A little <shader demo> that tracks mouse clicks an...

# compose-desktop

[Kirill Grouchnikov]

A little shader demo that tracks mouse clicks and does dynamic RGB channel displacement.

rgb-displacement.mov

[Grégory Lureau]

Does makeForShader actually build the shader? Should you remember it in a real usecase?
Thanks for sharing it, really nice starter-kit to play with glsl shaders👌

[Kirill Grouchnikov]

Yes, probably RuntimeEffect.makeForShader can be `remember`ed. The shader itself is created in the Modifier.graphicsLayer via the RuntimeShaderBuilder and is wrapped with Compose's RenderEffect. Maybe @Nader Jawad can recommend what should and shouldn't be remembered in that flow.

[spierce7]

These small example demos are super fun and inspirational. Thanks for posting them @Kirill Grouchnikov!

[Nader Jawad]

Generally using remember to cache as many objects as possible is preferred. That said RuntimeShader is intended to create a new shader when the uniform parameters change

[Kirill Grouchnikov]

@Nader Jawad - a follow up. Should it be like this (using derivedStateOf for the builder):

[Kirill Grouchnikov]

or like this with two `remember`s:

[Nader Jawad]

If your SKSL shader is constant then you are better off just having a top level constant defined outside of the composable rather than using a remember call. This would be better as your cached RuntimEffect can be accessed from any composable with additional overhead of the remember call. So you could probably achieve the same thing with just a single remember call passing in the uniform values as keys to only create a new shader from the runtimeEffect when the uniforms change

[Kirill Grouchnikov]

Ah interesting. Might involve a lot of keys though for more complex shaders like the ripple.

[Nader Jawad]

I've been told that snapping off a new shader from a RuntimeEffect is supposed to be cheap so you might get away without using remember at all here and instead just use Modifier.drawWithCache to create a new shader from the RuntimeEffect when those parameters change avoiding remember usage entirely

[wwalkingg]

amazing!