Krakatoa Geometry Test¶
Available in Krakatoa v1.1.0 and higher
Introduction¶
- This bonus operator uses the same kd-tree acceleration structure employed by the PRT Loader for culling particles by volume to implement a Geometry test inside Particle Flow.
- Other than the PRT Loader, only ONE geometry object can be specified per operator, but you can use as many operators as you want.
User Interface¶
- This Test can send out particles that are
- Inside the specified volume
- Outside the specified volume
- On Surface - exactly at the surface.
- If an open volume is used, particles will determine the “inside” and “outside” location based on the surface normals - particles seeing the backside of the geometry will be considered “inside”.
For example, if you create a Plane primitive and select as the Geometry object, any particles “seeing” the plane’s faces from the backside will be considered “inside”, thus allowing you to split the world space into two without a closed volume!
- The Distance Threshold functionality available in the PRT Loader is also implemented in this operator:
- Off - no distance threshold will be applied
- Less Than - particles that have passed the Inside/Outside test and are closer to the surface than the specified threshold will be sent out
- Greater Than - particles that have passed the Inside/Outside test and are farther to the surface than the specified threshold will be sent out
- The None button can be used to pick a valid geometry object.
- It is advisable to use closed non-self-intersecting surfaces, although open and concave objects might also work.
Keep in mind that a Teapot primitive is an open volume with severe self-intersections and several “misformed” faces with no area, so it is a a good example of bad geometry when used as Culling Volume.
- The Remove Object button can be used to remove the current object without specifying a new one.
