Firstly, I’m a complete noob, but thoroughly enjoy my very steep learning curve with Unity. Also, if this has already been discussed, my apologies but I couldn’t find a related thread upon searching the forums.
I’m busy building a fairly rudimentary scene and importing meshes from blender. I have created a disc type model (by profiling and spinning) and when I use the asset in unity it is only solid from one side, if I rotate around the object in the scene or game view certain faces become transparent from the opposite angle, I’ve tried using .blend and .fbx formats but it persists. This is also happening to text that I have rendered in blender then used in unity.
thanks for replying, but I’m not entirely sure of what you refer to. Can you elaborate on what you mean by “ensure that you have a triangle into both directions when modelling it”
I’m sorry if this is obvious but I’m new to both modelling and unity. I assume you mean I need to make sure this is done in Blender prior to using the asset?
Every triangle in 3d has an implicit direction based on the order of the vertices that make it up. If the order is clockwise the direction is one way and if the order is counter-clockwise the direction is reversed. In many 3d packages you can only “see” a triangle when the camera is on the side that the direction is pointing at. Often there is a setting to automatically see the triangles from both sides, but in real time this is off to make sure things are as quick as possible. There is no automatic way to do this so in order to “see” both sides you need to have 2 triangles one clockwise and one counter-clockwise. You only do this where absolutely necessary as it will make displaying each triangle twice as slow.
thanks for the explanation, it is thorough why does this not happen with say a cylinder in the shape of a disc and does with my mesh?
I’m just not clear on the ‘you need to have 2 triangles’ part. I currently have this disc shape that, after your explanation, I understand is in one implicit direction, how does the mesh have two directions in order to render this properly in unity?
What is best practise the for something that needs to be viewable from both sides?
I see, so as my shape is symmetrical I could just create half, duplicate invert and merge meshes? Assuming that would work, it doesn’t really help with text that I have extruded and imported, as this is also only viewable from one side, how would one handle rotating text for example?
Also, just hypothetically by your explanation, what would apply to the sides of the cylinder? If it is visible from the outside would it be invisible from the inside of the cylinder?
Generally 3d apps have an option to reverse the direction of polygons. I don’t use Blender but I’m sure if you search you will find a tool to do that.
As for the question about the cylinder, correct once you are inside it will dissappear unless you give it a thickness and make the inside wall reversed.
actually, when I look closely that did make a difference, but it just inverted the mesh in unity (well, what is viewable anyhow), which from name flip sounds like it’s doing what it should… what I need is the mesh viewable from all sides so I’m not sure flip is exactly what I’ll need…
It is, you just need 2 copies in the same place if its a disk.
If its the extruded text then you need to only flip the bits that are currently invisible.
In Blender if you turn on display of normals as in the screen grab above they should all be pointing outwards.
If that is the case you are good to go in Unity.
thanks, this has all really helped, I was about to post a question about just flipping the the faces that aren’t visible… but you’ve answered that… thanks
last question, are terms like faces and normals interchangeable, I’m guessing not, but I’m unsure of the correct way to refer to them… What, strictly speaking, is a normal exactly?
Well this is stuff you really need to know about. Do some googling, or look on wikipeddia for more info. Its a big subject and you won;t get far without knowing the basics. Good luck!
why does this not happen with say a cylinder in the shape of a disc and does with my mesh?