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Freemorpheme

Exporting to FBX for Substance - Phongs

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Hey kids, 

 

I am trying to get a low and high poly mesh out of C4D and into Substance and am running into trouble baking the meshes. I get these horrible seams. I am led to believe it's something to do with edge breaks and phong shading in the high poly mesh, buuuut when I export to FBX from C4D it appears to ignore the phong shading you make?

 

So I set my Phong angle to 60 degrees to make a nice smooth edge. I export to FBX and then test the FBX by reimporting to C4D - the Phong tag has reset to 40 degrees. I dont even know if this will fix my issue, but I need to test it to try and isolate it. 

 

I tried exporting to different flavours of FBX - turning Normals on and off etc. Nothing. 

 

If anyone has any general tips on exporting meshes out to Substance then do chip in.

 

Thanks

 

 

lines.JPG

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  • Here is the mesh if anyone is a Substance Painter user. I have been exporting this out with the SDS turned off, then again with it active and ticked in the settings.

    testy.c4d

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    There's a couple of rules you need to adhere to to get optimal bakes when doing normalmaps:

     

    • Every Hard Edge (Phong Break) needs to be a UV-Break as well.
    • Every UV-Break needs to be a Hard Edge (Phong Break) as well.
    • I would not recommend to rely on the Phong angle on the mesh. I've had many issues with that in the past. Instead you'll have to set your hard edges by hand. This is the normal workflow anyways for high to low normalmap baking.
    • Leave enough space between the UV islands

     

    Normalmap baking can be very hard to get right as there's soooo much stuff you have to look out for. If you need more in-detail help I'd recommend heading over to polycount.com. There's tons of great game asset artists there that can help with the process and tons of great tutorials on the topic. One of the best ones which helped me a lot is this one here: https://polycount.com/discussion/146667/a-practical-guide-on-normal-mapping-for-games

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  • 1 hour ago, DasFrodo said:

    couple of rules you need to adhere to

     

    Thanks - would you mind breaking it down a tiny bit more for me? On my mesh, I had hoped to have one smooth series of bevelled edges from top to bottom - is that not a reality? Should each bevel be a phong break? 

     

    phongs.thumb.jpg.5bcd703d34a7759f3e6c1827c349a1d6.jpg

     

    Your first two bullet points are the same, but the other way around. Is that an intentional '1st Rule of Fight Club' emphasis, or should the second one say something different? And I dont read you right in thinking a UV break is a physical break of the unwrapped UVS, do I? As in I would separate these UVs along the bevels? I spent ages keeping them together to get good seams.

     

    How much padding is enough padding? Is this OK?

     

    1845177163_ScreenShot2019-08-01at10_22_08.thumb.png.2b42a56a60a12f62229b55b828bfdf92.png

     

    Thanks

     

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    Quote

    Your first two bullet points are the same, but the other way around. Is that an intentional '1st Rule of Fight Club' emphasis, or should the second one say something different?

     

    This is intentional. What I meant by this is that if you do a UV-Split while Unwrapping you NEED to have a Phong-Break along the same edges. The other way around, as soon as you have a Phong-Break, you NEED to have a UV-Split along the same edges. Keep in mind this is ONLY for the low-poly model. The high poly model can be as detailed as you want and doesn't need any breaks or even UV-Mapping. You can model whatever you want there.

     

    Quote

    Thanks - would you mind breaking it down a tiny bit more for me? On my mesh, I had hoped to have one smooth series of bevelled edges from top to bottom - is that not a reality? Should each bevel be a phong break? 

     

    There is no general rule of thumb really. The only thing you probably want to always adhere to is having as little gradient as possible in your normals. As much as possible of your normalmap should have the classic normalmap blue-ish :)

     

    TangentSpace.png

     

    The reason for that is that a normalmap should not be overly used to correct smoothing errors due to weird phong breaks. As I said, normal maps are a complex topic and there's no way I can just break it down for you. You'll have to read up about it, sorry.

     

    Quote

    How much padding is enough padding? Is this OK?

     

    Depends on the resolution, really. I think as long as you have ~5 pixels space between every island it should be fine.

     

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  • 1 hour ago, DasFrodo said:

    have to set your hard edges by hand.

     

    Thanks for your patience. One more thing- when you say set hard edges by hand, is this Mesh - Normals - Unbreak Phong edges?

     

    A part of the problem I am having is that the method for doing these things is unclear. The document at Polycount you linked was very educational, but only in theory. Actually what tools and methods to achieve the goals is still frustratingly opaque.

     

    There is only one UV break on my whole mesh - right now I have no idea whether to try and remove it, or add more elsewhere.

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    You don't have only one UV-Break on your mesh. Every edge-loop that is not connected to another polygon is a UV-Break. So if your UV-Layout has two islands, you have two UV-Breaks. I attached a document to show you what I mean by the stuff above.

     

    We have three UV-Islands in that scene. The top of the cylinder, the bottom and the sides. As the sides cannot possibly be unwrapped with only a cut between the top and the bottom of the cylinder, we have a phong break at the exact edge where the island is split up as well. This is the principle you'll have to use on your entire model to get clean normals.

     

    uvbreak.thumb.PNG.cd4fd9fac3508e4e3435a05885efe232.PNG

     

    When talking about Edge-Breaks, we are talking about breaking phong shading. The opposite is unbreaking phong shading, with gives the edge that smoothed appearance.

     

    If you have any more questions, just ask. I know this topic is very confusing but once you wrap your head around it it's very logical and clear. It's just hard to explain :lol:

     

    Normalmap_Phong_UV-Break.c4d

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  • 3 minutes ago, DasFrodo said:

    You don't have only one UV-Break on your mesh.

     

    Balls, I meant I have only one Phong Break, or so the Phong Break selection tool is telling me. There is no Phong Break or UV break where I am getting the odd seams on my mesh. 

     

    When you said 'set hard edges by hand'  - did you mean selecting the edge and unbreaking the phong shading with the command under Normals?

     

    Thx

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    No, I mean selecting the edges that correspond to the UV-Breaks and using the "Break Phong" command. "Unbreak Phong" smoothes the edge, break breaks the edge and you get hard shading.  That's what you want.

     

    I'd also recommend setting your Phong Angle on your Phon Tag to 360° as you do not want any automatic phong breaks when you deal with normal maps.

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    Here, this should be clearer. I created a quick setup for you with exported models for your own testing. Hope this helps!

    I don't have Substance Painter though, so the normal map in this example comes from substance designer. There might be differences between the bakers.

     

     

    Normal Bake.7z

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    1 minute ago, DasFrodo said:

    . I created a quick setup for you

     

    Bless you, I would be jumping out of the window now were it not for helpful souls like you.

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    No worries! That's what we're all here for, isn't it?

    If you have any further questions or issues feel free to ask. I'll keep this thread open.

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