e This 3D session was an introduction to a plug-in for Autodesk Maya called Bifrost. It provides a node-based framework for building custom effects, including smoke, fire, explosions, sand, snow, instances and more, all available as results you can preview directly in the viewport and render with Arnold. When I learned this definition and watched the examples provided, I was excited for the lesson ahead since we were finally starting simulation work, which I’ve been looking forward to since the beginning (alongside character sculpting)!
Demo & My Work
First, we stretched and flattened a cube to make a plane, but not a flat one like usual. We were going to be making a trough, so the walls needed to be pretty substantial. The obvious next step was to extrude the top face down which would complete the basic shape.
At that point, we could customise it if we wished. Some people changed the form slightly and duplicated it to make a waterfall effect, others kept it as it is, making it slightly deeper or more shallow. I added a slant to mine by selecting the verts on one side and moving them slightly out, followed by the verts on the bottom which I stretched downwards. Using the same technique, I also made the slanted side wider so that the through had a cool, modern look, like one of those fancy sinks you’d find in an expensive house.
After that, we had to create the emitter. This is the object which the water would run from (before applying a material, just particles). You can choose what shape you want the particles to be depending on what shape you decide to make the emitter. We went with a simple sphere to grasp the basics, but you could have star-shaped particles raining down for example. It makes me think of interesting fantastical environments you could create. For example, could you stretch out a primitive as the emitter and make multicoloured rain? Could you increase the particle size enough and disperse them so that stars could be falling?
To actually achieve the effect, however, we had to change Maya’s format type from ‘modeling’ to ‘FX’. Next, we selected the sphere and went to ‘Bifrost Fluids’ which was now an option at the top. There, we chose the ‘liquid’ option and immediately went to the man-with-a-cog icon at the bottom right to change the playback speed to 24fps x 1. I played it back and this point and I could see that the sphere was shedding the particles slowly, almost like a layer of water.
We were warned that the program was especially finicky and lagged a lot with Bifrost but that hopefully, it wouldn’t be a problem later on (which it wasn’t all that much, thankfully!). Now that the emitter was created and the playback settings were all prepped, we had to do one more thing to achieve the realistic water sim we were aiming for: adding a collider. We were all familiar with the concept that colliders give an object physical value and knew that it was necessary to do so for the trough, otherwise the water would just fall straight through. So, we selected the trough and the bounding box around the sphere and went to ‘Bifrost Fluids’ again, where we chose ‘Collider’ this time. I played again and this time there was a visible difference – the particles made contact with the trough and splashed in a pretty realistic way, dispersing and falling off the edges. All of this was happening slowly but we could see that there was a collision, as we wanted.
I paused the video when contact was made, at the point above. The particles are visible at the moment, but very small and hard to see as a collective. So that we could better view how they behaved as a whole, we selected the bounding box again and opened up the attribute editor. There, in a section for the particle display, we increased the particle size to bout halfway so that we could see them much more clearly. I think that they look beautiful! And even without a material, they had the appearance of water, because of their movement and colour.
At this point, however, when I tried to play, the sim disappeared. We were told not to panic and that it was normal for this to happen. Proof that the simulation was still there would come through playblasting, which was our main way of saving our progress throughout the lesson in case Maya crashed. As instructed, I right-clicked the timeline and selected the checkbox next to ‘Playblast’ to pull up to options. Then, making sure ‘save to file’ was ticked, I browsed for a location to save the render and hit the ‘playblast’ button. Thankfully, in the corner I could indeed see the particles, playing from the beginning. Here is the first video:
But what if we wanted a stream of water? To make this happen, I went all the way back to the start of the playback range and selected the bounding box again. This time, however, I was told to go into the outliner. After seeing everything that I had created in the neat listed format, I clicked on ‘Bifrostemitterprops1’ and clicked ‘continuous emission’ in the attribute box, a pretty simple step but it changed the whole simulation! Apparently. I still couldn’t see anything as the sim wasn’t playing. But like last time, even if it wasn’t cashing on the interface, a quick playblast would do the trick, and once I repeated the same steps as last time, I could finally see what was happening. The way that the emitter was shedding the particles was different from the last time; they were pouring from the sphere in a continuous stream, as we wanted. It looked pretty cool, although there was definitely less of a splash.
As you can see, the particles were pretty clunky and the clip feels like it’s cut short. This is because only 120 frames were played in the timeline and those 5 seconds still took a while to playblast. I did change this though since I wanted my sim to look realistic when we would apply a material. I also knew that the particles were behaving as I wanted them to so I turned the particle size back down. I also changed the frames from 120 to 200. This isn’t a massive difference but I was very conscious of how long we had and how much Maya was struggling, even when playblasting. It took a little longer, but this is the third clip. In hindsight, I do wish I had increased the frame number a bit more since it’s still quite short.
Now it was time for the fun part! We could choose what kind of material we wanted to apply to the particles to make them look like different liquids. First, we went back into the outliner and clicked ‘Bifrost liquid 1’, after which we scrolled down in the attribute editor to the meshing options. After opening this, there was one box we were focused on, told to ignore all of the other settings, we just ticked ‘enable’. What this did is allow turn the particles into a mesh and allow us to apply a material. Here is the mesh selected.
The next step was to right-click and hold and choose the ‘assign new material’ option we all know and love. This part of the lesson always makes me excited because it’s like watching what is created come to life. For the trough, I just assigned a blinn and made it slightly darker and transparent, so you could see what was happening inside. For the mesh, however, I added an ‘aistandardsurface’ shader from the ‘Arnold’ section and then went to the presets. There were so many fun options that I could remember such as glass and milk, all available to apply to something that finally moved like them. I’d also like to note that I changed the frame rate back to ‘one frame per second’ here since ’24fps x 1′ was just acting up too much.
I chose ‘gold’ and added a physical sky to my scene as well. In the render box, I was happy to see that it looked exactly like gold pouring into a trough-like and the effect was super cool. However, it wasn’t moving and the playblast was taking far too long. I ran out of time and couldn’t get my golden render but here is an image I saved in order to showcase the appearance of the simulation.
I am so impressed with what I created! This was a simple process and I could tell we were just learning the basics of Bifrost, but already there are so many possible uses such as waterfalls and rivers (or any part of an environment with water), stones and other objects falling in or floating on top, boats and stormy ocean scenes, animals jumping out like sharks or crocodiles, water as a part of a building such as a moat around a castle or a fountain in a museum, waterslides and interesting pool architecture and of course, a blacksmith pouring lava or gold into a mould to make a weapon or powerful ring. When you begin to explore the presets, the options triple, since you could create fantastical or even surrealistic scenes. For example, for my project, I could add moving elements to my 3D models. I hadn’t thought about that until now, but if fluid simulations are these easy to generate, then I could easily throw one into my floating island concept for example, with water falling off the edges. As I predicted, I enjoyed the introduction to sims so much and it’s already one of my favourite parts of the program that we’ve done so far.