FAKE META

FAKE META BALLS AND CELL DIVISION / MERGING WITH XSI

At some point you may end up doing, or even wanting to do some 'inside the body' type stuff and often it means you need some organic gloopy type behavior - such as cells dividing. There are lots of approaches to this and it depends on how close to the objects you need to get. Often - fluid sims or a 'meta' (metaball) simulation would be useful, but fluid can be tricky and frustrating to control and metaball stuff is often extremly heavy and demanding on your computer.

Heres a cheap and dirty but effective way to make something blobby happen with out any messy meta. We are gonna use a good ol' boolean operation.

Open XSI and make yourself a sphere. The default settings will do fine for our purposes. Hit Control + D to make a duplicate/clone. Move it aside so they are sitting next to each other. These will be our cells. You can squash them down into a cell shape if you would prefer. Hit G to hide the perspective grid so we can see a little more clearly. Pretty cool so far eh?

Select the sphere on the right and making sure you have the 'modeling tab open' (hit 1) - go to 'poly.mesh, boolean' and select 'union'.
Your cursor will now have a little icon that is asking you to pick your target/operand for the Boolean operation.
Click on your remaining sphere.
So what has happened? Use the transform to move the sphere to intersect the other. Notice they are now joining together as if they are the same mesh. You should see something like in this image below.

Hmmm interesting. But wait, whats that other thing/wireframe?! Dont worry, its the original sphere/model that the Boolean union operation has referenced. We dont need it right now, but we might do later - so select it and hide it (hit H).
Switch to a shaded view so you can see whats happening more clearly. The spheres are merging, but we have a rather sharp seam that makes it look like they are just intersecting. Hit the + key on your keypad a couple times to add some subdivision. Move your sphere around and you will see them merging/splitting like in the image below. Hey not bad, but we still need to work on it a little to get a more blobby type behavior.

With your object still selected, look under modify in the model tab and select 'deform, relax'.
By adding a relax modifier we are easing the falloff and relaxing the solid shape of our model. Now you should have something similar to the image below. Add a couple more subdivions to really smooth the mesh. Move the sphere around - now we are getting some sort of fluid surface tension looking behavior which is quite realistic and well suited to things like conjoining droplets or dividing cells.

Problem now is that the mesh is relaxed all over. Maybe this is what you want, but it would be nice to retain more of the sphere shape and only relax the conjoining area. Hit '8' to open up your scene explorer - open up the sphere with the boolean and relax operator on it. For some reason, relax is called 'smooth' instead of relax. Most confusing.
Double click on this operator to open up the control tab. You will see 3 tabs inside the relax floater - General, Advanced Settings and Custom Filter.
Its worth spending some time experimenting with all controls/options. Increasing the relax value will enhance the merging of your spheres/objects and further smooth everything out.
For now, im just going to edit the falloff curve which can be found under the Custom Filter tab. Add a control point and adjust the curve into something similar to the image below. This will make the relax modifier fall off smoothly and we can keepy some of our objects original shape.

All thats left is to do set a few keyframes and further tweak or even animate the values of the relax modifiers in accordance with your scene/camera position. Stick a shader on there to see if its blending together without too many problems or artifacts. You could also use some vertex selection/volume selection or even a texture map to control the modifiers influence. Remember the sphere you hid earlier? Unhide this and move it around. Now you can control both objects as if they really were seperate, but they can merge together like a metaball too.
The same effect can be achieved in 3DSmax with a boolean union operation - but to control the objects, you will have to open up the modifier and select the operand listing inside the modifier panel before you can move the objects about. 3DSmax doesnt handle the operation and subdivision as cleanly as XSI, so you may have to stack a few modifiers up to get a satisfactory result.

Heres is the scene file - XSI 6.01 or above - SCENE
The XSI scene has a simple SSS shader and a seperate reflection pass to create a wet look.