FLUID PARTICLE SIMULATION via MAYA BIFROST Amanda VanderZee, Jean-François Coquand, Madeleine Chu
Particle Simulation Bifrost ABOUT BIFROST Water & Contours The tools you use will depend on the effect you want. Particle Emitter for Rain Pros: Simple to use. Offers different types of Precipitation. Great for effects and seeing how it affects buildings. Cons: Pooling water is for short periods of time. Not great for flooding. Bifrost for Waves/Flooding Pros: Epic effects that render awesome and easily. Ability to scale accurately to your city. Simple to use, and has lots of options to add. Great to use for flooding. Cons: Not ideal for small amounts of precipitation (ie: Rain). RAIN SIMULATION LET THERE BE RAIN!
Particle Simulation Bifrost Rain Simulation 1 Once Maya is open, the first action is to create a surface plane. This can be done by clicking on the tab Create and scrolling to NURBS Primitive then Plane. 2 Create any size NURBS plane. Once this is done, you can also remove the base grid by unchecking the option Grid under the Show heading in your current viewport. 3 To set this NURBS plane to be your rain source in the simulation, you will need to ensure Dynamics is selected in the top left-hand side drop down menu. From here, select the Particles tab on your main tool bar and scroll down to Emit from Object. 4 On the bottom right hand of the screen press the Play function to animate the particles. By doing so, you will notice the particles being emitted from random edges and parts of the surface you created.
Particle Simulation Bifrost Rain Simulation Note: To change how fast the rain animation plays, can be done by manipulating the value of the playback range. In this case I changed this value from 120 to 5000, to enable the animation to play longer. THOR s THOUGHTS 5 To change the direction the particles (rain) will flow, first select the particles on the screen. This will automatically bring up the Attributes Editor panel to the right hand side. Under the emitter1 tab, go down to Basic Emitter Attributes. In this drop down, you will want to change the option from Omni to Surface. 6 If you press play and animate the simulation, the particles now flow only uni-directionally. 7 You will notice the particles are moving upward. To reverse this direction, once again go to the emitter1 tab under your Attributes Editor panel. Under the option Basic Emission Speed Attributes change the Speed value to -1.00.
Particle Simulation Bifrost Rain Simulation There are a few options you can experiment with to change the rain fall simulation, which are all done under the Attributes Editor when you select the particles. THOR s THOUGHTS SHAPE OF RAIN PARTICLES 8 Under the particleshape1 tab, go to Render Attributes. In the Particle Render Type drop down, you can select the option streak to provide a more realistic rain particle shape. DENSITY OF FLOW 9 To change the density of the rain falling down, under Add Attributes For click on the Current Render Type button. The two options Tail Fade and Tail Size can be adjusted to create the type of rain fall you are looking to achieve.
Particle Simulation Bifrost Rain Simulation SPEED OF RAINFALL 10 Under the emitter1 tab, scroll down to Basic Emission Speed Attributes. Sliding the values of the Normal Speed section will change it from raining to pouring. You can create a topography and cityscape as your base layer for the rain to collide with. The Outliner panel will help to ensure you select the correct layers. Pulling this Outliner panel up, can be done by selecting WINDOWS > OUTLINER. THOR s THOUGHTS 11 In this new window select your particles first and then press shift to select the topography layer second. Under the Particles tab on your main menu bar, scroll down to Make Collide. Once this is done, your rain particles will interact with the topography created.
Particle Simulation Bifrost Rain Simulation To manipulate how the rain and topography collide with each other, click the tab Particles and select Particle Collision Event Editor. THOR s THOUGHTS 12 In this panel, you will want to enter your Set Event Name. Under event type ensure the Split option is check-marked. Finally, click on Create Event. In creating a particle collision event, you can control the type of interaction that occurs when the particles (rain) collides with the base topography.
Particle Simulation Bifrost Wave Simulation WAVE SIMULATION TSUNAMI WAVE!!! 1 Each Bifrost action has 2 basic elements. One is selecting an object that will function as a liquid emitter. In this tutorial I have created a simple polygon lake. The second element you need is a collider which will be the coastal town I have created. 2 I wanted the rectangular body of water to ramp up against the shore through adjusting its vertices to create a triangular formation.
Particle Simulation Bifrost Wave Simulation 3 Select your body of water and click Bifrost > Create Liquid Select your Collider (the town) and click Bifrost > Add Collider 4 Make sure your UI settings have your animation menu open. There you can click play and check out how your Bifrost will look. More often than not your water will be running in the wrong direction. 5 In order to get it rolling in the right direction you need to open the attributes tab under channels and change the Gravity Direction setting of your Bifrost Liquid Container. Bifrost liquid container is the box that emerged around the object you set as a liquid. 6 What is incredibly awesome about Bifrost is that the particle simulation will understand the contours of your collider and give you an accurate simulation of where water would go in the case of a flood, or a tidal wave.
Particle Simulation Bifrost Wave Simulation 7 My Bifrost was looking like a wild tsunami deluge so I reduced the gravity magnitude from 9.8 to 1.0. OPTIONS/CONTROLS Your basic controls will be found in the Attributes Editor. If you want a greater resolution of your water you can lower the voxel count of the liquid body to have a better, more defined spray. If you do not want a continuous spray but want to simulate a condition like a wave, you start that work flow by selecting your liquid shape and removing the Continuous Emission check box.
Particle Simulation Bifrost Wave Simulation Important Note: Bifrost is based on real world densities and velocities of water. It has a scale of 1 grid unit per meter. If your Bifrost is looking incorrect then either scale it to your model size (1:100 model = 9800 Gravity Magnitude). THOR s THOUGHTS There are dozens and dozens of different variables for you to experiment with from rendering the actual water and refractions to affecting shape and density of the water. The Bifrost is your oyster, so start exploring!