Wall mounted mesh !!!

[harikumar001]

Hey Guys,

Have a good day. Stuck with something new here. My program currently allows users to place 3d models in a room from a library and adjust its position.

Some of my models, like paintings, should be wall mounted. Previously I was stuck with the problem of correctly selecting the interior face of the selected room wall to place the mesh. With help from mithrandir i was able to select the inside facing wall of the room correctly.

My program can now mount meshes to a wall by calculating the slope of the wall and making the mesh slope equal to that of the wall and positioning the mesh on the wall. But the problem now, in some cases is that, the mesh is perfectly aligned to the wall but is on the other side, meaning the mesh is rotated by 180 degrees. I know it has something to do with how i get the rotation to be applied on the mesh from the slope. How do I correct the mesh rotation as slopes for 0 and 180 are same.

Any help will be much appreciated

Regards

[Mithrandir]

Assuming you are using the wall normal at some point, just scale the normal by -1 for meshes you want to rotate.

[harikumar001]

Thank you Mithrandir for your reply 

I know i have to rotate in the direction opposite to the normal, but I am unsure to which meshes i must apply the rotation. Some meshes are placed correctly, some are rotated. So I need to find the ones that are rotated. How do I do this?

[serial]

Does it only happen to certain meshes or all meshes placed on the same wall?

[harikumar001]

Its not a problem with a particular mesh alone or a particular wall.

Please see the attached image to get a better idea of the problem

[Mithrandir]

Then you need to fix the wall normals. Or since some convention. I think there is something like right hand rule where you add vertices in counter clockwise direction and the normal will be created id direction of a thumb of right hand...

[Lenn]

I think you can probably just do ComputeNormals on the wall mesh, and then do a collision ray towards the point where you want to attach the mesh, this may give you the right normal. From the TV_COLLISIONRESULT that is. Not sure tho, but you can try it.

[harikumar001]

Thank you Lenn and Mithrandir

Been trying different methods to solve the problem. Lemme try what you guys suggested

[Hypnotron]

edit: nevermind.