Hmm… the lighting only works well when using a curve to light the fluid. When one uses blackbody, there is no lighting of nearby surfaces. Is this a bug?

That's very interesting for me to watch. I myself did only pretty static tests and could not observe the lag of Lumen.

I see the reflections are not laggy. But the GI is pretty much. It even seems to miss most particels, and catches just some of them randomly?
Or is this because it catches only particles which come close to the surface?

taby said:
the lighting only works well when using a curve to light the fluid. When one uses blackbody, there is no lighting of nearby surfaces.

What's a curve light? Eventually a emissive spline? And it needs to be created from the trajectory of individual particles? That would rule out emissive smoke, i guess.
Idk what's a blackbody neither.

JoeJ said:
(I have forgotten how this shader is called.)

It's called Intersection Shader. (example https://github.com/microsoft/DirectX-Graphics-Samples/blob/master/Samples/Desktop/D3D12Raytracing/src/D3D12RaytracingProceduralGeometry/readme.md)

Would not require isosurface, nor BVH. You could raymarch the density volume directly. Should be much faster than Iso → BVH.
But idk if there is an option to make such thing interact with Lumen.

JoeJ said:

That's very interesting for me to watch. I myself did only pretty static tests and could not observe the lag of Lumen.

Yeah it is laggy, isn't it….

I see the reflections are not laggy. But the GI is pretty much. It even seems to miss most particels, and catches just some of them randomly?
Or is this because it catches only particles which come close to the surface?

I have no clue what's going on LOL.

What's a curve light? Eventually a emissive spline? And it needs to be created from the trajectory of individual particles? That would rule out emissive smoke, i guess.
Idk what's a blackbody neither.

Sorry, I didn't explain that well. Black body radiation gives a peak in the electromagnetic spectrum based on temperature. So as temperature drops, the peak goes from red-hot to orange-hot to yellow-hot, to gray-hot (smoke). Basically, the gradient is like a rainbow. In UE5 you can bypass black body radiation and define a non-rainbow gradient instead.

taby said:
Sorry, I didn't explain that well. Black body radiation gives a peak in the electromagnetic spectrum based on temperature. So as temperature drops, the peak goes from red-hot to orange-hot to yellow-hot, to gray-hot (smoke). Basically, the gradient is like a rainbow. In UE5 you can bypass black body radiation and define a non-rainbow gradient instead.

Sounds like some convention to describe colors? Color temperature, lux or nits, or such stuff? Or even worse - spectral rendering :O ?
s-RGB? Rec. 709?? Hopeless attempts on uniform calibration??? Linear color space vs. gamma what?? CMYK???? YcBcR?
Vanta black? Black Hole Black? Hawking radiation Purple Haze? Gravitational Greys?? … all that… confusing shit?

nah, nah - not with me. Give me just RGB. And if its higher than one, it's ‘very bright’. That's enough for me.

I am chomping at the bit to learn Vulkan LOL. Must…. Focus… on… UE5!

P.S. Now I just need to win the lottery, so that I can buy a desktop with RTX GPUs. LOL

Dude, in case you're not pulling my leg… Planck and Einstein started quantum physics. It was Einstein's interpretation of the photoelectric effect that proved Planck right: photons are quanta, with an energy of E = h * frequency.

taby said:
P.S. Now I just need to win the lottery, so that I can buy a desktop with RTX GPUs. LOL

I've heard RTX 5xxx will have 6 x faster RT, 12 x more tensor cores, AI DOF, motion blur and player input prediction to compensate lag, on a chip that's only 10 x 10 cm in size.
No more need for computer case, because the GPU is so big that you can now put motherboard and some HDDs inside the GPU.
And you get 3 PSUs for free with it. (only two are needed, the third just in case one melts)

But it won't be cheap. Winning the lottery won't be enough, i'm afraid. So no, it's not for you. I am sorry. But no.

taby said:
I am chomping at the bit to learn Vulkan LOL. Must…. Focus… on… UE5!

Sounds you're exhausted from all those options, tools, effects, content browsers, and sheer awesomeness.
But just as disappointed from those small features you need but aren't there.

Idk what to suggest. Be creative on working around restrictions? Doing it somewhat differently than intended?

I liked this one, very impressive:

This uses MPM method. Simulation is all on CPU. GPU does the rendering.

Framerate was quite bad for me, maybe 20-30 fps. Not really a game, just a tech demo. but cool.

Though, i do not really believe in 3D fluid simulation for games yet. Anything volumetric is crazy expensive. And you know, the lottery….
For a Shmup you sure can keep the fluid box small, but how do you intend to deal with the scrolling?
For my own fluid sim i can set the boundary conditions to a warping mode, so fluid that goes out on the left, comes back from the right. This may be a standard option in UE too.
With some external velocity to drive the fluid at constant speed to the left, this would work similar like a scrolling background, or match the background scrolling visually.
Though, you'd notice the repetition and tiling. Explosion that goes out on the left, comes back from the right? Not sure how to deal with that.

There are some nice 2D games with fluid. Like this:

A fraction of the cost, and much larger simulation area is possible. And Shmup is 2D anyway, so i would consider 2D simulation as well.

taby said:
Dude, in case you're not pulling my leg… Planck and Einstein started quantum physics. It was Einstein's interpretation of the photoelectric effect that proved Planck right: photons are quanta, with an energy of E = h * frequency.

Sigh, i don't even know what ‘pulling a leg means’ : )

But did you hear about the wormhole in a quantum computer? Based on the idea that black hole wormholes and quantum entanglement is the same thing?
Maybe that's some progress on those fields.

But well, enough YT for now ; )

Sorry man. I meant to say are you joking? ?