Plane

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On 20/05/2010 at 09:30, xxxxxxxx wrote:

User Information:
Cinema 4D Version:   11.5 
Platform:   Windows  ;   
Language(s) :     C++  ;

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so in math, the equation for a plane is  x + y + z = 0

how do I represent this in the C4D api?

is the result from CalcFaceNormal the same as this equation?

~Shawn

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On 21/05/2010 at 01:01, xxxxxxxx wrote:

Hello you can represent a plane by a point in Space (vector) and a nother normalized vector (the normal of the plane).
all the best
Franz

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On 21/05/2010 at 04:47, xxxxxxxx wrote:

A plane is defined in Cinema as a plane through the planes global matrix.

The orientation parameter of the plane (+/-x, y, or z respectively) defines how the plane is oriented in this matrix.

While a plane mathematically could be defined by a point and a normal only as Franz suggested, this leaves the orientation of the other two matrix vectors undefined.

So, to construct a plane, you need to construct an orthogonal matrix with the offset vector off [= any point on the plane], the normal vector and two new vectors for v1-v3. V1-v3 should be perpendicular to each other = orthogonal.

Depending which of v1-v3 carries your normal vector, set the orientation parameter of plane accordingly.

Hope it helps

Kabe

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On 21/05/2010 at 05:06, xxxxxxxx wrote:

Originally posted by xxxxxxxx

While a plane mathematically could be defined by a point and a normal only as Franz suggested, this leaves the orientation of the other two matrix vectors undefined.

right.... i loose this part, sorry 🙂

to buil the matrix you can start by definig 3 point plane and use this tree point to obtain v1 and v3 with cross vector

all the best
Frabz

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On 26/05/2010 at 02:13, xxxxxxxx wrote:

Originally posted by xxxxxxxx

Hello you can represent a plane by a point in Space (vector) and a nother normalized vector (the normal of the plane).
all the best
Franz

Yes, this is the defintion of an infinite plane.

cheers,
Matthias