Ebiten: vector: Add various shapes

[hajimehoshi]

• Rectangle
• Circle
• Ellipse
• Arc

This should be easily implemented by using LineTo.

[beoran]

As per our talk on slack, I propose we could port Allegro's triangulator to Go,
(https://github.com/liballeg/allegro5/blob/master/addons/primitives/triangulator.c),
then implement the same functions as the allegro primitives, ported to Go. These are based on triangulations as well. The API is: https://www.allegro.cc/manual/5/primitives.html

[hajimehoshi]

Thank you for the info! Please give some time to consider since I don't have enough bandwidth...

[hajimehoshi]

• Let's add ArcTo
• Rename BezierCurveTo to CubicTo?
• Rename QuadraticCurveTo to QuadTo?
• Add ConicTo? (See https://docs.microsoft.com/en-us/xamarin/xamarin-forms/user-interface/graphics/skiasharp/curves/beziers#the-conic-b%C3%A9zier-curve)

[hajimehoshi]

https://skia.org/user/api/SkPath_Reference#SkPath_arcTo

An arc is represented as a conic Bezier curve. Interesting.

arcTo appends at most one Line and one conic. arcTo implements the functionality of PostScript arct and HTML Canvas arcTo.

[fr3fou]

any news?

[hajimehoshi]

There is a 'vector' package and an example using it.

• github.com/hajimehoshi/ebiten/vector
• github.com/hajimehoshi/ebiten/examples/vector

The API is still unstable.

[hajimehoshi]

Now vector has Path and you can add segments by LineTo, QuadTo and CubicTo. They are similar to Skia's functions. The path can also be filled with a solid color. ConicTo does not exist yet.

https://github.com/google/skia/blob/master/src/core/SkPath.cpp I'm referring Skia implementation to add more user-friendly functions like arcTo. It would take more time than I expected and I'll do this in the next milestone maybe...

[gabstv]

In the meantime, if anyone wants vectors (and they aren't rendered/updated on every frame) they can use https://github.com/fogleman/gg to render into a texture, and then create a new *ebiten.Image from it. If the shapes need to be dynamic, you could use a "is dirty" pattern: http://gameprogrammingpatterns.com/dirty-flag.html

[fr3fou]

Is this still ongoing or was it closed by #1111 or PRs that are related to that

[hajimehoshi]

This is not related to #1111. I don't have enough bandwidth to work on this now.

[hajimehoshi]

I'm busy with porting Ebiten to Switch and fixing audio issues for v2.1.0. Let me change the milestone.

[beoran]

Do you mean the Nintendo Switch? That's great news! 🙂

Op za 16 jan. 2021 13:45 schreef Hajime Hoshi [e-mail]:

I'm busy with porting Ebiten to Switch and fixing audio issues for v2.1.0.
Let me change the milestone.

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[hajimehoshi]

Yes :-)

[beoran]

Wonderful! Please document it well, I would love to port my puzzle game to
the Switch.

Op za 16 jan. 2021 18:17 schreef Hajime Hoshi [e-mail]:

Yes :-)

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[hajimehoshi]

Of course we're preparing documentations, but unfortunately I cannot make the document public due to the NDA.

[hajimehoshi]

Note to myself: how to render vector graphics with GPU:

• https://github.com/servo/pathfinder
• https://github.com/linebender/piet
• https://github.com/Const-me/Vrmac#2d-graphics