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3ds max 2019 | tyFlow

tyFlow is a new advanced event driven particle / dynamics system plugin for 3ds max that can somewhat be described as the “next generation of Particle Flow*“.
An ‘event driven particle system‘ is a particle system in which the behavior of the particles is defined in ‘events‘. each event contains a collection of ‘operators‘ that control the different aspects of the particle behavior, like their shape, their speed, direction etc. special ‘test operators‘ are used to check if the particles should switch to a different event and so change their behavior.
Setting up an event driven particle system in 3ds max is done through a node based visual interface, in which the nodes in the flow graph are the particle events, each event is a collection of operators and their parameters.

This tutorial demonstrates some fundamental concepts of event driven particles and tyFlow:

1. Using Property Test operators to switch between different motions and shapes.
2. Using the PhysX Shape and PhysX Switch operators to switch between physical and non-physical particle behavior.
3. Spawning new particles and deleting them.

> Note that while understanding the logic of this example is relatively easy, tweaking all the parameters to get it right takes a lot of tests and fine tuning.
Download the example file and playing with the system parameters to get to know how the different operators affect the particles.

Download the tutorial example 3ds max file here

Explanation of the flow graph:

> To create a tyFlow particle system:
In Command Panel > Create > Standard Primitives,
Click tyFlow, and then click and drag in the viewport to create a tyFlow object.
When the tyFlow object is selected, in the Modify panel press the Open Editor button to open the tyFlow editor. Drag operators from the library below to the work space in order to create a new event containing them, or drag them into existing events.

> Note that almost all of the system’s events contain a Display operator set to Geometry mode so that the particle’s actual animated shapes will be displayed in the viewport, and also a Mesh operator needed for particles to be exported to a render engine for final rendering.

1. Particles are initially created in event: ‘Birth’ using a Birth Objects Operator, and are immediately sent to the next event: ‘Physical Falling’ by the Send Out operator.
   > The Birth Objects operator is used to initialize particles directly from scene objects.
   
   Initial setup of the spheres as sources of particles for the Birth Objects operator:
2. The event titled ‘Physical Falling’ is the only event in the system in which the particles behave as PhysX objects who’s motion is governed by physical simulation i.e they fall and collide with the slide model (named Box001).
   The PhysX Shape operator turns the particles into physical simulation objects, and the PhysX Collision operator adds the slide model as a collision object to the simulation.
   A Property Test operator checks if the falling balls fell below -35 in the Z axis, and if so sends them to the event titled ‘Rocket Upward’.
   > Note that in the PhysX Collision operator, the Hull Type of the slide model is set to Mesh rather than Convex to allow the sphere particles to slide inside the slide (a convex hull type would behaves as if it’s filled making the balls fall to the sides)
   > Note that in the tyFlow PhysX settings, the default ground collider has been disabled to allow the balls to fall freely below the 0.0 Z axis position.
   > The (standard) Shape Operator and Speed operators are in this event in order to reset the shape and speed of particles in case they entered this event after already having different shapes ans speeds.
3. The event titled ‘Rocket Upwards’ uses a PhysX Switch operator to deactivate the particles participation in physical simulation, assigns them a new (rocket shape),
   A Force operator referring to a tyWind object causes the particles to accelerate upwards, and a Spawn operator to have each original particle spawn new particles as the rocket trail.
   A Property Test operator checks if the particles have reach a height of 200 and if so sends them to the event titled ‘Chopper back to start’.
   > Note that the Slow, and Rotation operators are in this event to force the particles back to default orientation so the rockets will be aimed upwards.
   > The Spawn operator creates new particles and at the original particle location and sends them to the event titled ‘Rocket flare’.
   
4. The event titled ‘Chopper back to start’ assigns the particles a new ‘little chopper’ animated shape, and uses a Force operator to make them affected by the tyWind object pointing back to the start.
   > Note that the Shape operator has the Animated Geometry option checked, and set to sync by particle age. the animation speed is played back 3 times faster than the original animation.
   > A Property Test operator checks if the particles Y position higher than -150 and if so sends the particles to the event titled ‘find drop location’.
5. The event titled ‘find drop location’ uses a Find Target test operator to make the particles move to the Point Helper object located above the slide and when they have reached it send them back to the event titled ‘Physical falling’ where they start their journey all over again.
   > Note that the Slow operator slows the particles velocity that was inherited for the previous event so they wont overshoot and ‘fly’ further beyond the point helper.
6. The event titled ‘Rocket flare’ defines the shape, speed and direction of the spawned rocket trail particles and uses a Time Test operator to check if the trail particles have existed more than 3 frames and if so send them to the event titles ‘Delete Flare’
   
7. The event titles ‘Delete Flare’ uses a Delete operator to delete the trail particles.

System setup with the tyWind objects responsible for moving the particles in the non-physical events of the system, and a Point helper object that serves as a ‘find target’ for the particles to get back to the initial location above the slide:

Particle shapes for the ‘Rocket Upward’, ‘Chopper back to start’ and ‘find drop location’ events.
Note that the shape pivots are consistently at the center of the ball for the shape switching to work well, and that the ‘chopper’ animation is done at the mesh level using Poly Select and XForm:

* Particle Flow is a powerful event driven particle system that was originally developed by ThinkBox software, ans later bacame 3ds max’s built in particle system.