Krakatoa: Test Disintegration Project

#1

I would like to disintegrate a character for fun. I have got two layers - one is for background and another one is for foreground character with alpha. I used the same steps as in this tutorial by Bobo.

I created a plane facing to camera and applied a simple material to it. For shader, I slotted a projection map (Camera Map Per Pixel) of the foreground character to Ambient Color, Diffuse Color and Opacity Channels. I set the Mono Channel Output in map to Alpha.

In Particle View - I created empty Flow and connect the PF Source 01 (Viewport % set to 0.005) to Event 01 consisting Birth (10 million particles, Emit Start and Emit Stop set to 0), Position Object 01 (Plane 01), Material Dynamic 01 (with material applied) and Display 01 (set to Dots).

I test rendered the Krakatoa particles, the color and alpha (opacity) are working fine. I saved the particles (PRT) with the following channels - Position (float32[3]), Color (float16[3]) and ID (int32).

I loaded the particles (PRT Loader) in the same scene. As in tutorial - I created another empty Flow (PF Source 02) and with operator “Krakatoa PRT Update 01” under it. I created “Krakatoa PRT Birth 01” operator under Event 02 and appended a Collision operator connected to another event (Event03) with Force operator (Wind and Drag).

Particle View:

PF Source 01
Render 01 (Geometry)
---- connected to Event 01 ----
Birth 01 (At 0 T 10000000)
Position Object 01 (Plane 01)
Material Dynamic 01 (01 - Default) --> Projection Material
Display 01 (Dots)

Saved Particles…

PF Source 02 (Viewport % 0.005, Render % 100)
Render 02 (Geometry) Visible % 100
Krakatoa PRT Update 01 (ID and Color checked)
---- connected to Event 02 ----
Krakatoa PRT Birth 01 (PRT Loader 01)
Collision 02 (SDeflector 01) --> Connected to Event 03
Display 02 (Ticks)

Event 03
Force 01 (Wind01 and Drag01)
Display 03 (Ticks)

Here are my questions:–

The particles in alpha region (plane) is solid black when loading particles, they should be transparent. How do I retain opacity? Should I create a custom float channel for Opacity before saving the particles as the opacity channel is not listed?

I’m confused with “Render” and “Viewport” check boxes under PRT Loader - do I need to enable both as the new particle will be generated by Collision operator (SDeflector) and the color (and other channels) will be inherited. Am I correct? It took very long to update the particles on per frame basis if both “Render” and “Viewport” are enabled. Should the PRT particles always be loaded 100% in viewport?

Am I using the correct approach?

#2

Here is a whole tutorial dedicated to plane with Alpha channel dissolving:
http://software.primefocusworld.com/software/support/krakatoa/tutorials.php
Since there is no dedicated Opacity channel in PFlow, you have to work around by passing the data via the MXSFloat channel - see the tutorial for the exact steps.

As for the “Render” and “Viewport” options, they define whether the particles will be active in the Renderer and in the Viewport. For example, imagine having 10 partitions with 100K particles each (1 million in total). You can check all 10 for rendering, but just one for viewport. Thus, you won’t have to show all 1MP in the viewport which would be relatively slow, but still render them all.

You don’t have to show ANY particles in the viewport in order to render or reload in PFlow - only the render state and percentage of the PRT Loader is respected when rendering or loading in a Krakatoa PRT Birth/Update operator. So the viewport percentage could be left at 1%, or could be completely disabled, or one or more sequences could be unchecked for “Viewport” - as long as they are set to render 100% of all partitions, you will still get everything in the final image.

#3

Thanks Bobo! I will check the tutorials.

It managed to render out the current setup (with opacity not working - will check the tutorial), but both new particles and loaded particles were rendered out. It took about 52 min to render out the current setup, is that too long?

I need to render out the birth particles only - Krakatoa PRT Birth 01 - not the PRT loaded particle. I unchecked the “render” in PRT Loader, the render was completely black and the Krakatoa PRT Update Channels (Color and ID) were removed. The channels are available again when I check the “Render” in PRT.

#4

When you pick the PRT Loader in a Krakatoa PRT Birth, you should get a prompt saying something along the lines of “Do you want to disable the Renderable property of the PRT Loader so it does not render in the final rendering?”. At that point answering with Yes would have unchecked the “Renderable” checkbox in the Object Properties (NOT in the PRT Loader’s rollout!) and made it non-renderable. The alternative is to uncheck the “PRT Loaders” option in the Krakatoa Main Controls rollout so only PF Geometry would be respected.

When you unckeck the “Render” option in the PRT Loader though, it stops loading particles from the files, so the PFlow gets no particles either and cannot even figure out what channels were in these particle files (thus the unchecking of the Color and ID options - they don’t exist in an empty stream).

#5

Thanks Bobo! I’m getting there nicely! I used PRT Volume.

What is the best way to visualise the particles with wind warp? I tried to reduce the particles in viewport but the result is not similar in the render. It is quite slow to visualise 1 million particles (10% of total) loaded on i7 Eight Core, 8GB ram machine.

As a Maya user, it is a lot harder to control the wind (turbulence) in Max. I applied the same forces to dummy particles to check/visualise the effects. It looked good in the viewport, but it looked different and insignificant when I linked the same forces back to the original particles.

Once again, thanks Bobo for your time!

#6

Are we talking about Wind Force in a Particle Flow?
Several things to keep in mind:
*Particle Flow is single-threaded at the moment, so 8 cores will not affect it much.
*The Integration Step in the Viewport and Renderer in PFlow default to different values. Thus to get the exact same influence, you will have to set both to the same step (either 1 frame or 1/2 frame which is the default for rendering and slower but more precise).
*The settings of the Wind space warp are a bit counter-intuitive - you have to use very small values for both Frequency and Scale, usually around 0.01 / 0.05 - in order to produce large-scale turbulent effects, otherwise you will get mostly random noise.
*There is a free plugin called “BetterWind” which, nomen est omen, is better. It was developed by Grant Adam and might be a good idea to try… http://rpmanager.com/plugins/BetterWind.htm

#7

Thanks! Yes, I was referring to Wind Force in particle flow, been playing around to get the effects I wanted. I’m getting there with the scale and look of the turbulent effects. Thanks for the link to BetterWind force - I will try it today.

I would like to gently dissolve the character, starting at the shoulder area. Not too uniformly - the effects need to look a bit irregular. The character needs to ebb piece by piece and the behavior of particles need to look a little bit like dissolving ink under water. I guess I will need use a lot of animated Space Deflectors starting at the shoulder area and then spread to the whole body. Is there any way to trigger the irregular effects other than using the Deflectors?

The particles are not self-illuminated as I want the particles to have some self-shadowing. The particles on the first frame look solid but the alpha is solid gray, shouldn’t it be solid white?

Thanks so much for your time!

#8

There are many ways to do that.
One way would be to use the Krakatoa Geometry test which lets you create volumetric “gizmos” using arbitrary meshes. It is only available in the commercial version of Krakatoa, not in the Evaluation version, if that makes any difference…

The particles are not self-illuminated as I want the particles to have some self-shadowing. The particles on the first frame look solid but the alpha is solid gray, shouldn’t it be solid white?

Gray Alpha means the density of the particles does not accumulate to 1.0. Since you can control the Density for the Lighting and Final Passes separately, you could set the Lighting Pass Density to the current value, then increase slightly the Final Pass Density until the Alpha is solid. This will preserve the appearance of the shadows and produce while Alpha. If you only increase the Final Pass Density, your shadows will get darker, too.

#9

This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.