Transparency Pixel colour for Sprites on HP Prime

[john gustaf stebbins]

(05-21-2021 09:41 PM)matalog Wrote:  There's nothing silly about that! That's a really good pendulum wave demonstration!

I'll have a good read through it and make sure I understand it. Thanks for sharing that.

You're quite kind.

One of the things that took me a while to work out was that if I drew to a transparent graphic, it would become a solid background, where the drawing affected it. I have another version of of this where the balls are drawn using partially transparent colors for each frame, so you can see the balls behind the front ones. I could not figure a way to create partially transparent sprites with the built in drawing commands. The only command that preserved the alpha value for the graphic itself is DIMGROB.

I've not worked with other graphic systems using transparency. I had expected that if I had a color with transparency (alpha 255) and I drew a color with half transparency (alpha 127) I would get a final color with half transparency (alpha 127). I expect there could be some issues with how this would work in G0 (can't let us see the innards of the calculator :^), but it could be very useful for building images in the other graphic variables.