Image Distortion Effect possible with Ceator-Defined Displayable?

[gamedriver]

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Hi to all RenPy powerusers,

I am looking for an ingame (=runtime) effect like this:

https://ibb.co/kxxQV2J

1) Some image which is shown in RenPy normally first.
2) The user clicks with the mouse pointer on any point on this image. As long as LMB is hold (or some condition like this) the image is distorted, depending on the movement of the mouse pointer.
3) The user can distort the image in any direction, like it is printed on an elastic rubber tissue.
4) When LMB is released, the image snaps back to normal condition.

I experimented a little with Creator-Defined Displayables, beginning with the example of the manual. At the moment my finding is that such pixelbased image manipulation are not possible in RenPy, only changing alpha and the like.

Am I right or do you think it may be possible to realize such an effect with a CDD?
Or by any other method avialable?

I found this about shaders:
https://github.com/valery-iwanofu/renpy ... /waves.rpy
Unfortunately my knowledge about shading is mediocre, so I am looking for another way, hopefully easier...

[_ticlock_]

Am I right or do you think it may be possible to realize such an effect with a CDD?
Or by any other method avialable?

I found this about shaders:
https://github.com/valery-iwanofu/renpy ... /waves.rpy
Unfortunately my knowledge about shading is mediocre, so I am looking for another way, hopefully easier...

Not sure if you can do this without using shaders (maybe using some image manipulation, pygame library, or other shaders). Here are a couple of examples that you may find useful:
https://github.com/Gouvernathor/renpy-C ... /tree/main
viewtopic.php?t=60668
Maybe you could do something similar, applying some scaling.

However, the correct way to do this is by using a shader and a CDD. The shader should do the distortion. Possibly, it should receive a touch point and drag vector. You can try to find something like that for the fragment shader. For CDD, the event method should update the touch point and drag vector, and in the render method, you can apply the shader to the image with the updated touch point and drag vector.

[gamedriver]

Thanks, _ticlock_. This confirms my fear that I have to confront myself with the occult mysteries of the shader sciences...