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. 

Transparency in Render Target 2D shows up black


I'm trying to render a 3d widget onto a 2d texture, using a render target 2d asset created from within the editor and the FWidgetRenderer class at runtime, from within C++. But any transparency in the widget shows up as black in the resulting texture (I'm using this in the context of stereo layers for VR).

Is there anything I need to do to enable transparency when rendering or displaying the rendered texture?


I just did some tests and it seams the deal is that I cannot set the clear color of the texture to "Transparent" from within the editor. That is, if in C++ I grab a reference to the texture I created in the editor and at runtime do Texture->ClearColor = FLinearColor::Transparent; then from that point onwards transparency does work.

So I guess the question is how does one set the clear color of a render target texture from within the editor?

Product Version: UE 4.14
more ▼

asked Jan 10 '17 at 06:36 PM in Rendering

avatar image

157 16 19 35

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

3 answers: sort voted first

According to the 4.14 release notes:

The "SceneColor (HDR) in RGB, Inv Opacity in A" option can be used to render objects with translucency into a texture which can then be alpha-blended over a scene or widget blueprint.

Not sure if that's any help. It's under the "New: Scene Capture Improvements on Mobile" section of the release notes for 4.14.

more ▼

answered Jan 10 '17 at 08:11 PM

avatar image

2.1k 67 84 77

avatar image saldavonschwartz Jan 10 '17 at 08:59 PM

@CleanCut Thanks for the info. I'll check it out. However, I updated my question since it looks like it's about the texture's clear color; I don't know how to set it to transparent from within the editor (I only know how to from C++).

avatar image CleanCut Jan 11 '17 at 12:33 AM

Maybe they renamed ClearColor to ChromaKeyColor in blueprints?

alt text

avatar image RHoath Mar 02 '17 at 03:34 PM

ChromaKeyColor is a separate property.

You could try exposing FLinearColor ClearColor in TextureRenderTarget2D.h?

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

You can use "Clear Render Target 2D" in blueprint: https://puu.sh/us8HR/c2732b52e0.jpg I'm using this to fix blackness on StereoLayer when rendering a 2D UMG .

more ▼

answered Mar 03 '17 at 09:27 AM

avatar image

38 1 4 7

avatar image Jonas_Molgaard Aug 31 '17 at 08:08 AM

@DeathUman the picture you posted is missing. Can you repost your solution by chance? I got the same problem with blackness on my StereoLayer using a color (0,0,0,1) if i call clear with (0,0,0,0) then all subsequent draws are not showing up, even with a material that has an alpha map.


avatar image Jonas_Molgaard Aug 31 '17 at 08:24 AM

This is my setup btw... it works in PIE, but once i package it, it turns black. Im on 4.17 btw. alt text

capture.png (391.3 kB)
avatar image S-ed Aug 20 '18 at 11:11 PM

@DeathUman This is the reason why I hate people linking images for 3rd party sites. -_-

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

This works for me

     Instructions_RT = NewObject<UCanvasRenderTarget2D>(this);
     Instructions_RT->InitAutoFormat(ViewSize.X / 2, ViewSize.Y);
     Instructions_RT->ClearColor = FLinearColor(0.0f, 0.0f, 0.0f, 0.0f);

more ▼

answered Jan 02 '18 at 09:59 AM

avatar image

56 4 4

(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