# render_source var (atom)

Source: https://ref.dm-lang.org/atom/var/render_source

### Default value
> null

### Possible values
> Any non-empty text string

If any icon uses `render_source`, the renderer will look for another icon with a matching `render_target` value on the visible map, and draw that in place of the `icon`/`icon_state`/`dir` that it normally would. The same render target might be used as a source multiple times, and for a complex image this can save some rendering time. This is also usable for special effects such as [filters](https://ref.dm-lang.org/notes/filters/index.md) that might require copies of an image.

> [!note]
> 
> The corresponding `render_target` *must* be visible to the player for a render source to be used.

The replacement icon from the `render_source` will be anchored to the bottom left of the icon it replaces.

Other vars that would normally affect the appearance of this icon, such as `color`, `transform`, `filters`, `appearance_flags`, etc. are all applied. Additionally, if this object has overlays, underlays, or visual contents, those will still be drawn as well.

> [!note]
> 
> Any mouse hits on this object belong to the object itself, not to the object used in the `render_source` or its children. If you want mouse clicks and other behavior to go to the source, use the `PASS_MOUSE` [appearance flag](https://ref.dm-lang.org/atom/var/appearance_flags.md).

### See also
- [render_target var (atom)](https://ref.dm-lang.org/atom/var/render_target.md)
- [appearance_flags var (atom)](https://ref.dm-lang.org/atom/var/appearance_flags.md)