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"

Alpha in normal maps not working

I'm pretty sure this worked in UE3 and in UE4 it shows that a normal can have alpha with "Has Alpha Channel: True" but it is always just white. So I'm guessing this is a bug and not a limitation.

Product Version: UE 4.8
more ▼

asked Jul 04 '15 at 11:39 AM in Bug Reports

avatar image

945 104 147 201

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

1 answer: sort voted first

Hi Davision -

The Default Compression format for Normal Maps in UE4 is BC5 which does not retain Alpha information, hence the white value when you look at the Alpha Channel. You can adjust the Compression which you use on the Normal Maps to VectorDisplacementmap which will allow you to reallocate some bytes from the Red and Green Channels to generate an Alpha Channel with some minor loss of quality to the Normal map. You will also need to change the Texture Sample in the Material to use Linear Color as opposed to Normal Map.

I have put in a feature request to add the NormalMapAlpha compression that would allow you to keep the NormalMap compression (Probably forced to DXT5 and not BC5) and an alpha channel, for reference UE-18196.

Thank You

Eric Ketchum

more ▼

answered Jul 06 '15 at 04:15 PM

avatar image

Lovecraft_K ♦♦ STAFF
36.7k 702 260 735

avatar image 00k_ Aug 13 '16 at 11:40 PM

Was this issue ever resolved? It still seems like there's no way to have a normal map with alpha and using a vectordisplacement map is not realistic given it's uncompressed.

(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