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### #ActualJoeJ

Posted 17 December 2012 - 04:26 PM

Hi there,
But i remember the pitfalls with octrees, so that might be helpful, if you don't know it:

The problem is: What to do with an object that is split by one or more grid planes?
Put it in each node and draw it multiple times?
Put it in one node and missing to draw it whaen the node is clipped? (guessing thats your problem)

Solution: Put each object to the node, where this condition is true:
objects bounding box center is inside node
AND the largest dimenson from the objects bounding box <= the dimenson of the node.
AND the largest dimenson from the objects bounding box > half the dimenson of the node.

... this results in large objects at the top levels, and small objects at the bottom levels of the tree.

While clipping extrude the nodes by one half of its dimension at each side (so it has 4 times its volume).
This is the volume that surely covers all objects.

I guess that is called 'loose octree', but i'm not sure.

### #2JoeJ

Posted 17 December 2012 - 04:25 PM

Hi there,
But i remember the pitfalls with octrees, so that might be helpful, if you don't know it:

The problem is: What to do with an object that is split by one or more grid planes?
Put it in each node and draw it multiple times?
Put it in one node and missing to draw it whaen the node is clipped? (guessing thats your problem)

Solution: Put each object to the node, where this condition is true:
objects bounding box center is inside node
AND the largest dimenson from the objects bounding box <= the dimenson of the node.
AND the largest dimenson from the objects bounding box > half the dimenson of the node.

... this results in large objects at the top levels, and small objects at the bottom levels of the tree.

While clipping extrude the nodes by one half of its dimension at each side (so it has 4 times its volume).
This is the volume that surely covers all objects.

I guess that is called 'loose octree', but i'm not sure.

### #1JoeJ

Posted 17 December 2012 - 03:54 PM

Hi there,
But i remember the pitfalls with octrees, so that might be helpful, if you don't know it:

The problem is: What to do with an object that is split by one or more grid planes?
Put it in each node and draw it multiple times?
Put it in one node and missing to draw it whaen the node is clipped? (guessing thats your problem)

Solution: Put each object to the node, where this condition is true:
obj.center is inside node
AND the largest dimenson from the objects bounding box <= the dimenson of the node.
AND the largest dimenson from the objects bounding box > half the dimenson of the node.

... this results in large objects at the top levels, and small objects at the bottom levels of the tree.

While clipping extrude the nodes by one half of its dimension at each side (so it has 4 times its volume).
This is the volume that surely covers all objects.

I guess that is called 'loose octree', but i'm not sure.

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