# TextureID

Texture IDs can be explicitly converted to integers, but not the other way
around. You can add and subtract integers with a `textureid`, however. (This
only works with the integer on the right hand side.)

```
struct TextureID
{
   bool Exists() const;
   bool IsNull() const;
   bool IsValid() const;
   void SetInvalid();
   void SetNull();
}
```

### `Exists`

Checks if the texture exists within the texture manager at all.

### `IsNull`

Checks if the texture is the null index (`0`.)

### `IsValid`

Checks if the texture index is not the invalid index (`-1`.)

### `SetInvalid`

Sets the texture index to `-1`.

### `SetNull`

Sets the texture index to `0`.

The proper way to zero-initialize a `textureid` is:

```
textureid tex;
tex.SetNull();
```

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