Incorrect reflections of point lights (forward rendering)

Hi, Epic team. I have some problems with reflections of light source in forward rendering mode (engine version 4.15.1). The fact is that reflections of point lights is correct only in certain directions. Perhaps this is somehow connected with the axes coordinate. This is especially noticeable when roughness of materials is equal to zero. At the same time, in certain sides, the reflections are not visible, while from the opposite sides they exist. It is looks like bug. But maybe I just do not know any settings. I will be very glad to hear any information about this.


This is expected due to how the Forward Renderer handles specularity and culling Reflection Captures and Lights to a frustum-space grid. Each pixel in the forward pass then iterates over the lights and Reflection Captures affecting it, sharing the material with them.

To prove to you that the forward render can account for the proper reflections, you need to set the Material to Translucent and set the Lighting Mode to Surface ForwardShading. Then input a 1.0 for the opacity and you should get an identical result. This is an expensive lighting mode, and depending on what you are trying to do, it might be okay to use it is small amounts. Let me know if you have further questions.

Thank you,

Thanks for your answer. I understand well that the technology of forward rendering is not yet ready. It takes a lot of refinement, because the technology was not originally in the engine. But the variant described by you does not suit me. For obvious reasons I guess. Currently, I work a game VR project, in which beautiful graphics are important. I need realistic materials and lighting. A lot of realistic materials. But at the same time I need good performance. Forward rendering allows to achieve this, but shortcomings with reflections hinder the tuning of materials. I have to make materials is mat to look more or less good. But some have to shine. Unfortunable I can’t make materials like this. This makes me very sad, especially since for example in Unity there are no such problems with reflections in forward mode. Thus it turns out that in the forward mode of UE4 it is very difficult to achieve the desired result for me. Possible options are two: switch on deferred mode, or wait of fix this problem by engine developers. I would like to know are you planning to fix incorrect reflections of point lights for opaque materials? Maybe in 4.17 version? Any information about this will be useful to me.

These are just the current limitations of the Forward Renderer. We are aware and working to improve upon them. I am not sure what you are referring to because your examples and explanations are fairly vague, and you have not provided any concrete examples on what you are actually seeing. It is very possible you could be doing things incorrectly, because I know we do support correct parallax reflections in the forward renderer. You can also use planar reflections to get really high quality results.



Planar reflections are not a solution in this case, because they have the same problems with reflections of point lights. Actually, it’s not about reflecting light sources as such, but rather in the correctness of the visualization of materials in general. I will try to explain on a concrete example. For example, I made the material of the stone wall and it looks realistic. The wall correctly reflects light and glare on the surface look good (pic 1). But if I turn around and look at the opposite wall, which has the same material, it already looks like it was doused with oil (pic 2). The material on the opposite side does not look right. So I just can not customize the material in such a way that it looks equally from all sides. Thus, at the present time it is impossible to make correct materials in forward mode of UE4, which have at least some visible specularity. I hope that now you understand the importance of this problem. An early correction of this shortcoming is necessary for those who do VR projects in realistic graphics. I very much ask you to apply all possibilities and all the influence for an early resolution of this problem.


So I decided to go ahead and enter this as a bug, as although I believe it could be a limitation of the Forward Renderer and how it handles reflections, the difference between both renderers remains pretty drastic. You can track the bug by following the link I have provided below.


As of now you have couple options that I see, you can return to the deferred renderer or try to reduce the light’s radius so they are not overlapping so you can better control the nearest surfaces reflections.


Daniel Wright said, that this bug fixed in 4.16 version. I checked and can confirm - now reflections of point lights is correct. You can see more here: Incorrect reflections of point lights (forward rendering) - Feedback & Requests - Epic Developer Community Forums