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derek7

p.n=d question

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if d>0 or d<0 what does it mean? it mean plane face origin if d>0? or someone give more good answer. if there are a point p0 and a plane p.n=d I know if p0.n - d >0 then the point at positive of the plane. but just know p.n >0 or <0 I can get what ?

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d in the plane equation tells you how much the plane is offset from the origin, along the direction of the normal. If d is 0, then the plane passes through the origin. If d is some other value, then all of the points on the plane are "moved" by d * p.n.

When we plug a point into the plane equation, the d value we get is similar; it tells us how much the point is offset from the plane, along the normal. Basically, if we take P' = P - dn, where P is any point, d is the d value of that point minus the d value of the plain, and n is the plane normal, we get P', a point on the plane.

The plane normal points a certain direction. Any point on the side of the plane that the normal is pointing to will always have a greater d value than the plane itself, so when you subtract the plane's d, you always get a positive value. Similarly, any point on the other side will always have a smaller d, so you will get a negative value when you subtract the plane's d.

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