Clipping with Complex Path or Rounded Box

[hugoam]

It would be very very useful if NanoVG provided a way to clip what is drawn with other shapes than just a rectangle. Correct me if I am wrong but I don't think making holes in paths allows to do exactly that.

• Having a Rounded Box scissor / clip would actually cover all my use cases, so that's probably the simplest
• In theory nvgGlobalCompositeOperation provides a way to clip with any complex shape, except it SOURCE_IN only applies to the current path, and not in two different path, making it impossible to achieve the needed result

[satoren]

You have two ways with conditional.

• You can use nvglu* functions if you using OpenGL backend.
• If fill area wider than clipping area. (e.g. Draw textured text)
  1. Hollow out clipping area using nvgGlobalCompositeOperation with destination_out
  2. fill with nvgGlobalCompositeOperation with source_atop (fill for hollow outed area)

[satoren]

I am write example with "Hollow out clipping area". https://github.com/satoren/nanovg/blob/clipping_example/example/example_clip_gl3.c#L51

https://github.com/satoren/nanovg/blob/clipping_example/example/screenshot-clip.png

[TyOverby]

@satoren your links don't appear to work anymore; do you happen to have the code still laying around?

[satoren]

@TyOverby Unfortunately, there are no codes left. I believe it could be implemented in a similar way to HTML5 canvas clipping with nvgGlobalCompositeOperation. It's been six years and my memory is a little fuzzy, but perhaps #312 made it possible.