Wireframe node has no effect on bumpmap

Question

Im trying to use a wireframe node to influence the height of a bump node, but it dosn't seem to have any effect: Wireframe Bump

As you can see in the second image, the wireframe node is behaving properly because it influences the diffuse colour perfectly: Wireframe Diffuse

Any solutions to this problem?

J Sargent · Answer 1 · 2015-01-27T20:32:12.993

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There appears to be an issue with that node in conjunction with the Bump node. One solution that appears to work is using the Wireframe node in conjunction with a Normal Map node:

enter image description here

These nodes render a result like this:

enter image description here

Notice that these values can be inverted as well:

enter image description here

One word of warning thanks to @WChagrin:

I would say that that's almost certainly undefined behavior. The colored pixels in the normal map are supposed to represent unit vectors in tangent space. When the wireframe node outputs a value of 0, that's coerced into the vector <0, 0, 0>, which is not only non-unit, but non-normalizable. That is, trying to normalize it would require division by zero. Relying on this behavior is probably a Bad Idea™.

edited Jan 27 '15 at 20:32

answered Jan 27 '15 at 16:02

J Sargent

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...That shouldn't work – GiantCowFilms Jan 27 '15 at 16:04
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Seems to though . . . you can also influence the Strength value with similar results. – J Sargent Jan 27 '15 at 16:04
So do you think this is a bug? – Christy James Jan 27 '15 at 16:10
I didn't know you got yellow on a normal map, this is the strangest thing ever. – GiantCowFilms Jan 27 '15 at 16:13
It would appear so, the Wireframe node doesn't appear to output a value usable by the Bump node. – J Sargent Jan 27 '15 at 16:13
@GiantCowFilms You in Cycles? – J Sargent Jan 27 '15 at 16:14
@NoviceInDisguise No, I'm still right, the bump nodes dosen't support this strange yellow normal map that you've created. It also won't work with a brick texture – GiantCowFilms Jan 27 '15 at 16:15
@NoviceInDisguise I'm not that crazy! :P – GiantCowFilms Jan 27 '15 at 16:15
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@GiantCowFilms Meaning you are using Cycles? – J Sargent Jan 27 '15 at 16:16
I think we should take this discussion to chat. – J Sargent Jan 27 '15 at 16:18
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It does appear to be bug because I have baked the output from the wireframe node and it works perfectly. I can't recreate your yellow normal map (???), but I can confirm that the brick texture works fine, when the wireframe dosn't. I will go and log this on the bug tracker, Thanks for all your help guys. – Christy James Jan 27 '15 at 16:23
@ChristyJames So you copied my nodes exactly and it didn't work? – J Sargent Jan 27 '15 at 16:24
@ChristyJames I don't think it is a bug, if it isn't mind telling us what they have said – GiantCowFilms Jan 27 '15 at 16:24
@NoviceInDisguise Yep, your node setup worked just as in your pictures, but im trying to apply it to a complex mesh and the "Object Space" dosnt really give the right kind of results. – Christy James Jan 27 '15 at 16:45
@ChristyJames Did you come up with a better result or do you want me to whip one up? – J Sargent Jan 27 '15 at 16:47
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@NoviceInDisguise I made a workaround by baking the output of the wireframe node to an image file, and then using that image file to influence the height of the bump node, and that works fine for me. It would be interesting to find out why the wireframe node dosnt talk to the bump node though.... :) – Christy James Jan 27 '15 at 16:52
@ChristyJames You can add your workaround as an answer. Glad you found something that worked! I wondered if baking a texture might do the trick. Glad it is solved! – J Sargent Jan 27 '15 at 16:57
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I would say that that's almost certainly undefined behavior. The colored pixels in the normal map are supposed to represent unit vectors in tangent space. When the wireframe node outputs a value of 0, that's coerced into the vector <0, 0, 0>, which is not only non-unit, but non-normalizable. That is, trying to normalize it would require division by zero. Relying on this behavior is probably a Bad Idea™. – wchargin Jan 27 '15 at 17:49
@WChargin Excellent explanation! Mind if I add that to the answer? – J Sargent Jan 27 '15 at 18:19
@NoviceInDisguise please do. – wchargin Jan 27 '15 at 20:24
@WChargin I knew something was up A+ for spotting it :D – GiantCowFilms Feb 05 '15 at 18:38

