Icebreaker Avalanche by Andres de Mingo

Andres de Mingo   the author of this nice shot,  kindly explains us how he did the destruction effects using Pulldownit plugin in 3d Max.

It has been a stimulating experience working in this project, using Pulldownit in 3ds Max was easy and fun,  PDI get along very well with Particle Flow to add more debris.

Shattering the ice floor

iceCrack_top

The ice is shattered in several stages, first I drew  a large spline crossing the ice in the middle and use Path-based shatter creating around 400 small shards,  then I applied a Uniform shatter on the whole ground to make all fragments rounded, 80 shards was enough for this. Finally I needed the area around the boat to have more fragments as they will break off in dynamics for this I put a thin box over the ground covering the area I wanted to reshatter and use it as a Shatterit Volume Shape with around 250 additional shards.

iceCrack_front

For the area behind the boat I simply deleted the shards in the middle manually,  for the rest I created a fracture body with Hardness 20 and Clusterize 0, I wanted the ice to break only in the boat area so I set it as Only break and Local Propagation also I set the hull of the boat as a kinematic body to can collide with the ice. When playing the scene the boat was colliding with the ice but several fragments interpenetrated the hull because they weren’t pushed away with enough strength. To fix the problem I created a Pdi Cracker object following the path just in front of the boat and running at its same pace, then I tweaked the Cracker impulse direction until getting the fragments pushed up and colliding with the hull afterwards nicely.

Making the cliffs avalanche

cliffsClusters

I wanted the cliffs behind the boat to start crumbling at some moment, for this I shattered three nearby peaks in around 125 shards each one using Local shatter, then I created a single fracture far all of them and set it as Static-Only Break and reduce it hardness to 10 units to make it overall very brittle. In order to trigger the destruction I created a cluster from the farthest peak adding some break energy and setting it  to start breaking at frame 90, after the boat has started to shatter the ice in front, I made the same with the second peak but this time making it starting to break  one second later and so on, in this way I got the feeling of the shockwave propagating across the cliff. That worked pretty well but some big fragments of the basis start to break off as well in a weird way, to fix the issue I set all fragments of the basis as static to prevent them moving at all.

Adding  more debris

pFlowDebri

I used Particle Flow in 3ds Max to add more debris to the cliffs destruction, that wasn’t difficult. I set a Position Object operator to use the PDI fragments as source for particles then I set a Spawn operator to emit more particles per frame. Finally I set a Shape Instance with a PDI fragment as source to instantiate the particles as geometry. Only trouble was some particles accelerated too much , I remove those weird particles by adding a Speed Test branching to a delete pFlow operators.

Adding  a falling snow effect

FumeFxViewport

The Cliff destruction already looked good but  I needed to add falling snow, I reused the same pFlow particles I have created before to emit smoke with FumeFx.  I didn’t want a dense avalanche of snow because this would hide the falling rocks behind, I just needed a soft covering of snow around the detached fragments.

Preventing the smoke to raise was the main trouble, I set a low temperature value, negative buoyancy (-5) and high dissipation values, finally I got a better look by setting Velocity Difusion to 50 units. The result I got isn’t perfect at all but I hope it gets the feeling of  snow around.

Finally I composed the snow pass in Fusion, adding some blur and adjusting the levels with the alpha gain.

final

Conclusions

It has been a stimulating experience working in this project, using Pulldownit in 3ds Max was easy and fun,  PDI get along very well with Particle Flow to add more debris, generating snow  was the most difficult part, Fume is great for smoke generation but honestly getting a falling snow behavior isn’t easy, next time I would like to try a more specific tool to simulate sand -like effects in addition to Fume.

 

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