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Impossible to add a LightFunction to any light? [latest UDK]

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    Impossible to add a LightFunction to any light? [latest UDK]

    I've been trying for a few hours now to get light functions working, but no matter what I try, it never lets me add one, to any lights whatsoever. I read that this was just because of a problem with the 2011 UDK's, so I just got the latest 2012 version, but the problem still persists.

    Heres what I'm doing... Where am I going wrong?:-

    -I've made a material, (just a flashing colour).

    -I've set it to be "used as LightFunction" in the material properties.

    -The texture is also going through the emissive channel.

    -I created a movable PointLight and unticked everything but the dynamic light options.

    -I select my light function material in the browser, then hit the blue arrow next to "LightFunction" (in the light properties) and press "New light function".

    Judging by what I've read and seen on some video tutorials, this is all you have to do, so I dont understand why it isn't working for me, on two different versions nearly a year apart.

    The only thing I can add, is that it tells me I have to set "Use Direct Lightmap" to False to use light functions, but that option is nowhere to be found...

    Does anybody know how to get LightFunctions working properly? If so, please help me out!

    #2
    Did you expand the light function section and linked to the material? Just clicking on the blue arrow doesn't do the trick. Without a material selected in the content browser it will auto-expand btw.
    [shot]http://udn.epicgames.com/Three/rsrc/Three/LightFunctions/LightFunctions_5_LightFunctionSet.jpg[/shot]

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      #3
      I haven't had any problems.

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        #4
        Yea I tried it with the material highlighted in the browser, but clicking "blue arrow" > "LightFunction" still doesn't do anything. Its just refusing to work.

        Is there any special options I've missed maybe? Do I have to have anything setup in a particular way (anything other than in the main post)?

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          #5
          Well I tested my function material (simple cloud shadows) on a movable point light and it works. The only caveat being that it is extremely distorted. Is it possible that your effect is so stretched or squashed that you aren't noticing it?
          Under the light function material slot you'll see some properties for scaling. Try setting them all to a value of one. This will make any distortion easier to notice. For me I had to increase the Y scaling by sixteen to get it looking normal. (I wound up with 1024, 16384, 1024)

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            #6
            The stretching issue you're describing is probably caused by not projecting the material as you would a cube map; a flat material would mean that four of your edges are projecting a one-pixel wide strip.

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              #7
              No its not stretching or scaling thats causing the problem. It wont even let me create the function in the first place, so I dont get to touch any of those options. I've seen it working, and I've managed to make it work in EXTREMELY rare cases, but 9 out of 10 of my maps wont let me add a light function to any light in the level whatsoever, regardless of the type of light, or how its configured (always with dynamic light options enabled of course!). Infact, the only map where functions ARE working, is the big medieval map where lightmass fails to build the light, every time, without fail, regardless of how I have the 'Importance volumes' or light-build options set.

              It just doesn't make any sense!

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                #8
                Bumping because I am having the EXACT same problem! Have my cloud material selected in the content browser, go to my dominant directional light properties, click the blue arrow, click on LightFunction and then... nothing. I can't get it to show the expanded options so I can't add my material. I have made sure my material has the option under "Mutually Exclusive Usage" ticked for 'Use as Light Function' and have my material setup exactly the way the tutorial below shows, but still, it won't let me add the function.

                http://forums.epicgames.com/threads/...ght-latest-UDK

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                  #9
                  Try changing the Blend mode to additive and the Lighting model to Unlit on your material.

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                    #10
                    Originally posted by DwunkenPenguin View Post
                    Try changing the Blend mode to additive and the Lighting model to Unlit on your material.
                    Hi, thanks for the reply, but the problem occurs when I click to add the lightfunction on the dominantdirectionallight object, it doesn't expand the menu. However, when I've tried it in a brand new level it allows me to setup a light function instantly with no problems. So I'm wondering if it's something in my WIP level that is causing the lightfunction to not work? I have adjusted the Lightmass settings to change the light colour to match that of the skybox static mesh I am using, not sure if that's relevant but would really liker to get this issue sorted. Thanks.

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