I want to reverse only normal, but keeping vertex number/order untouch. If i add a reverse sop to a geometry, i can reverse the normal but the vertex order also reversed.

I tried to shift the vertex order(with another reverse sop but in shift mode) but the vertex order just couldn't perfectly match to the original order.

Anyone please help me

Sort node.

BabaJ
Sort node.

i tried, but sort node only sort point and primitive, not on vertex

I'm almost sure that normal direction depends on vertex winding order, so you can't change one but not the other. If not I'm all ears.

Konstantin Magnus

@N = -@N;

im new to houdini. could you tell where to enter this expression?

just hold TAB in your node view and type pointwrangle. Enter the code in there.

Hi Ruudygh,
Could you explain what it is you are trying to solve?

I think A-OC is right here. The vertex winding also controls the normal direction of the polygon. You can simply test this with an add sop closing a polygon. it will be dependent on the order. Thats why it matters which direction you draw a closed curve.

So to my knowledge this is simply not possible as it would break how a polygon is constructed in 3d.
I am just a noob dont take my word on this. :3

Maybe you just have non matching vertex orders which you want to match?

ps: did you try clean sop with reverse winding?

Doudini
Hi Ruudygh,
Could you explain what it is you are trying to solve?

I think A-OC is right here. The vertex winding also controls the normal direction of the polygon. You can simply test this with an add sop closing a polygon. it will be dependent on the order. Thats why it matters which direction you draw a closed curve.

So to my knowledge this is simply not possible as it would break how a polygon is constructed in 3d.
I am just a noob dont take my word on this. :3

Maybe you just have non matching vertex orders which you want to match?

ps: did you try clean sop with reverse winding?

Thanks for taking the time to help me. The original problem is from https://www.sidefx.com/forum/topic/48076/ [sidefx.com]
I am trying to solve this problem over a day now. This thread is just a test step to solve that problem, it may or may not solve the problem at all.

The uv looks good, but looks bad in 3d view. Because the vertex order is clockwise in uv view but counter-clockwise in 3d view. I appreciate it if you could help

EDIT: that problem is solved now. Thanks anyway