AWS Thinkbox Discussion Forums

Box #2 -> Save Particles Hangs/Crashes

Deprecated Krakatoa MX Beta Bug Reports
#1

This is a bit of a tricky one. I have a box 2 simulation that hangs in Max 2011 and crashes 2012.
I’ve isolated the offending condition when using a custom data channel in the solvent operator, generated from the color of the closest surface. The weird part is that if I use another custom data channel (Birth ID % 2 > 0 == true) it does not hang. I know this sounds like a Box 2 problem, but it renders correctly and only hangs when I try to involve Krak to save the particles to file sequence. I’ll cross-post with Oleg.

I’ve supplied a premade file as well as steps:

  1. Create a Box 50x50x50 with an animated gradient so that a white band animates across the faces.
  2. Open Particle View and add a PhysX Flow.
  3. Replace the Birth Grid with a Birth operator. Change emit Stop to 0 and Amount to 200.
  4. Change the Shape operator to Size of 5.0.
  5. Add a Position Object operator below the Birth Operator and choose the cube as the source object. Enable Separation and set the Distance to 5.0, making sure that the cubes do not overlap.
  6. Add a Data Operator below the Shape Operator. Add a Select Object sub op and select the box as the source object. Add two geometry sub ops - One set to Point Color and the other set to Closest Point By Surface. Wire the Select Object into both, and the resulting Point data into the Point color subop. Add a Condition Subop and wire the Point Color to it. This will automatically add a convert subop set to Length. Set value A of the condition operator to .5. Add an Output New operator and wire the condition to it. Now if the color of the closest surface value is > .5, the data channel will be true.
  7. Add a Glue Operator below the PhysX World operator.
  8. Add a Solvent Operator below the Glue Operator. Enable Limit Solvent By Data and set the Data Channel to the opeartor you created in Step 6.
  9. The animation plays as expect.
  10. Set Krakatoa to the Rendere and set the Render setting to Save Particles to File Sequence. The sequence hangs around frame 13.

Some notes:
This does not happen when the data channel is set to to a different operator, for instance setting every other birth ID to true.
This does not occur when using the Birth Grid operator, but does when using Birth Stream, as well.
Box2Solvent_Krak_Crash.max (276 KB)

#2

I cannot currently test this out because we do not have access to Particle Flow Box 2. I have emailed Oleg about this and I will look into your example scene when that gets sorted out.

#3

Sorry dude, I have totally been meaning to check this out.

I can get it to Save to Sequence when I move the Solvent above the PhysX World.

It is a rare occurrence to put any operator other than a Specific Data Op, Display or PhysX Test below a PhysX World. A few Standard Tests work below it too.

I basically think of Box#2 this way: If I want to effect the physics in the simulation I put the ops above the World, if I want to effect the particles after the simulation step I put the ops below the World. This works 85% of the time. Basically all PhysX Operators (not PhysX Tests) need to go above the World.

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