Flavor 8 - Polygon Properties (planes)

---------------------------------------------------------------------------------------------------------------------------------------------------------

    LONG    PURPOSE
    ----    -------
    00-03   Flavor Flag  (08 00 00 80)
    04-07   Value #A
    08-11   Value #B
    12-15   Value #C
    16-23   Value #D (read 8 byte words instead of 4)
    24-27   Flavor Offset #1
    28-31   Flavor Offset #2
    32-35   Flavor Offset #3

Ax + By + Cz + D = 0

Flavor Offset #1 #2 #3
        I have found calls to Flavor #1, #4, #7, #8, #11, #12 and #15 offsets.

In Andre's words :

First 3 values set the x,y and z values of a vector set at a 90 degree angle from the plane the polygon is drawn on.
The angle is 90 degrees for any line that can be drawn within that plane. Marcelo named it the directional vector (DV).

The vector is always drawn towards the viewer. So if you want a polygon to be drawn in both the driving direction and when riding the track backwards you have to have 2 polygons with 2 DV's that have a 180 degree angle between eachother.

To extrapolate the values from 2 points:

The Dot Product
(x1, y1, z1)  .  (x2, y2, z2)  =  (x1)(x2) + (y1)(y2) + (z1)(z2)

the dot product is in the equation to find the plane.
I can't remember exact meaning of dot product (cross is normal vector),
but dot is a projection or something (words of Jon).

It's needed for the plane equation

----------
({x, y, z}-point).normal
 
point is the point which is used for the start of the 2
vectors which are made from other 2 points to the point.
Then cross product of those vectors for normal.

(words of Jon again)

I have found this webpage to be a big help on understanding this.
http://reality.sgi.com/cgi-bin/bspfaq/bsp?8.txt