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In this tutorial, author Cristian Pop will show us how to use ParticleFlow to cover our scenes with snow, procedurally. Using a simple ParticleFlow setup, we'll be able to create impressive snow scenes, in a short time. Let’s take a look!
Every few weeks, we revisit some of our reader's favorite posts from throughout the history of the site. This tutorial was first published in June of 2011.
Create some simple objects or use your own models. Later, we'll cover them with snow. For tutorial purpose, I created two hi-poly objects, a "Torus Knot" and a "ChamferCylinder".
Select the objects and group them by going to Group>Group.
These objects will be used as collision objects for the particles. To speed up the particle simulation process, add a "MultiRes" modifier to the group and decrease the "Vert Percent" value to 30%.
Go to the Command Panel>Create>Space Warps>Deflectors and create a planar "Deflector" under the group. It will be used to kill the particles that fall outside the objects.
To be able to use the group as a collision object within "ParticleFlow", create a "UDeflector" space warp object.
Under "Object-Based Deflector", click the "Pick Object" button and select the group. Leave the "UDeflector" properties unchanged.
In the Top Viewport, create a "ParticleFlow" particle system. Make sure that the "ParticleFlow" icon covers the objects. Set the "Viewport Quantity Multiplier" to 100.0%.
Move the "ParticleFlow" icon above the group.
Open the "Particle View" window by clicking on the "Particle View" button (Modify panel) or by pressing "6" on your keyboard. Then, delete the following operators, "Rotation" and "Shape".
In the "Birth" operator, set the "Emit Stop" to 0, to generate all the particles on the very first frame. Set the "Particle Amount" to 5000 (or increase it if needed).
In the "Speed" operator, set the "Speed" to 100.
Add a "Collision" operator to our current "Event" by dragging it out from the "Depot" at the bottom of the "Particle View window". Add the "UDeflector" space warp object to the "Deflectors List". Under "Test True If Particles > Collides", set the "Speed" to "Stop". If you move the time slider, you will see that the particles that are colliding with the objects, will stop and stay on the surface.
To kill the particles that are falling outside the group, create a second "Collision" operator. Add the planar "Deflector" to the "Deflectors List".
Create a "Delete" operator to a new "Event". By connecting the second "Collision" operator to the newly created "Event", the particles that are colliding with the planar "Deflector" will be sent to "Event 004", where they will be killed by the "Delete" operator.
Move the time slider to frame 30, and wait for "ParticleFlow" to update the particles.
To create the "Snow Mesh", you can use the "BlobMesh" compound object or "PWrapper" from 3DAliens.
I always add a "Relax" modifier to the "BlobMesh" objects, to smooth the surface.
If everything looks alright, convert the "BlobMesh" object to an "Editable Poly". (Right Click>Convert To>Convert to Editable Poly).
Now, you can delete the "ParticleFlow" icon, the deflectors and the "MultiRes" modifier from the group. And your snow scene is ready to be rendered.
Thanks for reading. I hope you enjoyed this tutorial!