Unity Sprite Mesh Generation

Unity Engine
1

Howdy,

How does Unity generate the meshes for sprites that are marked SpriteMeshType.Tight?

I’m trying to do this at runtime, but I keep ending up with quads.

Essentially, I’m taking an image, building a mask, applying the masked texture (after alpha is applied from said mask) to a texture, then creating a sprite at runtime.

Is this even possible with the built in features? If not, any hints on where I might look to achieve this?

Thanks,
R

2

It can only be done in the editor; there’s no option to do that at runtime. Also sprite meshes aren’t exposed, so if you want to do that manually you would have to use regular mesh objects.

–Eric

3

Ah, thanks Eric. I was afraid that wast he case.

That’s too bad, I was hoping to use that to build colliders for the alpha’d shape, but I guess I’ll have to find another method.

4

Hi

You should be able to achieve what you want with

Sprite.Create(Texture2D texture, Rect rect, Vector2 pivot, float pixelsPerUnit, int extrude, SpriteMeshType meshType)

5

Leo,

That’s the code I’m currently using (including passing the mesh type).
Still only generates a quad at run time, ignoring the sprite’s alpha.

6

Hi,

Not sure what might be the problem can you share your code?

Here’s the simple test that I did

        Texture2D t = new Texture2D(256,256);
        Vector2 v = Vector2.zero;
        for(int i = 0; i <256;++i, v.x +=1)
        {
            v.y = 0;
            for(int j = 0; j < 256; ++j, v.y +=1)
            {
                Color c = new Color(1,1,1,1);
                if(v.sqrMagnitude > 400)
                {
                    c.a = 0;
                }
                t.SetPixel(i,j,c);
            }
        }

        SpriteRenderer sp = gameObject.AddComponent<SpriteRenderer>();
        sp.sprite = Sprite.Create (t, new Rect(0,0,256,256),Vector2.zero, 100,0,SpriteMeshType.Tight);
7

Leo,

Thanks for the response. It got me thinking to challenge the assumptions I was making in my previous response, and indeed, while I was using a shader that masked out the main texture based on a second texture, the alpha of the main texture was not being modified, so that leads me to assume that SpriteMeshCreator relies on the main texture alpha? Either wait, I got it working. Thanks!