AC3D Forums - View Single Post - How to select surfaces with normals of a specific direction?

tomtheAtom · 15th May 2006, 05:11 AM

Hi everybody,

I am working with AC3D now for some time mainly to get 3D models for visualization purposes in my Flexsim-Simulation-Models.
So I am still a beginner in AC3D or let me say in using of 3D-Drawing-Programs. In most cases I get a 3D model from someone and import it in AC3D, may change a very few things (material, delete some parts, etc.) and than export the 3D model into a *.wrl file. This *.wrl file I import later into Flexsim to have a nice 3D model.

Anyway, very often I face the problem that the normals of the surfaces does not have the same direction. On some surfaces of e.g. a sphere the normals are facing inside and on other surfaces they facing outside. If I select all surfaces and do flip normals, than the normals are the other way round and I still have my problem.
My problem is, that the surfaces not looking the same, e.g. some of them are visible others are invisible, because of the normals and one-sided-surfaces, I think.
I tried to make all surfaces two-sided-surfaces (found a hint in the forum). This looks good in AC3D but if I export it into a *.wrl and import it in Flexsim, it looks like the surfaces are one sided again or look different.
So on one object I select every single surface, check the direction of the normals and where needed I flip them. Quite a lot of work.

I am just wonder if this is the only possibility to do this or is there an easier faster way?

So in other words, is there a way to make the surfaces of e.g. a sphere only to look outside?
Is there a way to select all surfaces where the normals "look" in one specific direction?

I would be thankful for every help or hint. If there are further questions about my problem, please do not hesitate to ask.

Thanks in advance.

tom the (A)tom

P.S.: AC3D is a great software. Thanks guys for this nice piece of software!

15th May 2006, 05:11 AM	#1
tomtheAtom Junior Member Junior member Join Date: Jul 2005 Location: Germany Posts: 2	How to select surfaces with normals of a specific direction? Hi everybody, I am working with AC3D now for some time mainly to get 3D models for visualization purposes in my Flexsim-Simulation-Models. So I am still a beginner in AC3D or let me say in using of 3D-Drawing-Programs. In most cases I get a 3D model from someone and import it in AC3D, may change a very few things (material, delete some parts, etc.) and than export the 3D model into a .wrl file. This .wrl file I import later into Flexsim to have a nice 3D model. Anyway, very often I face the problem that the normals of the surfaces does not have the same direction. On some surfaces of e.g. a sphere the normals are facing inside and on other surfaces they facing outside. If I select all surfaces and do flip normals, than the normals are the other way round and I still have my problem. My problem is, that the surfaces not looking the same, e.g. some of them are visible others are invisible, because of the normals and one-sided-surfaces, I think. I tried to make all surfaces two-sided-surfaces (found a hint in the forum). This looks good in AC3D but if I export it into a *.wrl and import it in Flexsim, it looks like the surfaces are one sided again or look different. So on one object I select every single surface, check the direction of the normals and where needed I flip them. Quite a lot of work. I am just wonder if this is the only possibility to do this or is there an easier faster way? So in other words, is there a way to make the surfaces of e.g. a sphere only to look outside? Is there a way to select all surfaces where the normals "look" in one specific direction? I would be thankful for every help or hint. If there are further questions about my problem, please do not hesitate to ask. Thanks in advance. tom the (A)tom P.S.: AC3D is a great software. Thanks guys for this nice piece of software!