Hi John,
On 20 August 2013 06:09, PCJohn <pec...@fit.vutbr.cz> wrote: > ** > We could use Robert's idea to get start and end points. From them, we can > get the biggest value for epsilon as well that would provide "better" > epsilon. It should be smaller in most cases, but still big enough to always > work correctly. I just had doubts small bounding box [-1,-1,-1, 1,1,1] and > start [2,0,0] and end point [1e7,0,0]. In this case, epsilon will be > computed from end point 1e7 by multiplying 1e-5 with the result 100. Thus, > bounding box will grow to [-101,-101,-101, 101,101,101], making false > collision with start point [2,0,0]. Later computation in > LineSegmentIntersector will remove the collision, but it costs > computational time. > > > > After the consideration, my inclination is towards bounding box choosen > epsilon (as opposite to start and end point based epsilon), as the user may > tend to set high values for end points just to pick through the whole scene > or to create fake ray, although not sure if I not overlooked something. > The bounding box based epsilon will likely fail when the size of the box is very small compared to the length of the line segment. It's better to be conservative with this type of operation. If we get the computation right then we should be able to reduce the size of the epsilon considerably. Robert.
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