When rendering Rain?

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8 comments, last by nefthy 18 years, 10 months ago
When rendering rain wat do you use? GL_POINTS? GL_TRIANGLES? What should i use when rendering rain drops? Cheers, Nick
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It depends how fancy you want to be I guess... GL_POINTS would work, though it'd be pretty ghetto ;)

For good looking rain, maybe try a particle system? In other words, have a texture that contains the image of a raindrop or maybe a group of raindrops, and then draw these rain textures falling from the sky.

roos
careful when using particle systems. Depending on the art used for each particle, you may need to used axis-constrained billboards. This is to ensure that when looking to the sky (up) or to the ground (down), the drops still look like falling drops. It will be downright hilarious if u overlook that tiny detail :P
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Try GL_LINES.
John BoltonLocomotive Games (THQ)Current Project: Destroy All Humans (Wii). IN STORES NOW!
hmmmh
maybe do lines
where each drop is a strip of lines with decreasing alpha vales on each vertex?
so the drop seems to stretch and fade out over distance/time


i wanna try that now....
You could just prerender ten frames of rain on a transparent backdrop and draw each frame sequentially over the scene with a big quad. Depends on how realistically you want to model your scene.

Richard "Superpig" Fine - saving pigs from untimely fates - Microsoft DirectX MVP 2006/2007/2008/2009
"Shaders are not meant to do everything. Of course you can try to use it for everything, but it's like playing football using cabbage." - MickeyMouse

I use blended GL_LINES, with the alpha value being low in the "start" point and high in the end. It looks pretty ok.
Quote:Original post by mikeman
I use blended GL_LINES, with the alpha value being low in the "start" point and high in the end. It looks pretty ok.


You can also try to use the technique Niniane Wang used in Flight Simulator [pdf]. It gives pretty good results if your camera moves fastly.

Regards,
I read a paper somewhere (don't have the link, sorry) where the author maintained the human brain cannot distinguish individual drops. He simulated rain by darkening the scene and distorting it using a post-process. It looked very convincing.
check Rog, Rain, Lighting at vterrain.org

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