score 2 · Answer 2 · answered Jan 27 '15 at 17:11

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This problem appears to be caused by the Wireframe node not talking to the Bump node properly. After a bit of disscussion and help from others in the comments I developed this workaround by baking the wireframe output to a file and using the file to influence the Bump node:

enter image description here

answered Jan 27 '15 at 17:11

Christy James

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Go ahead and accept your answer, it helps site stats – J Sargent Apr 14 '15 at 18:43

score 1 · Answer 3 · edited Apr 13 '17 at 12:57

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Why you can't see anything:

The reason (or at least one of) is due to a limitation of normal mapping. All that normal mapping can do is trick cycles into think the face is at a different angle. In your case, if you look at what you're trying to create from the top, all the faces are the same angle. In order for this to work, you need a bit of a slope.

Using displacement would work well, except in order to have enough geometry to displace, you will mess up the wire frame :/

The reason why the normal map node works, is that it supports some very unconventional normal maps. The bump map node is more particular about its output.

As far as Ray Mairlot's comment, a brick texture won't work form the bump map node either, I have tested it to check, there is only a slight edge visible along the slope that occurs between the bricks.

The bump and normal nodes are different:

The Normal Map node takes a color representation of a normal vector and turns it into a vector.

The bump nodes samples 2 areas on the height map and compares the angle the find the vector. since there is only black and white, it will only find 90 degree angles and therefore not show any edge.

Paraphrased From the wiki

edited Apr 13 '17 at 12:57

Community

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answered Jan 27 '15 at 15:51

GiantCowFilms

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Doesn't work on a sphere, I have a solution (I think) – J Sargent Jan 27 '15 at 15:57
@NoviceInDisguise Yes, it wouldn't, still no angle. the height map being converted needs to have a gradient in order to have an angle to give the illusion of height. – GiantCowFilms Jan 27 '15 at 15:58
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Then why can a black and white brick texture create a bump effect? – Ray Mairlot Jan 27 '15 at 16:01
I tried mixing RGB values with the Wireframe node, and then putting that into the Bump node, and that didn't work either. – J Sargent Jan 27 '15 at 16:03
I think the bump node is a bit fussier.... – GiantCowFilms Jan 27 '15 at 16:07
@GiantCowFilms Any ideas why? – J Sargent Jan 27 '15 at 16:09
@GiantCowFilms I have tried using the brick texture using the node setup in the question and it does work. I have also never had an issue of using only black and white bump maps without a 'slope'. – Ray Mairlot Jan 27 '15 at 16:31
@RayMairlot I protest... did you use only Black and White bricks? – GiantCowFilms Jan 27 '15 at 16:35
@GiantCowFilms http://www.pasteall.org/pic/show.php?id=82889 Pure black and white. – Ray Mairlot Jan 27 '15 at 16:40
@RayMairlot Precisely my point! that is not correct... there is a single line of at a 90 degree angle, with no height specification whats so ever! That is exactly what I said would happen. – GiantCowFilms Jan 27 '15 at 16:41
http://i.stack.imgur.com/TBbHX.png Look at this normal map. It is not at all going to produce accurate results! – GiantCowFilms Jan 27 '15 at 16:42
@GiantCowFilms Then I honestly have no idea what you are talking about and nor any idea why a brick texture would work and a wireframe wouldn't. – Ray Mairlot Jan 27 '15 at 16:43
The wire-frame did the same thing – GiantCowFilms Jan 27 '15 at 16:43
Let us continue this discussion in chat. – GiantCowFilms Jan 27 '15 at 16:44

Wireframe node has no effect on bumpmap

3 Answers3