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walkingcarcass

Rotation matrix

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I like the quaternion way of rotate-by-angle-about-axis, but the quat->matrix is ugly. Is there a simpler way to build a matrix which rotates by theta about V? BTW, when looking down the vector, the rotation is counter-clockwise, right? ******** A Problem Worthy of Attack Proves It''s Worth by Fighting Back

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You can just use your quaternions to rotate your vertices directly without using a 4x4 matrix at all.

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could you please tel me how kdogg, i cant figure out on my own...

walkingcarcass: check out the last tutorial on this site about quaternions. it should answer all your questions.

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To rotate a vector v, represent v as [0, v]. Where q is the rotation quaternion:

Rot(v) = q * v * q-1


multiplication of quaternions:

[s1,v1]*[s2,v2] = [s1*s2 - v1[dot]v2, s1*v2 + s2*v1 + v1[cross]v2]

inverse of a quaternion:

q-1 = (1/||q||)2*[s,-v]

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I already know quaternions. I want their equivalent matrix, not converting or substituting.

********


A Problem Worthy of Attack
Proves It''s Worth by Fighting Back

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