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#49

From: Tim Wendt
Date: Thu, 31 Aug 1995 20:49

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What is the test to determine if a vector is is front or behind the partition
vector (2D only ala Doom) when building a BSP tree?  

I've read a few FAQs and articles but the only test I've seen in detail is the
test for 3D polygons (which is the dot product between the normal of the plane
a the polygon edge.)  One of the texts did say it was a simple dot product
between the two 2D vectors.  I pulled out the old linear algebra textbook but
I'm still confused.  The dot product was described as ||u|| ||v|| cos (angle
between the vectors).  How do I find the angle between the two vectors?  Is
this the easiest approach?  Thanks much!

Tim
--------------------------------------------------------
|       "Hmm...beer!" - Homer Simpson
---tim.wendt@daytonoh.attgis.com---------A1200/030/33---

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From: Tim Wendt <tim.wendt@daytonoh.ncr.com>
Subject: BSP tree question
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Date: Thu, 31 Aug 1995 20:49:36 GMT