Interpolate the normal of a point along a triangle

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Wayne

I took a shot at coding the elegant way.
This is untested virgin code.
Here it is Josh, just for you.. 8)

Point=x,y,z

Triangle=
Ax,Ay,Az
Bx,By,Bz
Cx,Cy,Cz
Anx,Any,Anz
Bnx,Bny,Bnz
Cnx,Cny,Cnz

;---------------------------------------------------------
; Calculate Normal for point=x,y,z

; Calculate the total area, and that of each sub triangle
AreaT#=TriArea(Ax#,Ay#,Az#,Bx#,By#,Bz#,Cx#,Cy#,Cz#)
AreaB#=TriArea(Ax#,Ay#,Az#,x#,y#,z#,Cx#,Cy#,Cz#)
AreaC#=TriArea(Ax#,Ay#,Az#,x#,y#,z#,Bx#,By#,Bz#)
AreaA#=AreaT-AreaB-AreaC

; Calculate coefficients
c1#=AreaA#/AreaT#
c2#=AreaB#/AreaT#
c3#=AreaC#/AreaT#

; Calculate the new weighted normal
nx#=Anx#*c1+Bnx#*c2+Cnx#*c3
ny#=Any#*c1+Bny#*c2+Cny#*c3
nz#=Anz#*c1+Bnz#*c2+Cnz#*c3

;----------------------------------------------------
; Calculate area of triangle using Heron's Formula
Function TriArea(Ax#,Ay#,Az#,Bx#,By#,Bz#,Cx#,Cy#,Cz#)

; Calculate the side lengths
a#=sqr((Ax-Bx)^2+(Ay-By)^2+(Az-Bz)^2))
b#=sqr((Ax-Cx)^2+(Ay-Cy)^2+(Az-Cz)^2))
c#=sqr((Bx-Cx)^2+(By-Cy)^2+(Bz-Cz)^2))

; Calculate half the perimeter
s#=(1/2)*(a+b+c)

; Calculate total Area
Area#=sqr(s*(s-1)*(s-b)*s-c)

Return Area#
End function