Collected Snow

In this tutorial we are going to take a look at a method of using Particle Flow and Blobmesh to create a mesh that looks like collected piles of snow.

We can start a brand new 3DS Max file for this, and just take a minute to create an object or two in your scene.

I have created a simple teapot with 12 sides, and a cone pedestal for it to sit on. For this demonstration it will work just fine.

Once you have your objects something like mine, select them both and group them by going into the Group menu above and selecting Group from the menu.

A dialogue box will appear asking you to name your group. Give it a name that makes sense to you, and hit OK.

If you have more than a simple object or two in your scene, you might consider reducing the amount of polygons until the snow is created.

To do this we will use something called a Multi Res.

With your group still selected go to your Modify Tab and in the modifier list add the Multires to the grouped objects.

The multires can reduce the amount of geometry to it's basic shape, which for our purposes will work quite well so there is less for the deflector to have to calculate.

After we have created the snow all we will have to do is delete the MultiRes modifier and our teapot will look normal again.

In the settings for the MultiRes click on the Generate button towards the bottom.

It will open up the upper portion of the settings for you, when Vert Percent lights up, reduce it down to 50.0.

Your objects in the group will change shape and look awkward. While it may not even be necessary to use the Multires for these couple of objects, in a bigger scene it can save you hours of time.

Now go to your create tab, and all the way down to the Spacewarps. Click on the dropdown menu to find the Deflectors.

We are going to make two deflectors, one to collect the snow, and one to kill the snow that falls outside of our group of objects.

First let's create a regular deflector in our top view and make it large enough to extend well past the group of objects.

You can give it a name if you want, I have called mine KillDeflector, as its job will be to eliminate extra particles that we don't want in our scene and help speed things up a little more.

Next create our next deflector, this one should be a UDeflector, we are using it because it turns our objects into the deflector, taking on the shape and attributes of our teapot and cone.

In the modify settings of your UDeflector, make sure to click on the large Pick Objects button and then click your Grouped items. The name of your group should show up right above the button.

Now we are ready to create our particles. Press 6 to open up Particle View, or you can find it in the Graph Editors menu at the top of your screen.

You should be familiar with the particle view window by now, just remember that the light grey area is our stage where we will add our operators, the dark grey area to the side is the command panel where we will adjust each of the operators settings, and the white area with the list in it is called the depot, this is where we find what we wish to add to the flow chart.

First drag and drop an Empty Flow from the depot to the stage.

Then a birth to the empty stage below the new PF Source box we just made:

And connect the blue node to the empty circle node between the two event boxes, like above.

Then select your birth and adjust its settings in the command panel to the right.

I want all my particles to spawn at once, so I have set both Emit start and stop to frame 0.

I started with 10,000 in the amount setting, we can always increase or decrease as needed later, but working with blobmesh we will need quite a few particles in order to get a solid shape.

This might take some time to calculate in the end so be ready.

Then add a position icon by dragging it in between the Birth operator, and the Display01 operator and dropping it.

This will make our particles emit from the orange icon that has been created for us in our scene, more than likely under your objects.

Find it and drag it up above the objects with your move tool.

With the icon still selected, go to your modify tab so we can adjust its settings.

Set the icon type to Circle, and then increase the diameter of the circle until you cansee that the icon in your viewports is going to completely cover your objects.

Then make 100% of your particles viewable in the viewport.

Then return to particle view, and add a speed underneath the Position Icon operator.

The defaults in the speed should work ok for us, next find and add a Shape operator and drag it under the Speed.

We can leave it set to its default of cube, since in the end we will be deleting the actual particles and letting blobmesh create our geometry, but I do recomment changing the size (which depends how big your objects are in the first place. I have reduced mine to 1.0.

If you click on the Display01 operator below our shape, and change the top dropdown to Geometry you will be able to see your particles as cubes.

If displaying the geometry cubes slows your computer down you can always change it back to ticks as soon as you make sure the cubes are going to be the size you want.

Next find and add a Collision operator to below the shape.

This will be the one we use to kill the particles that don't land on our objects.

In the settings, click the By List button and add our regular deflector, remember mine was named KillDeflector so I could find it easily.

Since the Collision operator is a test it will come equipped with a new blue node, this means that as soon as any of our particles collide with this particular deflector it will be sent off to a new event. The event that is connected to the blue node.

Find Delete in the depot and drag and drop it in the empty grey area of the stage to the left of our first Event 01 box.

Then connect the new blue node to the empty circle above the new Event 02 box.

We can leave the Delete at its default, so that when these particles collide with our deflector, they will just be erased from the scene.

Next add another collision operator from the depot, and drop it right underneath the first collision we made in Event 01 box.

This one will be for collecting the snow on our grouped objects.

Select it and adjust the settings to the right in the command panel.

Add the UDeflector this time to the Deflectors list.

and make sure that the first Collides Speed is set to Stop.

this will make our particles stop moving the second they hit the teapot or the cone.

Move your timeline scrubber to frame 30 or so and let it calculate. You should see something like this.

That's really it for the particles, now we will go to our Create tab, under Geometry, and then move your dropdown list to Compound Objects.

Find and click on the Blobmesh button, and then click somewhere in your viewports to create it.

With the blobmesh icon selected, go to your Modify Tab in order to adjust the settings.

You can reduce the tension to make the globs connect a little easier.

Reduce the Evaluation Coarseness: levels to 1.0 in viewport to give you a better idea of what it will look like in the end.

Click the Add button and select the PF Source 01 from the list.

Blobmesh should appear in your scene, it may take several minutes to calculate as Blobmesh is not the fastest of things in the world. If you like blobmesh and want to do more stuff with it, I recommend a plug-in called PWrapper from www.3daliens.com .... it works a lot like blobmesh, but gives you a bit more control and works about a million and ten times faster.

When it finishes calculating you should see something similar to this.

Gloppy like snow, but still a little rough around all the edges right?

We'll fix this by adding a modifier called Relax to the blobmesh.

Increase the iterations in the settings after you add the Relax to 5 or 6.

This isn't creating more geometry like a meshsmooth or turbosmooth, instead it is just relaxing the corners and rounding them out a little more.

Your blobmesh will immediately look about a thousand billion gajillion times better now.

Now right click on your blobmesh to bring up the quad menu, and simply convert it to Editable Poly.

Now you can simply delete your particle system, delete that MultiRes modifier from your objects, texture your snow, add a smooth if needed, and bam! Collected snow for your scenes.