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    Reflections in Glass

    Hey All,

    I'm having a terrible time getting reflections in my glass material. I'm rendering a car making use of the most recent Automotive shading pack. The only lighting in the scene is the HDR backdrop
    Everything else reflects nicely (see attached), but even using the Automotive material presets, I cant get any reflections in the windows. I know its possible (https://www.youtube.com/watch?v=ZBq5_ZhQPN4)
    but I seem to be missing something. Any ideas would be greatly appreciated.
    Thanks!




    #2
    Reflection captures and surface shader model on glass.

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      #3
      I'm assuming the reflection captures will only look good wit static camera and objects?

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        #4
        Originally posted by grendel2k View Post
        I'm assuming the reflection captures will only look good wit static camera and objects?
        Works fine on dynamic objects and camera (thats the entire point.) Just dont expect it to be perfect.

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          #5
          Isn't there a ray-traced solution? In Epics video above, you can see the glass reflections are just as accurate and crisp as the paint, I don't believe this was done with a reflection capture

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            #6
            Originally posted by grendel2k View Post
            Isn't there a ray-traced solution? In Epics video above, you can see the glass reflections are just as accurate and crisp as the paint, I don't believe this was done with a reflection capture
            Sorry for slow response, ue4 isnt an offline renderer (and will never ever be), the best you will get is realtime raytracing, or surface shading (as mentioned) with SSR on. Also, you can increase the resolution of reflection captures in project settings.

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              #7
              There is a raytraced solution. But for that, if you create a completely new glass material, you not only have to switch your Blend-Mode from "Opaque" to "Translucent", you also have to scroll down and switch to the category "Translucency" -> Lighting Mode and there switch from "Volumetric NonDirectional" to "Surface ForwardShading". This gives you access to the opacity node, metallic, and roughness node in the material.
              Then just create a parameter or a fresnel, hook it up to the opacity, and set it to something other than zero, so that the material is not 100% transparent. The more opaque your material gets, the more reflections you will get. Just balance things out with the opaque slider and metallic, if you want the type of metallic coated sunglasses or windshields.

              With a PostProcess, make sure, that your Translucency is also handled with Raytracing (default it´s set to "Raster" instead of raytracing, unlike reflections). Then it should work and you get something like this.

              Click image for larger version  Name:	Raytracing-Glass.jpg Views:	0 Size:	536.4 KB ID:	1774708

              I have not placed any reflection captures in that scene. However, i have raised that reflection resolution to 2048, just in case, it is still required for something.

              Edit: And don´t forget (like i did ^.^) to also connect a parameter to the specular input, since in raytracing, the Specular input is used to set the refraction. But since the specular input just accepts 0 to1, and the most people would use IOR values, you would need to include a tiny converter (just some more nodes) for IOR to Specular conversion. This was mentioned in the forum here somewhere, just cannot find it atm.

              Translucency Index of Refraction (IOR)


              When setting up and using refraction for ray tracing, the Specular material input is used to control the index of refraction, or IOR, in your translucent materials. The ray tracing features of Unreal Engine follows the Disney BRDF model whereby specular and IOR values are coupled and cannot be defined independently.
              https://docs.unrealengine.com/en-US/...ing/index.html
              Last edited by Suthriel; 06-12-2020, 01:55 AM.

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