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Syle Devin

Weird Lighting on Mesh

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So I've been noticing these weird light issues with my mesh ever since I started making mesh for SL. I thought I would finally post my problem. I am sure that it has something to do with how low poly my meshes are but if that is the case then I don't know what to do because I don't want to add prims just for lighting. 


Has anyone had this problem before? The mesh itself is flat on the top except for the 45 degree angle but the lighting is making the smaller right side brighter. I can fix the light issue by adding more vertices to the round edge or making the top flat with a hard edge, both of which I do not want to do. Adding more vertices would add more prim and making the top flat changes the whole style of the design.

Weird Lighting 1.1.jpg




















Has anyone had this problem before? I've tried to reset up the mesh to no avail without adding more vertices.


Edit: I also know this has something to do with the smooth shading but smooth shading has it's uses. Is there a way to use smooth shading in SL with low vertices and not have any issues?

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Yeah .. thats an issue with the Gouraud Shading.

The little problem you have here is, that you have a tiny triangle in that corner.

Try to change this triangle into an quad and the problem is gone.
 Well of course it is a bit effort to rearrange the faces then. But it pays off

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Hi. I've been looking at this the last couple of days. Agree that smooth can cause problems; most of us have been there. And tris are apparently not good to use unless you have a purpose and I don't know enough to HAVE a purpose so avoid them.

My only thought would be to try dissolving the quads on that top face that are doing their shadow dance for you. Have no idea if that would help but it might. ngons can cause big problems too with shadows but you probably know that.

Oh, and I think you might want to do some testing on your builds. That comment " Adding more vertices would add more prim and making the top flat changes the whole style of the design." is not necessarily true. I have very complex (well for me) builds that come in at .5 LI. Look at the upload costs and play with the LODs to get that land impact down. This doesn't look like a huge object from the screenshot. There is no reason that you need to see all those details all the way across the sim. :D.

Just a thought.

AH, and now as I reread this I see that you WANT that crease to show, and the top isn't supposed to be flat? Maybe we need more info on what lighting you are talking about.



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With Smoothing you pretty much control how the normals of the faces are interpreted. So of course it can be of great use.

I.e.. You can create a very sharp looking edge with a break in a smoothing group (normal's smoothing not breaking over this corner /break and due to that creating a very sharp optical break) without adding more edgeloops.

But always weigh what solution you want to go for. Smoothing groups reduce the all over usage of Edgeloops and thus additional faces. But they do create more memory and render-impact in an in game environment. This is due to the fact that every UV seam, every smoothing group border etc has to 'separate' the vertices - thus creating duplicates. When being used very excessive with too many UV seams and too many smoothing groups you kind of negate the effect of sparing more faces by adding numerous amounts of vertice data. And vertices count is more important then the tris' count. (http://wiki.polycount.com/PolygonCount )

Non of the 3D modeling suits can actually show you how much 'in game' vertices your model would have. There are some scripts for Maya and 3DS that do such a calculation. But that really shouldn't be needed with such a rather low poly model.

Generally i do not only consider Landimpact when thinking about optimization. Its a matter of the all over content in such an environment and the quality of content you want to create. Unfortunately the landimpact (as the above answers already mentioned) is rather a very vague value and does not really display the all over quality or heavyness of a model.

Also I would never have SL generate the normals while doing the upload this also can cause troubles and unwanted / not controllable results.

In certain when it comes to triangles versus quads. Quads are just something a modeler tries to keep to the very end of his creation state. Due to them making the model more conclusive and working better with subdivision, edgeflow, and creating the all over topology of the model etc. As soon as a model gets into rendering or an in game environment all your graphic card sees is just triangles and nothing else.
So if you can't avoid to have some triangles in your model just go the full way and convert quads to tris at the end to achieve a more evenly spread normals behavior. The vertice count will almost not change when doing this because they share vertices at the end of each quad or tris. So this doesn't matter. 

And if you have a model mainly build of quads also for the final outcome/product then try to stay on quads to avoid such optical breaks in the normals orientation. Or put them in spots where they are almost not noticeable.

Cheers! Code

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