Hard edges on rounded caps

[RDH]

Hi there,

I am having an issue with rounding on caps of extruded objects, particularly with reflections. There are hard edges at the ends of the cap's curves instead of a smooth transition to the flat surfaces of the cap and the extrude. See here: https://drive.google.com/file/d/1LhDZ3Lb1aYOhfFAIBav594plz_vfcenM/view?usp=drive_link

If I uncheck the box "Break Phong Rounding" in the caps section, it smooths out those edges, but then my materials look all wonky like this: https://drive.google.com/file/d/1gIiVFlL7-IvjsEw8mt_om6YEuZRttg6p/view?usp=drive_link

What am I missing? This seems like it should be very simple.

-RH

[Dr. Sassi]

Hi RH,

The simple answer is that Polygons are based on Points, and to create those edges, they are calculated between points. These Edges are straight, no exception. This means the polygons are made of straight lines that build a frame.
Each Polygon has a Normal, which indicates a direction, which is often not true, as Polygons with more than three edges can be non-planar.
However, everyone knows that angle in and angle out for reflections are primarily based on these normals but also on the point's normals. See image. (Normals are these little lines in the image.)

Among all these norms is a softness calculated that a round object would have. While there is an option to break that calculation, the transition from a flat to a "round" impression is also based on that calculation. If the flat part has only one long Polygon before the "round" part starts, the softening "bleeds" into the flat part. The solution here is more segments (polygons) for the flat part and handles for critical objects, perhaps individually. Typically, the Phong option "Style" setting can help here.

Manual work is sometimes needed for precision or a smooth transition from a flat to a "rounded" surface.

If you create such an object in metal, the machine will give you that "edge", but if one hand grains sand and polishes the object, the transition will move into the flat part.

Please start the Redshift Renderview and move the time slide, as I have animated the Phong parameter. Compare with Subsurface Division on or off.
CV4_2025_drs_24_TXps_01.c4d

For any other question in the future, please consider that a project file tells me more than images, and please avoid the "request access" option. Thank you.

Cheers

[RDH]

Thank you for the explanation. So is there a "best practice" way to add more polygons to a cap?

My apologies for the "request access" on the images. I didn't realize permissions weren't set up for those.

On a side note, I tried uploading images directly here (there's an option to do so), however I kept getting an "image dimensions are too large" error message regardless of how small I made the images.

-RH

[Dr. Sassi]

Hi RH,

Thanks for your reply, not a problem with the access, but when I like to work on something, that blocks it.

The problem part is not the caps; it is the flat/straight part; here, you need to increase the segments/subdivisions so the influence is different.
The calculation is difficult if there is no subdivision, so the Phong shading is typically "Broken." You can Unbreak this edge. (It must be a Polygon Object by then.)
Main Menu> Mesh> Normals> Unbreak Phong Shading

Let's try a different route, for simplicity:
Create whatever you need and place it into a Remesh, then perhaps in Subdivision Surface.
CV4_2025_drs_24_TXps_11.c4d

Is that a way to go for you?

All the best