Author Topic: corona bitmap shader  (Read 4264 times)

2017-01-04, 08:37:28

riccky

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in the last version, this function blurs the image texture in render

2017-01-04, 18:14:23
Reply #1

4b4

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yep +1 for this bug

2017-04-27, 09:39:38
Reply #2

houska

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Guys, I didn't notice any blurring in the corona bitmap shader. Can you elaborate more? Does the blurring still happen in the latest daily build version? If it does, when does the blurring happen?

2017-04-27, 10:37:54
Reply #3

riccky

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No more blurring with the new "daily" build version.
But I still notice some strange behaviour with the input function

2017-04-27, 12:37:59
Reply #4

houska

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Oh, cool. Glad to hear the blurring is fixed. Can you tell us more about the input function bug?

2017-04-27, 14:37:28
Reply #5

riccky

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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

2017-04-27, 15:00:08
Reply #6

houska

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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

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?

2017-04-27, 16:13:35
Reply #7

riccky

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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

2017-04-27, 17:25:10
Reply #8

houska

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

2017-04-27, 18:27:38
Reply #9

houska

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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!

2017-04-27, 18:55:08
Reply #10

riccky

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Thanks for explanation and support