I'm using boxes around participants to indicate boundaries, like so:I would also like to use background colors in the alt/else block, to accentuate which are the expected outcome and which are the error cases. However, if I do this without any transparency, I end up losing track of the box around the first two participants:Adding transparency makes the participant's box apparent again, but the else block's colour isn't the #cc00007f I've set it to:It looks like the colour of the alt block covers the whole box, and the else's background colour is added on top if the alt's. Here's what it looks like if I remove the else's background colour:With solid/non-transparent colours, that's not an issue as the else's colour is going to cover the alt's. However, with transparent ones, it leads to less-than-ideal mixes. ^^My question:- Is there a way to achieve my goal of using transparent colours on the alt/else blocks without them mixing together?Thank you!
So solid red 50% transparent on a white background should look pink not red (mixing equal parts red and white gives you pink).
I agree, and it's what I'm trying to achieve here. ^^If I don't put a background colour on the alt block and set the else block to #cc00007f, I get exactly what you're saying - the first block in the image below. The issue is that I don't get pink, I get a mix of the else block's and the alt block's background. For a side-by-side example, if the alt block is set to a green like #00cc007f and the else block is still set to #cc00007f, I don't get the same "transparent red/pink" colour, it blends with the alt's green and turns orange/brown:The colour used for both else blocks is the same, and yet it doesn't display as the same because it's blended with the alt block's colour. Here's the code used to generate the diagram. What I would like is for the else block to stay transparent red, like this mockup I edited in paint.net:
Hence my question, clarified:- Is there a way to achieve my goal of using transparent colours on the alt/else blocks without the else block's colour mixing with the alt's?
Thanks again! =)
We have fixed this issue with "teoz" rendering engine. Fixing it with legacy engine is too complex.
Someday, "teoz" will be the default engine but right now you have to use !pragma teoz true to enable it.
So you can now have this.
Hope this helps!