ok I understand that was a correction :)
To summerize it all;
B = N * (N . A) and C = A - B
Where A is the object velocity vector,
N is the normalized vector from nearest point on the wall to the object,
B is the force coming from the wall in response to A,
and C is the resulting slide vector that the object will follow.
Sliding vector from velocity vs a wall
[edit: oops beaten ...]
I'll just clarify something here that might make it easier to understand. The projection of a vector u onto another vector v is given by
projv(u) = (u.v)/(v.v) * v
where . represents dot product. In your case B is the projection of A onto the wall normal, which I'll call N. If N is a unit vector then the above simplifies to
B = projN(A) = A.N * N
since N.N = |N|2 = 1
To get the sliding vector C, as you have said simply compute C = A-B.
I'll just clarify something here that might make it easier to understand. The projection of a vector u onto another vector v is given by
projv(u) = (u.v)/(v.v) * v
where . represents dot product. In your case B is the projection of A onto the wall normal, which I'll call N. If N is a unit vector then the above simplifies to
B = projN(A) = A.N * N
since N.N = |N|2 = 1
To get the sliding vector C, as you have said simply compute C = A-B.
At the moment _I_ think it is correct ;-)
N dot A should be negative, so that B points against the direction of N. In
N * (N dot A)
only a single vector of non unit length is contained, so the length should be projected correctly. Yes, I think now it is ok.
N dot A should be negative, so that B points against the direction of N. In
N * (N dot A)
only a single vector of non unit length is contained, so the length should be projected correctly. Yes, I think now it is ok.
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