Questions RE flowing liquids

[karlexceed]

I decided to try creating a mod that adds liquid mercury. It was mostly straightforward, but there are a few things that I have questions about.

You can check out the WIP mod here: https://github.com/karlexceed/liquid_mercury/tree/main

First, am I correct that setting drowning above 1 will have no effect? I tried setting it to 10, but the player doesn't seem to drown any faster.

Second, I removed paramtype = "light" and tried setting post_effect_color to {a=0, r=255, g=255, b=255}, but I am still able to see when submerged:

screenshot_20231209_235647.png (220.83 KiB) Viewed 2225 times

And lastly, I am getting this weird dark shade at the edge of flowing sections, after removing paramtype = "light":

screenshot_20231209_235640.png (956.73 KiB) Viewed 2225 times

Are these drawing issues basically just a case of the engine not being set up to handle opaque liquids?

[Blockhead]

The engine really doesn't seem to be able to handle nodes that aren't drawtype normal and at the same time don't have paramtype light. You'll notice the flowing liquids case a shadow as if they are a full node even when they are partial, along with the bad lighting on some of them. - in the middle of those three at the bottom there would have 0 light from anything else on the horizontal axes around it, so it's drawn oddly dark. I tried messing around with glow = 14, and light source = 1 and so on, but it doesn't really help.

Here's a visualisation of the difference between cobble and the flowing corner node of mercy - two screenshots, same camera position; GIMP difference mode between layers and then cranking the exposure up. Very similar shadow.

[Desour]

A node can only store light info if it has paramtype="light". You'll always want to set this for all drawtypes but normal, as Blockhead already said.

The a in {a=0, r=255, g=255, b=255} is alpha. 0 means that the color is fully transparent.

[karlexceed]

That's funny - I had assumed that the alpha value was inverse of that. Sure enough, setting that to 255 solved for the view from underneath the liquid.

And adding paramtype = "light" back looks correct now as well with the correct alpha set. Now if only there was reflectivity/albedo...

[Blockhead]

That's funny - I had assumed that the alpha value was inverse of that. Sure enough, setting that to 255 solved for the view from underneath the liquid.

And adding paramtype = "light" back looks correct now as well with the correct alpha set. Now if only there was reflectivity/albedo...

Good to hear things look good now, but I had thought that you were also asking that the liquids be opaque to light at the engine level, such that if you were trapped in a hole under a layer of mercury between layers of glass, it would block light out. I don't think that's possible. But if that's not what you're after then at least I guess this thread has run its course.

[Nininik]

I have a rhing where some of my liquids are invisible for some weird reason

[Blockhead]

I have a rhing where some of my liquids are invisible for some weird reason

Please ask in a different thread and post a screenshot and version info.

[karlexceed]

I had thought that you were also asking that the liquids be opaque to light at the engine level, such that if you were trapped in a hole under a layer of mercury between layers of glass, it would block light out. I don't think that's possible.

That does seem to be the case, at least to some extent. Being submerged in the liquid will block out most of the light (I currently have the alpha set to 250), and as an experiment, I made a glass platform with mercury above and it seems to block at least some of the light from above, though it's nowhere near as dark as it should be if the mercury were totally opaque.

screenshot_20231211_022542.png (635.21 KiB) Viewed 2098 times

And it also works the other direction - I placed some torches underneath the mercury layer and could see them from above.

[karlexceed]

Additional info: It seems that the light transmission works exactly like water, which is unsurprising. More layers means a greater reduction in brightness.

14 layers of mercury is basically pitch black, which is the same as water, and tracks with the information from this page: https://wiki.minetest.net/Light

[Blockhead]

Additional info: It seems that the light transmission works exactly like water, which is unsurprising. More layers means a greater reduction in brightness.

14 layers of mercury is basically pitch black, which is the same as water, and tracks with the information from this page: https://wiki.minetest.net/Light

Right, the wiki is accurate on the behaviour of liquids. I think it would be nice to be able to have opaque liquids or maybe even liquids with a defined light attenuation per node, say 2-3. I probably wouldn't relate it to the texture alpha directly. But that's just a feature request.