# Drawing as subractive?

**URL:** <https://forum.juce.com/t/drawing-as-subractive/33223>\
**Category:** General JUCE discussion\
**Created:** [May 3, 2019, 7:56pm UTC](https://forum.juce.com/t/drawing-as-subractive/33223 "2019-05-03T19:56:10Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![DaveH](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.juce.com/daveh/32/4924_2.png) [@DaveH](https://forum.juce.com/u/DaveH)\
**Post date:** [May 3, 2019, 7:56pm UTC](https://forum.juce.com/t/drawing-as-subractive/33223/1 "2019-05-03T19:56:10Z")

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Hi, is there a way of drawing something with ‘subractive’ rendering. I can do it with OpenGL, but I’d like to use Juce to draw ellipses.

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**Author:** ![alassandro](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.juce.com/alassandro/32/4297_2.png) [@alassandro](https://forum.juce.com/u/alassandro)\
**Post date:** [May 3, 2019, 8:02pm UTC](https://forum.juce.com/t/drawing-as-subractive/33223/2 "2019-05-03T20:02:30Z")

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There’s [`Graphics::excludeClipRegion()`](https://docs.juce.com/master/classGraphics.html#a50949e3315daf0cb8c3c0abbdb272720) for simple areas

You could also use [`Graphics::reduceClipRegion(const Path&)`](https://docs.juce.com/master/classGraphics.html#ab3718c74592ec0c1d0cb4e6fc5cec0f6) or [`Graphics::reduceClipRegion(const Image&)`](https://docs.juce.com/master/classGraphics.html#a735b5096ea063020134fdf1c570dec9a) to set up masks

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**Author:** ![DaveH](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.juce.com/daveh/32/4924_2.png) [@DaveH](https://forum.juce.com/u/DaveH)\
**Post date:** [May 3, 2019, 8:17pm UTC](https://forum.juce.com/t/drawing-as-subractive/33223/3 "2019-05-03T20:17:36Z")

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Cool. I’ll look into that, thanks!

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**Author:** ![matkatmusic](https://avatars.discourse-cdn.com/v4/letter/m/dfb087/32.png) [@matkatmusic](https://forum.juce.com/u/matkatmusic)\
**Post date:** [May 4, 2019, 12:41am UTC](https://forum.juce.com/t/drawing-as-subractive/33223/4 "2019-05-04T00:41:48Z")

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if you’re drawing paths, try flipping the winding.

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**Author:** ![DaveH](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.juce.com/daveh/32/4924_2.png) [@DaveH](https://forum.juce.com/u/DaveH)\
**Post date:** [May 7, 2019, 8:41pm UTC](https://forum.juce.com/t/drawing-as-subractive/33223/7 "2019-05-07T20:41:16Z")

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OK, I can’t exclude an opaque area Image, just a rectangle and I can’t draw zero alpha ellipses, so I’m just going to draw the whole off-screen bitmap in a very faint black and white, it seems OK to be honest, and it gives a good hint as to what’s happening. Thanks!!! 🙂