Normal map layering bug.

[A'nW]

Hi there. I believe I have found a bug. I am using your custom Blender 2.61.4 build with V-ray 2 and your latest script version 156d1c7. I think that having multiple layers of normal maps doesn't work! I am not 100% sure if this is a bug... but I sure hope so. Not being able to layer nor maps would be rather bad. I would upload a test .blend and picture if I could, but I am unable to upload stuff right now. Fortunately it is very easy to reproduce. Just have a material with two normal map textures, each affecting the bump/normal channel. You will see that the bottom (of the texture list) layer completely overrides the top layer. With gray-scale bump maps it makes little difference because blending modes like Add, Multiply, etc, work as excepted. With normal maps, though, none of the the different blending modes seem to work really. If I am missing something please tell me! Hope to hear from you soon, and as always, thanks for your great work on this addon Andrey!

[FakeAce]

Re: Normal map layering bug.

We've also experienced this & found a workaround in the meantime.
In this link you can find a method to combine normal maps in photoshop. You can make an action in photshop to automate the process.

Here's the link: http://www.rodgreen.com/?p=4

[A'nW]

Re: Normal map layering bug.

Hey there FakeAce, thanks for the reply. That was a nice explanation of normal maps and how to combine them! It definitely will help in certain cases. Unfortunately, you also can't layer a procedural bump map over an image normal map. There is no fix for that I don't think. Thanks for the help though. I think that this bug really needs fixed though.

[A'nW]

Re: Normal map layering bug.

Here is a test .blend for what I was talking about. Made in the custom VrayBlender 2.61.4 build with the latest script. It is almost the default scene. It is just a plane with a default material and three packed textures. The first two are normal map image textures and the third is a procedural bump map. The top two (the bottom two in the list) are disabled. Enable them to see that they just completely override the effect of the textures that are higher in the list. Hope it helps to squash a bug. If it is not a bug let me know!
Here is the link:NormalMapBugTest.

[A'nW]

Re: Normal map layering bug.

You know, I don't want to bug, but this really is a problem. Has anyone looked at the file I put up?

[bdancer]

Re: Normal map layering bug.

Fix it git, test please =)

[A'nW]

Re: Normal map layering bug.

Hi! Thanks for the quick reply! I hope I didn't sound to demanding , I know that you receive little compensation for your great work on this.
Anyway, It is better. Unfortunately I can't say fixed. It is better in that it now lets you layer 1 bump over 1 normal map. If you have more than 1 of either type, though, It will only use the top (lowest in the list) one of each kind.
For instance, if they are all activated:
(This is supposed to be the texture list in Blender)

Normal Map <- Ignored/No effect
Normal Map <-Used
Bump <-Ignored/No effect
Bump <-Used

The used bump layers correctly over the used normal map though!

I hope this helps, and thanks again for your work on this! If you need a .blend I'll get one for you. I just didn't have time to upload one right now when I saw your reply.

[bdancer]

Re: Normal map layering bug.

Basically textures are blended correctly, seems just like such blending doesn't provide desired result. I could try to to add different normal shaders for each texture, but this will take more time...

[A'nW]

Re: Normal map layering bug.

Sorry for the delay in replying, for some reason I couldn't access the forum for a couple of days. I had this prepared very soon after you made your reply.
Anyway, hopefully this will clear up everything that I am talking about, as I intend to explain what I am thinking exactly. First, I will show how I wish Vray was working, I will show this with BI. It , in my opinion, does this part correctly.
In the picture below you can see how Blender treats and applies normal and bump maps. It is very logical and intuitive I think.

1. Enable NormalMap1.[/*:m:10iy6gxg]
2. Enable a NormalMap2. As you can see it simply layers right over the first.[/*:m:10iy6gxg]
3. Enable a procedural bump map. Again, it simply layers right over the normal maps. Very logical, everything just layers as expected over each other in order[/*:m:10iy6gxg]

[attachment=1:10iy6gxg]BlenderNor.png[/attachment:10iy6gxg]
Here is the .blend for this if you want to see it: Blender normal mapping.. You can enable/disable what you want and it just works. The bumps layer as expected.

Now in V-Ray.

1. Enable NormalMap1, works as expected.[/*:m:10iy6gxg]
2. Enable NormalMap2, now things go wrong. We completely lose the affect of NormalMap1. All we can see is NormalMap2.[/*:m:10iy6gxg]
3. Enable a procedural bump map. This works now. It layers it effect over that of NormalMap2. NormalMap1, of course, still has no affect.[/*:m:10iy6gxg]
4. Enable a second procedural bump map. The same thing that happens to the normal maps happens here. We lose the affect of the first procedural bump map. We still have the affect of NormalMap2 though. It is as if it takes the one top texture from both the bump and normal maps and layers just those two.[/*:m:10iy6gxg]

[attachment=0:10iy6gxg]VrayNor.jpg[/attachment:10iy6gxg]
Here is the .blend for this: V-Ray normal map bug test


Obviously, the pictures might be kind of hard to decipher. That is why I have also attached the .blends for each picture. I also hope this clears up what I have been trying to say. Also, I don't know if this is an exporter bug/limitation or a V-Ray problem. I hope you can fix this though if it is in the exporter. I also don't really understand your last post, because, as I showed, the layering in V-Ray doesn't work beyond one bump and one normal map.

Thanks for putting up with me on this!

[bdancer]

Re: Normal map layering bug.

I also don't really understand your last post, because, as I showed, the layering in V-Ray doesn't work beyond one bump and one normal map.

Try to set different blend modes for normal textures - the result will be different, but what we really want is not to blend textures, but to stack brdf shaders.

Now it works like:
2. Bump brdf -- blend(map1+map2)
1. Bump brdf (normal) -- blend(map3+map4)
0. Material brdf

And I need to rewrite this to:
4. Bump brdf -- map2
3. Bump brdf -- map1
2. Bump brdf (normal) -- map4
1. Bump brdf (normal) -- map3
0. Material brdf

And it will be pretty tricky to rewrite current shaders export function this way. Hope to find time on weekend.

[A'nW]

Re: Normal map layering bug.

Ahhh ok, I finally see what is going on. Thanks for the explanation. I would like to see this done, but definitely take your time. I'm just glad that your doing this at all! Now that I see it is not a "bug" I don't mind waiting a while for this.