Hey all,
This is my first attempt at making something with physics simulations involved. I hope to over-fill this glass bowl with delicious blue flavored gelatin cubes, and maybe top it with whipped cream and a spoon. When finished, this will be part of a fun T-shirt to wear at an upcoming web developer event.
I’m having a lot of fun with this so far, but am struggling a touch. Note how some of the gelatin is spiky and poking out of the glass. I’m wondering how to bake/kill the simulation part, adjust shapes, then dump on some more cubes with a separate simulation. Is there a term I should search for to get started on that?
I used the Cycles engine at 2,000 samples. The gelatin material is a mix shader of glass and glossy blue (glossy a bit brighter blue). The glass is about 7 units tall, with 0.5 unit sized cubes.
I figured out the glass piercing oddness. If one point makes it past into the glass, it gets caught there while the rest of the cube jiggles away, causing a “spike”. Setting the glass collision settings -> “soft body and cloth” -> “outer” or “inner” increased, seemed to fix it (can’t recall at the moment which one I changed). I also tweaked some cloth settings to make the cubes more sturdy.
One odd thing I noticed is that there is a light reflection from the inside AND outside of the glass. Anyone else run into this?
Fantastic! I look at this and actually taste jello
Regarding the light reflection from both the inside and the outside of the glass, that is physically correct and happens in the real world. Every time a light ray encounters a new surface (as defined by hitting a new material with a change in index of refraction), there will be a new set of reflected/transmitted rays.
Oh good! Thanks for the clarification on that. I appreciate it.
On a separate note, the more cube cloth meshes I add to this thing, the more often the physics baking fails, causing cubes to explode outward instead of falling (which is frustrating after a 2 hour wait to calculate it). Should I use a particle system to spit out cubes instead?
Here’s what my current pre-physics bake looks like (which failed, will retry shortly - nothing is touching):
Yeah, an interesting idea for a rendering, definitely! But physics simulations are kinda limited in accuracy. I’ve been trying to simulate simple things like a stick with a hole in it swinging from a peg, a bowling ball knocking over (some subset of) ten pins, a golf club hitting an elastic but stiff golf ball, etc. Results have been poor. I’d like to look more into using other physics engines in Blender, or writing my own. (YIAAPh = Yes, I Am A Physicist.)
Blender’s physics is good for getting a swarm of objects moving overall, setting up basic ballistics, and such, but for realism I’ve always had to bake the physics into meshes and animation curves, and edit by hand, adding shape keys, nudging location/rotation keys, and so on.
There is software with better capabilities, but it costs $$$ so much that only big CG studios in Hollywood and Burbank use it. Even then, even with our fancy GPU computations and extremely advance math tricks, rheology (the mechanics of squishy things) is a tough subject for visually (or scientifically) believable simulations. Creators of characters such as that gelatin monster in the Monsters Vs Aliens movie have, I’m sure, blogs and interviews where they describe how tough it was, 16 hour days and so on, getting that character to look right.
For your work, you will have to put the final polish on by hand. Scrub, scrub scrub, tweaking vertices, pushing those glass-violating corners back in. The good news is that among the gelatin cubes well inside the glass, no one will notice geometric overlaps. But if you have an animation, well, you may be needing enough coffee that the rest of us Blender Artists may be thinking about buying stock in coffee bean farms.
Thanks for the feedback darenw. I truly appreciate your insight on the physics topic.
I started making edits by hand, which has been a initially stressful, but now joyful experience. Luckily I’m only creating a single frame so no coffee bean farm investments will be required today. I am investing in a local coffee shop today as I type.
On the note of baking and editing meshes after physics baking in Cycles (just realized that physics is new in Cycles - totally cool thanks Blender dev people!!): I followed instructions found here, for individual cube, can’t apply to all meshes at once as far as I know.
One thing that threw me off was that scale and rotation were reset. I had to copy values from the original mesh to get things looking normal, then move to its original post-physics position. It works though and I’m learning much!
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I’ll go ahead and mark this one as “finished”, although it’s nothing compared to masterful pieces in the finished forum (much to look forward to!). It’s great for a quick T-shirt. Thanks for the look and tips!
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