Bullet Dynamics
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About Bullet Dynamics
LightWave 11 added Erwin Coumans' open source, production-proven Bullet Physics Library to its dynamics tools. This feature is extremely simple to add to a scene, but its use is a little different from the HardFX plugin existing LightWave users are familiar with.
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In order to ensure dynamics calculations are free of problems, it is worth noting these guidelines:
Make your models not too small, or too large, as Bullet gives more predictable results when working with objects sized roughly between 0.4 - 10 m.
Any collision objects such as ground planes should not be infinitely thin but have some thickness.
Objects made of triangles and quads will generally behave better.
When using the built-in shapes within Bullet, have some Collision Margin set. 5mm is a good default.
Bullet doesn't work with negative frame numbers.
Prepare your objects for dynamics, ensuring: >
Models are 'air-tight', meaning all points are merged and there are no un-modeled holes in your mesh (missing polygons).
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All single points and 2-point poly chains are removed. >
Objects don't have extremely long, thin polygons.
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Overview of Controls
In the Layout FX Tools tab that hosts Bullet as well as other motion effects items Bullet's properties are split into the following groups:
Bullet Group
Enable Dynamics - This turns Bullet on and off globally for the scene.
Item Properties - This opens Bullet Properties on the Item tab. If any dynamic objects in Layout are selected when this is clicked, they will be selected in the Bullet panel.
World Properties - This opens the Bullet Properties on the World tab.
Remove Body - Removes selected objects from Bullet, so they are no longer part of any calculations. The Bullet settings for the objects will be lost.
Dynamic Body
Rigid Body - The object will be subject to all the Hard Body settings that Bullet can offer, such as Gravity or Density, but will not break apart.
Parts Body - This is a great accompaniment for the Fracture tool. It keeps your object whole until there is a collision event.
Deforming Body - This adds a Soft Body matrix to your object. Your mesh will now be deformed following the rules you set for it.
Collision Body
Static Body - This is the type to add for objects that will not move or be subject to other forces, but will react with other bodies. A floor is a good example of a static body.
Kinematic Body - Gives the selected object characteristics similar to Static, but it can be moved through keyframed animation, thus it is an object that is under user control. As with Static, it affects other dynamic items but cannot be affected by them.
By default, LightWave draws an overlay on dynamic objects in OpenGL to show that not only are they dynamic, but what type.
Constraints
Constraints are detailed in full, here.
Forces
Forcefield, Vortex, Explosion - These three Bullet Dynamics types share similarities in their settings and effect. They are global to a scene and affect all other dynamic objects in the scene although falloffs can be created using gradients to isolate the effects to certain regions of 3D space. Note, textures for Force settings using World Coordinates won't work correctly.
Examples:
Baking Simulations - Creating static animations from simulations
Further Examples - Other Bullet tutorials
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Contributed to by Jubei (Julian Herring)