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Randomly "Jittering" the direction of a vector ...

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Lets say I have a vector that is pointing in a particular direction. How can I change the direction of that vector slightly along each axis while still maintaining its general direction?

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depends. one dumb solution that comes to mind



float frand(float range)
{
return ((float)(rand()) / (float)RAND_MAX) * range;
}

float frand(float min, float max)
{
return min + frand(max - min);
}

Vector Jitter(const Vector& dir, const float amount=0.01)
{
Vector jitter = dir + Vector(frand(-amount, amount), frand(-amount, amount), frand(-amount, amount));
jitter.normalise();
return jitter;
}


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I think the 'spray' would be inside a box shape. To make it circular.


Vector Jitter(const Vector& dir, const float amount=0.01)
{
Vector dev(frand(-1, 1), frand(-1, 1), frand(-1, 1));
dev.Normalise();
dev *= amount;
Vector jitter = dir + dev;
jitter.normalise();
return jitter;
}



That should make the distribution more circular. although I'm not sure about the distribution. I would think it would have a lot more probability around the centre vector, and a lot less chances of deviating too much. Which wouldn't be bad for a gun bullet spread pattern.

There are all sorts of things you can do to get the distribution you want.

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