Stop rain/snow from falling through pieces of environment?

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Chris
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Re: Stop rain/snow from falling through pieces of environmen

Post by Chris » 01 Dec 2016, 01:39

CMAugust wrote:A top-down projection doesn't sound like it can account for particles blowing sideways, for one thing.
The projection can be tilted if the particles are falling at an angle. It wouldn't work too good when it's at flatter angles (particles would get blocked by things on the ground near the edges of the loaded cells, and very rarely appear around the player), but it should be fine as long as it's mostly downward-facing.

In the case of Skyrim SE, it's also possible they're using DX11 ComputeShaders (OpenCL for us) to have GPU-accelerated particles with collision detection.

CMAugust
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Re: Stop rain/snow from falling through pieces of environmen

Post by CMAugust » 01 Dec 2016, 02:16

Thats interesting; thanks for the added clarity. Is a GPU-accelerated particle solution via OpenCL also worth a look-in? I don't know if it's considered overkill for OpenMW, but next to Scrawl's ambitions for water post-1.0 it doesn't sound too far-fetched.

Chris
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Re: Stop rain/snow from falling through pieces of environmen

Post by Chris » 01 Dec 2016, 03:40

CMAugust wrote:Thats interesting; thanks for the added clarity. Is a GPU-accelerated particle solution via OpenCL also worth a look-in? I don't know if it's considered overkill for OpenMW, but next to Scrawl's ambitions for water post-1.0 it doesn't sound too far-fetched.
At some point, perhaps. The main issue is that Morrowind uses fairly large "clumps" of raindrops, dust, and snowflakes per particle, so you'd end up seeing a bunch of them blink out of existence when the particle it's connected to is killed. You'd also get those clumps getting through smaller areas because the particle ended up making it through, bringing the whole texture with it. I don't know how Skyrim SE handles that though, whether it just uses more but smaller particles or if it exhibits these drawbacks, as I've never taken a close look at it.

The depth map approach allows for finer detail when particles have relatively large texture faces, and it also works with alpha-tested textured surfaces -- e.g. a flat quad that has a texture with a hole in it, can allow precipitation through the hole since that part of the texture isn't rendered in the depth map, while physical collisions would see a flat surface where you can see a hole.

CMAugust
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Re: Stop rain/snow from falling through pieces of environmen

Post by CMAugust » 01 Dec 2016, 04:25

Perhaps Skyrim SE isn't so different after all. It is possible to see the occasional raindrop falling through holes and gaps in the ceiling (the same is true of Fallout 4), as you describe. Unless the individual particles are just really really small.

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Pherim
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Re: Stop rain/snow from falling through pieces of environmen

Post by Pherim » 05 Dec 2016, 22:35

CMAugust wrote:Perhaps Skyrim SE isn't so different after all. It is possible to see the occasional raindrop falling through holes and gaps in the ceiling (the same is true of Fallout 4), as you describe. Unless the individual particles are just really really small.
As far as I know (can't check right now) it does use much smaller rain particles so yes, the detection is more accurate than in Morrowind with MCP. So all we need is replace the rain in Morrowind with more and smaller particles. The original Morrowind has an ini setting for the maximum number of raindrops, so it would seem all that needs to be done is make a thinner rain mesh and increase the number in the ini... :roll: great, now I have to check that. :D

edit: yes, it's possible, no problem. Resizing the rain mesh diameter to half the original value already significantly reduces clipping. Of course, I only made this very quickly in NifSkope, which also made the individual raindrops thinner. But with a properly edited mesh this should work nicely. The same goes for snow, I guess.

jayhova4x4
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Re: Stop rain/snow from falling through pieces of environment?

Post by jayhova4x4 » 30 Jul 2017, 08:50

The most jarring example of where weather does not collide with objects is inside the canton tunnels in Vivec. Seeing rain inside the tunnels destroys immersion. My $0.02

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