Treads seem squashed / stretched / deformed

posted to: Modeling the Tires

Hi, I'm having a bit of a problem getting the treads to look right. I think the shape I have is relatively close to the instructors:

treads.png

but after I apply the shrink wrap, the treads get squashed / stretched across the wheel. They also appear on the inside of the tire, which seems weird.

tire.png

Here's a link to the project file:

https://drive.google.com/file/d/1bOoc1cXQTKua6y9xVtHuEYUr8qULu6pF/view?usp=sharing

  • Martin Bergwerf replied

    Hi jammingammon ,

    Your Normals are inconsistent:

    Nrm.png

    As they are basically just planes, SHIFT+N won't do you any good here. Manually select the red ones and ALT+N > Flip.

    (In a general case, where there are many red and blue 'planes', you can deselect everything and then enable Backface Culling in the Viewport Shading dropdown Menu, and select only the blue ones (or the red ones, from the back).)

    Some of your Objects do not have their Scale Applied!!!

    In Edit Mode bring your treads closer to the Wheel (by Scaling and Moving) they are supposed to get Shrinkwrapped to, to get less squash and stretch. I recommend using Relative Offset in the Array Modifier instead of Absolute (set it to something like 0.6 in Z) and use Fit Curve in stead of Fixed Count.

    The Solidify can have an Offset of -1, when you don't want the treads on the inside.

    • 👌
  • jammingammon replied

    Hey, Thanks for your response.

    For some reason, the normals are consistent when I look at the file. I'm using 3.1 if that makes any difference. I did notice that my tires themselves have backwards normals, but fixing that didn't change anything. I tried applying scale on the curve, the tires, and the treads, it doesn't make a difference in the squashing / stretching. Also tried moving the treads closer to the tire, changing to relative offset / fit curve, etc. it didn't make a discernible difference. I did get the treads to disappear from the inside of the tire with the offset set to -1.

    Looking at it further, I think the squashing behavior has more to do with the curve modifier than the shrinkwrap. When I disable the curve modifier, the treads are elongated across the x-axis, when I enable it, they get compressed across the x-axis. I'm still stuck on how to fix this.

    Thanks for your help.

  • Martin Bergwerf replied

    Hi jammingammon ,

    You are absolutely right about the Normals; I must have messed up, because they are indeed consistent. (And no, the Blender Version doesn't make a difference for the Normals)

    Try this, Add a new Bezier Circle and Rotate it in Object Mode and Scale it in Edit Mode to the right orientation and size. Use that new Circle as the Curve in the Modifiers.

    Scale and Move the treads in Edit Mode (Use Relative Offset in the Array Modifier to make your life easier).


  • Omar Domenech replied

    I think this old tutorial might help you understand that curve thing a bit. Hopefully.

    https://cgcookie.com/lessons/modeling-a-chain