Active Body Properties
The settings below only affect Liquid simulations using the Active Body Solver. Active Body simulations using the Fire/Smoke Simulator are not supported yet. |
When working with Active Bodies, make sure to select the original object when tweaking the Per-Node Properties. Phoenix automatically creates a Clone of the original object when you start a simulation. The Clone is a duplicate of the provided geometry whose position and orientation are stored as key-frames. When the simulation is re-started, the Clone is deleted – any changes made to the Per-Node Properties of the clone are lost. If you want to preserve a simulated copy of an Active Body, you can make a copy of the simulated Clone and then move the copy out of the Active Body Solver's layer in 3ds Max's Layer Explorer (everything in that layer gets deleted when the sim is restarted, so it does not interfere with the next simulation). |
Make Active Body Static | phxfdObjStatic – When enabled will make the Active Body static. It will not be affected by gravity or influenced by the force of the fluid, but will still act as a collider for the other active bodies and the fluids. Collider Type | phxfdObjColliderType - Specifies the shape used by the Bullet Solver to represent an object. - Precise Concave (Slow) - The geometry is decomposed to a set of convex meshes that move together. This shape is useful when simulating concave objects such as a torus, hollow tube or fractured geometry.
- Simple Concave - The geometry is converted to a single representation of a concave mesh. This option is faster than using Precise concave, but is less precise during complex collisions.
- Convex (Fast) - A collision shape from the convex hull of the geometry.
- Capsule (Faster) - A capsule shape over the geometry.
- Box (Faster) - A bounding box over the geometry.
Using a single collision type for the majority of the colliders improves performance. This way the collision calculations will be faster. |
Specify Mass (kg) | phxfdObjSpecifyMass, phxfdObjMass – Specifies the total mass of the Active Body, in kilograms. Use this option when you have a rough estimate of the real-world mass of the Active Body. Note that the specified Mass will be automatically divided by the computed volume of the original object to reach the final density – as a consequence, the specified Mass is evenly distributed across the entire object. Ideally, all elements of the original object should have roughly the same Mass. E.g. when simulating a ship, it would be best to remove high-volume, low-mass geometry such as sails and ropes. Specify Density (kg/m3) | phxfdObjSpecifyMass, phxfdObjDens – Specifies the Density of the Active Body object. Use this option when you have a rough estimate of the real-world density of the Active Body. The density of an object is its total mass divided by its volume. Note that the specified Density is considered evenly distributed across the entire object. Ideally, all elements of the original object should have roughly the same Mass. E.g. when simulating a ship, it would be best to remove high-volume, low-mass geometry such as sails and ropes. Density Presets – Provides a rough preset value for the Density of an object of a certain material. Note that the presets are for reference only - you may need to further tweak the Specify Density parameter: - Cork (270)
- Ship Hull (500)
- Wood (700)
- Boat (800)
- Ice (920)
- Water (1000)
- Plastic(1350)
- Rubber (1520)
- Concrete (2400)
- Glass (2600)
- Steel (8000)
Friction with Active Bodies | phxfdObjToBodyFriction – Controls the amount of friction between the Active Bodies. Low amounts of friction will allow objects to slide while high amounts of friction will slow down both the objects' rotation and movement once they come into contact with another object or the ground plane. Friction with the Fluid | phxfdObjToFluidFriction – Controls the influence of the fluid simulation over the Active Body. When the friction is low, the Active Body will act as a perfectly smooth object (e.g. a ball of wax), allowing water particles to slide across the surface. When the friction is high, the adhesive forces between the Active Body and the fluid will cause water particles to affect the movement of the object to a greater degree. Increase this value when simulating an object in a turbulent body of water whose behavior should be more chaotic. Elasticity | phxfdObjElasticity – Controls the bounciness of the Active Body. Higher values will make the object bounce more when colliding with another Active Body or the ground plane. Apply Gravity and Buoyancy | phxfdApplyGravityAndBuoyancy – When disabled, the body will behave as if in zero-gravity. On earth, an object floats above water because of two forces: Gravity pulling it down, and the Buoyancy of the liquid pushing it up. Depending on the densities of the liquid and the floating object, those forces balance out and the object either sinks (if denser than the liquid its submerged in) or floats. When Gravity and Buoyancy are disabled, any force applied to the Active Body will cause it to accelerate indefinitely in a single direction. Override Center of Mass | phxfdObjOverrideCenterOfMass – Allows you to manually modify the position of the Center of Mass gizmo whose initial location is based on the computed mass of the Active Body. To simplify things, an assumption is made that all parts of the object have an equal weight which in many cases is not true (e.g. a ship's hull is much heavier than its sails). Use this option to manually tweak the position of the Center of Mass gizmo to stabilize the Active Body during the simulation. Original Animation Influence | phxfdObjOriginalInfluence – Phoenix Active Bodies are designed so that you can animate the originals and make them follow a trajectory. Then, as the Active Body simulation runs, the original animation can blend with the effect of the fluid on the Active Body. The Original Animation Influence option controls the balance between the animation of the original and the effect of the fluid. If it is 0.0, then the fluid will have full control over the Active Body and any animation it has will be ignored. If this option is 1.0, then the Active Body will try to perfectly match the position of the original object. Between 0 and 1, you can have both effects at the same time. Note that if you don't have any animation for the Active Body original geometry and it is just static, then setting this option above 0.0 will allow you to weaken the effect of the fluid over the body and the Active Body will try to remain still. Additionally, if you just want to reduce the effect of the fluid on the Active Body, you can lower the Fluid Dens. Mult. option in the Active Body Solver. |