Search in
Sort by:

Question Status:

Search help

  • Simple searches use one or more words. Separate the words with spaces (cat dog) to search cat,dog or both. Separate the words with plus signs (cat +dog) to search for items that may contain cat but must contain dog.
  • You can further refine your search on the search results page, where you can search by keywords, author, topic. These can be combined with each other. Examples
    • cat dog --matches anything with cat,dog or both
    • cat +dog --searches for cat +dog where dog is a mandatory term
    • cat -dog -- searches for cat excluding any result containing dog
    • [cats] —will restrict your search to results with topic named "cats"
    • [cats] [dogs] —will restrict your search to results with both topics, "cats", and "dogs"

Office Holiday

Epic Games' offices will be on holiday from June 22nd to July 7th. During this period support will be limited. Our offices will reopen on Monday, July 8th. 

Tangents vs Normals vs Binormals?

I understand why i need Normals. But i dont understand why do i need Tangents and Binormals? And how they related to Normals...

Why Normals are all Symmetric and every Surface has own Normal, but there are only 2 Tangents and they are not Symmetric, but surfaces are still totally Symmetric... i dont understand why i need tangents, and also binormals.

alt text alt text

Product Version: Not Selected
normals.png (172.9 kB)
tangents.png (155.7 kB)
more ▼

asked May 30 '14 at 07:41 PM in Rendering

avatar image

1.1k 118 143 371

(comments are locked)
10|2000 characters needed characters left
Viewable by all users

1 answer: sort voted first

Oh, after looking at Ball's tangents/normals/binormals i become understand, that Tangents is something like X direction for texture UVs, and Binormals is Y direction for texture UVs.

Ball have for some vertexes 2 tangents/2 binormals because its actually not 1 vertex, its a 2 vertexes which connecting different UV parts, this 2 vertexes seems 1 Normal, but actually there are 2 Normals as well.

I hope i did understand well.

alt text

ball.png (268.7 kB)
more ▼

answered May 30 '14 at 08:15 PM

avatar image

1.1k 118 143 371

avatar image darkgaze Mar 27 '18 at 03:12 PM

Be careful about this, though. This is very confusing. When creating a shader, if you create the mesh yourself and then create a material/shader that changes the normal parameter, don't listen to that tangent space.

What the normal plug in a material expects is a typical tangent space: Z is normal, Y is bitangent, X is tangent (in the U direction), which is RIGHT-HANDED, and not compressed (values go from -1 to 1, not from 0 to 1, like you normally do in other softwares (normal maps look purple instead of dark blue).

After passing those values, internally, Unreal swaps Y for Z, changing it to a LEFT-HANDED space.

In fact you can test this by passing a (0,0,1) normal to a material. It will work as a normal vector to the surface. But when you see it's effect, it seems to be a (0,1,0) vector :-)

(comments are locked)
10|2000 characters needed characters left
Viewable by all users
Your answer
toggle preview:

Up to 5 attachments (including images) can be used with a maximum of 5.2 MB each and 5.2 MB total.

Follow this question

Once you sign in you will be able to subscribe for any updates here

Answers to this question