Chaos Corona for Cinema 4D > [C4D] Bug Reporting

corona bitmap shader

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riccky:
Same bitmaps is used for all spheres in the reflection and roughness channel
on the left :  "filter" function c4d is used. Top : 100% brightness. Bottom : 50% brightness
on the right :  "output" function is used. Top : 1 brightness. Bottom : 0.5 brightness

houska:

--- Quote from: riccky on 2017-04-27, 14:37:28 ---Same bitmaps is used for all spheres in the reflection and roughness channel
on the left :  "filter" function c4d is used. Top : 100% brightness. Bottom : 50% brightness
on the right :  "output" function is used. Top : 1 brightness. Bottom : 0.5 brightness

--- End quote ---

Ok, so the bottom left ball should be more glossy? By the way, I am a bit confused, because there is no roughness channel.

So you have a Corona Material with diffuse and reflection channel enabled, right?
And the reflection channel has a bitmap in the glossiness slot, filtered by the Corona Output shader?
And now the problem is that the results are inconsistent with what Cinema filter shader does and with what you'd expect?

riccky:
So you have a Corona Material with diffuse and reflection channel enabled, right?
yes
And the reflection channel has a bitmap in the glossiness slot, filtered by the Corona Output shader?
yes
And now the problem is that the results are inconsistent with what Cinema filter shader does and with what you'd expect?
yes. As the bitmap is pure white now because the brightness is at 1, the sphere must be (for me) with no roughness.
I give you the scene, just replace the hdri by one of yours
https://dl.dropboxusercontent.com/u/106066238/corona.rar

houska:
Thanks for the scene! A picture is worth thousand words, a scene is worth thousand pictures :-)

houska:
So I found it! The ball on the top right has the "Affected by Corona VFB tone mapping" unchecked, which means that the inverse tone-mapping operator is applied to the output shader. This is useful if you want your textures to be unaffected by tone mapping - e.g. for an environment map. But if you use the output shader in a map slot of something which does not get influenced by the tone-mapping (bump map, normal map, displacement map, glossiness map, IOR map, etc... basically any map that does not result in colors being rendered on the screen), only the inverse operation is applied and this results into the white being changed into grey...

Unfortunately, this is not shown in the shader preview, so you actually see white output and think everything is OK. Changing the preview to work consistently would not be so simple, so for now, I think we will add another sentence to the warning in the output shader.

In any way, thanks for catching this!

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