/Fujiyama-Docs/index.html
http://www.horde3d.org/home.html
https://www.cycles-renderer.org/
I'd like your comments about.
Regards

from freecad-render.

Cycles (standalone) is supported! It's usually a nightmare to compile, but if you succeeded, it's an excellent choice.
The others I don't know.
By the way, what distro do you use?

from freecad-render.

I compiled cycles in while, luxcore is an endless nightmare! Anyway please have a look to the screenshots, from cycles, in attachment: it seems to me an unusual behavior with that small windows in addition and a strange "ballet" of canvas output.


As distro I'm using Ubuntu Mate 20.04.

from freecad-render.

Render creates a new window each time you launch a rendering ("Rendering result", see the tabs). You may have a better view if you a maximize it.

from freecad-render.

Anyway, very nice renderings!

from freecad-render.

Thanks. Be patient but of course was generated a new window a rendering but with the new render wb appears also a new win red marked. This is new and uncontrolled until rendering tab was erased. Is this correct?

Ah, cycles is a flash but not so accurate as pbrt; I'll try to more accurate test with different materials/lights, etc.
If I would try to add some material where have I to start for?

from freecad-render.

I believe there was a problem. Do you remember my big assembly as first try on pbrt? Using cycles it doesn't recognizes area lights and the rendering canvas, done a render and leave it, is populated of the buffer/win of the assy components but not selectable. I'm afraid of but it's new for me.

from freecad-render.

with the new render wb appears also a new win red marked.

You get a new window each time you execute a rendering. In your screenshot, you must have run 2 renderings, so you get 2 windows, as stated in the tabs below (look for "rendering result"). It just appears that one window is maximized (the one that displays the full picture), the other is minimized (the one you marked in red). To me, there is no malfunction. However, I may add an action to menu in order to control maximization/minimization.
Please note it's an old feature, I just recently enhanced the image display widget in it (see the context menu, for instance, or the scrollbars in minimized window) but that's all.

the rendering canvas, done a render and leave it, is populated of the buffer/win of the assy components but not selectable

It's because the "Rendering result" window is on top of all the other windows and maximized, so logically it does not allow you to interact with other windows through itself. But you can see the other windows through "Rendering result" as its background is transparent: maybe a bit frustrating, I understand.
Hence 2 remarks:

• You can still switch to other windows using tabs bar, underneath. Or you can reorganize your windows using "Tile" in FreeCAD "Windows" menu.
• Background transparency for "Rendering result" window is misleading and undesirable, so I must work on it. Just a question however, to help me: did you specifically ask for window background transparency, somewhere in settings?

If I would try to add some material where have I to start for?

I'm not sure to understand: where do you want to add materials? In your model, or in Render materials library?

Using cycles it doesn't recognizes area lights

Well, it should! Can you please increase the power of your area lights? Try very high values, and just let me know if they are still invisible... Thanks!

cycles is a flash but not so accurate as pbrt

I think we're going to start a renderer war 😄

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In addition, please note I removed 'tint' parameter from glass material for Pbrt (b831038)

from freecad-render.

Update:
I understood what was wrong with the windows: it was related to the style sheet. I made a fix (#166). Can you tell me if it works correctly from your point of view?
My other questions (area lights, materials) still open: do not hesitate to bring me feedback!

from freecad-render.

Great touch. Fix #166 rewind the tape and now the background is clean, for my preference. Below a screenshot before fixing:

and after fixing:

Your suspect were right about arealights in cycles: for a sensitive results it needs a power of 6000.0, used for previous shot.
At the same power, below the shot from pbrt, that now without "tint" runs:

and finally a shot from pbrt area power of 6.0:

even too much!
Many thanks, the model attached.
Mount.zip

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Forgotten, sorry: about adding material I was thinking to Render material library if impossible to keeps a "local' lib.

from freecad-render.

Lights powers balancing between renderers is really a hassle, I'm at a loss with that: it's very hard to get the same result between all engines. I introduced magic numbers into the code, but it appears not really efficient. Perhaps one day, I'll add some user coefficients in projects parameters...
For materials, your help will be welcome but, beforehand, I have to add some support for textures. It will take a few weeks I think...

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If you don't mind, I may close this issue at this stage (please reopen if you consider there is a need).

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