Gun Modelling Shading Issue

[ilkyal]

Hey guys. I am modelling a gun and I’m getting the following shading issues that you can see in the screenshots:

Methods I tried:

• Triple checked: No ngons or triangles are found. The whole model is made out of quads.
• Merge by distance: Can not find anything to merge. (Removed 0 vertices)
• Recalculate normals: Does not change anything.
• Auto smooth is already activated. (Set to 30) (Changing the values does not fix it)

I am only using bevel and mirror modifier. No subsurf is activated. Activating it does not make the issues go away.

[RSEhlers]

Check the junctions of your Ridges and body…There are many HOTLINES…Where the cut intersects with a mesh line…( mainly happens when using Boolean Difference…

It can be adjusted and a lot of times removed by using Shift + V and sliding the line away from the hot Junction

[ilkyal]

Hey. Thank you for your reply. Unfortunately, moving edges from that location is not possible considering that it changes the shape of that part of the model. I am hearing about the term “hotline” for the first time. I made a quick Google and Youtube search but can not find anything about it. If possible, can you guide me with where I can find more information about this subject?

[RSEhlers]

It is used alot in Hardsurface modeling in Boxcutter and Hard-ops…
Even if you didn’t use a boolean for the ridges the effect is still the same…

@chippwalters and @masterxeon1001 use the term in a lot of their Beginner Videos

https://www.youtube.com/c/ChippWalters/videos

https://www.youtube.com/channel/UCOCDPQGB3HBq54lDyTWde_A

[etn249]

What happens if you put a “weighted normal” modifier on the model?

That modifier is used to improve the normals on low poly models, especially if they are bevelled, like this:

I have had similar shading get fixed by that modifier (though it will depend if the topology is actually clean or if there is a real problem).

[ilkyal]

If I add that modifier, I get the following results:

Without the modifier:

With the modifier:

If I uploaded the project file, could you take a look at it and tell me if there is something weird going on with the topology?

[etn249]

It looks like it did improve some parts at least, but maybe not everything.

If I had a look at the model, I could probably tell, yes.

[ilkyal]

Thank you so much for your help. I really appreciate you taking your time and trying to help me out. Here is the file:

secondary_gun.blend (914.4 KB)

[etn249]

First thing, activate “harden normals” on the bevel modifier. It does something similar to the weighted normals, but it affects only the bevel itself. This will already remove a bunch of shading issues.

The harsh line on top is caused by the edge loops right above and below the glitch. Having multiple edge loops in close proximity will compress the shading over a short distance and create a pinching effect. This effect becomes increasingly strong the more curvy a surface is.

What’s happening is that you are modeling at such a low resolution that you run into a fundamental limitation of 3D graphics: smooth shading depends on the shape of the polygons, so having few of them will always lead to a flawed shading.
In this image, I also spaced the polygons a bit more evenly for nicer shading for this very reason.

I also found a problem at the front of the gun:

and here is the fix:

In some places, you can see a break in the shading:

This can be improved by sliding the polygons apart, so the transition is more gradual.

At that point, your shading should only really be a problem if the object is perfectly reflective, so try looking at it without the shiny matcap, as it shows the slightest problem that you may not even see with the final material.

And if you truly need a super low-poly model to have perfect shading, the way to do that would be to create a second, subdividable version of the model and use that to bake a normal map.