Placeholder Image

字幕表 動画を再生する

  • Hi there and welcome to the Maya Learning Channel.

  • Previously in this series, I showed you how to create realistic waves, shaders, and wakes

  • using a combination of BOSS and Bifrost particles.

  • In these appendices, I'll focus on some fun side effects - like simulating rain on a watery surface.

  • As always, a big thanks to Diego Trazzi, on whose work these tutorials are based.

  • So, while I'm going to start with a fresh scene here,

  • I'm going to be using a very similar technique to the boat wake I created in part 3.

  • That is, I'll first use geometry to generate real raindrop collisions on a wave solver,

  • then cache the results to EXR files.

  • I'll start by creating a polygon plane, and then adjusting its height and width to 60.

  • I'll also add plenty of subdivisions, since I want to capture nice round ripples.

  • Now, the easiest way to simulate rain is with nParticles, so I'll just create a new emitter.

  • Then I'll change the Emitter Type to Volume

  • and scale it to the size of the plane to create my cloud.

  • Next, I'll translate my cloud above the plane, but too high.

  • No need to waste time waiting for the particles to fall very far.

  • And now that should be enough to get some rain.

  • Nice.

  • So since the droplets don't fall very far,

  • I should limit their lifespan to 1 second so they don't fall forever.

  • I can then adjust the amount of rain by changing the Emitter's emission Rate.

  • For a light drizzle, I'll bump the value down to 20.

  • Cool, now I need to prepare the mesh.

  • I'll start by opening the BOSS editor and creating a Wave Solver for the mesh.

  • Now, based on previous tutorials, you might try to add the raindrops as influencers.

  • But you can't!

  • As you can see, nparticles aren't compatible with BOSS.

  • Instead, I'm going to have to generate some geometry around each particle first.

  • So with my nParticle object selected, I'll go to Modify > Convert > nParticle to Polygons.

  • Unfortunately, that seems to have temporarily removed my drops.

  • To bring them back, I'll go to the nParticleShape's Output Mesh section

  • and turn down the Threshold value.

  • This reduces the smoothness requirement for generating meshes,

  • thereby making them easier to generate.

  • Now I get these blobs on each particle

  • but they're kinda big, so I'll just reduce the Blobby Radius Scale.

  • That's better.

  • Of course, they still don't really look like raindrops but that's okay.

  • I'm only interested in the collisions they make with the surface.

  • Which I can now do by adding them as a Wave Influence.

  • Now if I play back the scene, I get ripples where the drops hit the surface.

  • I'll just make them more obvious by bumping up the Amplitude value.

  • Once I'm happy with the effect, I can cache everything out.

  • This creates two cache files in our cache folder.

  • One for the Wave Influence, which records where the raindrops impact the water...

  • ...and one for the Wave Solver, which records actual ripple deformation.

  • These allow me to remove the nparticles from my scene, without losing my ripple effect.

  • Now this looks kind of cool on its own, but it's still only on a flat plane.

  • Even if I added an Arnold shader to it, we wouldn't get something very compelling.

  • However, what if we combined it with our finished ocean from part 2?

  • Remember, this is the scene where we projected the spectral waves onto a shader.

  • I'll start by hiding the result plane and showing the BossOutput mesh again.

  • In the BOSS Editor, I'll add a Wave Solver like before.

  • I can also disable these Spectral Wave Solvers since I know the Arnold shader covers them.

  • Now, instead of redoing my entire process from before,

  • I can actually re-use the rain cache we already created and apply it to this new ocean!

  • This time, rather than a Geometry Influence, I'll create an EXR Influence.

  • As you probably guessed, this substitutes EXR files for geometry.

  • I'll just click this file icon, and navigate to the cache we created previously.

  • Make sure you select the BossGeoProperties cache, NOT the BossWaveSolver cache.

  • Remember, this is the cache that recorded where the raindrops hit the mesh.

  • I just need to adjust the file path.

  • First, I'll replace the specific frame number with this generic frame tag,

  • since I want use all the EXR files.

  • I'll also add a project tag to the beginning,

  • just to indicate that the files are local to my current project.

  • And like before, I'll bump up the Amplitude.

  • As well as turn off Collider, since the EXRs are just for the ripples.

  • Now play back the scene, and you'll see the same rain pattern as our previous scene!

  • But in here I can also apply my Arnold shader with all of its spectral wave displacements.

  • Thereby combining my two effects into one!

  • This'll be even more apparent if I cache the Wave Solver and render the entire sequence.

  • I should note that even though I generated this EXR cache bydoing it for real

  • with the whole nParticle rain simulation, you don't have to go that route.

  • If you prefer to create your rain pattern in a 2D compositor or by some other means,

  • it'll work just as well!

  • Speaking of EXRs,

  • we can also use a compositor to define where we DON'T want ripples to show up.

  • So, suppose our water was inside some kind of shelter with a circular hole in the roof.

  • We would only want ripples in the non-roofed areas, right?

  • I can achieve that using an EXR collider, where red denotes where ripples are allowed.

  • Then I can apply it as a second EXR influence.

  • This time, I only want the Collider.

  • And sure enough, the ripples only appear in my red circle.

  • By default, the boundary of this area is pretty hard,

  • but I can soften it using the Wave Solver's Decay Width.

  • Increasing this value widens the area of decay from the center of the sim to the boundary.

  • And as you can see, it gives us a much more natural falloff.

  • And that's a wrap for rain.

  • But if these type of collision tricks interest you, be sure to check out my next video

  • where I'll use them in shallow water to generate capillary waves.

Hi there and welcome to the Maya Learning Channel.

字幕と単語

動画の操作 ここで「動画」の調整と「字幕」の表示を設定することができます

B2 中上級

海をつくる-付録A:雨粒 (Creating an ocean - Appendix A: Raindrops)

  • 59 0
    WC に公開 2021 年 01 月 14 日
動画の中の単語