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jviruss

CatMullRom

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Hello I´m have a Callmuth Rom equation,but it dont work well. My Equation is: float t2 = t * t; float t3 = t2 * t; output.x = 0.5f * ( ( 2.0f * p1.x ) + ( -p0.x + p2.x ) * t + ( 2.0f * p0.x - 5.0f * p1.x + 4 * p2.x - p3.x ) * t2 + ( -p0.x + 3.0f * p1.x - 3.0f * p2.x + p3.x ) * t3 ); output.y = 0.5f * ( ( 2.0f * p1.y ) + ( -p0.y + p2.y ) * t + ( 2.0f * p0.y - 5.0f * p1.y + 4 * p2.y - p3.y ) * t2 + ( -p0.y + 3.0f * p1.y - 3.0f * p2.y + p3.y ) * t3 ); output.z = 0.5f * ( ( 2.0f * p1.z ) + ( -p0.z + p2.z ) * t + ( 2.0f * p0.z - 5.0f * p1.z + 4 * p2.z - p3.z ) * t2 + ( -p0.z + 3.0f * p1.z - 3.0f * p2.z + p3.z ) * t3 ); The curve isnt smooth between two interpolations.My up axis is z,my right axis is x and my front axis is y. Somebody know if the equation change dependent of axis system? if it change,somebody know the solution for my axis system?

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If you take a closer look at those calculations, you'll find that they do the exact same thing for each axis, so they cannot depend on what you define each axis as.

I can't spot any errors, so maybe the problem is in your usage of the function, but just for reference, here's one that provided me with good results:

double interpolateCatmulRom(
double a, double b, double c, double d, double t
)
double t2 = t * t;
double t3 = t2 * t;

t2 = t * t
t3 = t2 * t

// Tangents at b and c
tb = 0.5 * (b - a) + 0.5 * (c - b)
tc = 0.5 * (c - b) + 0.5 * (d - c)

return
b * (2 * t3 - 3 * t2 + 1) +
c * (3 * t2 - 2 * t3) +
tb * (t3 - 2 * t2 + t) +
tc * (t3 - t2);
}

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