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yanuart

Quaternion Interpolation

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Can somebody give me the basic of what quaternion and the interpolation process so that it can make a smooth path ?? Plzzz... I''m not very good at math so any basic things will do and will be appreciated very much

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sure here it comes
  
void __forceinline QuatLerp( const qVect p, qVect q, float t, qVect qt )
{
int i;
float omega, cosom, sinom, sclp, sclq;

// decide if one of the quaternions is backwards

float a = 0;
float b = 0;
for (i = 0; i < 4; i++) {
a += (p[i]-q[i])*(p[i]-q[i]);
b += (p[i]+q[i])*(p[i]+q[i]);
}
if (a > b) {
for (i = 0; i < 4; i++) {
q[i] = -q[i];
}
}

cosom = p[0]*q[0] + p[1]*q[1] + p[2]*q[2] + p[3]*q[3];

// very small value


if ((1.0 + cosom) > 0.00000001f) {
if ((1.0 - cosom) > 0.00000001f) {
omega = acos( cosom );
sinom = sin( omega );
sclp = sin( (1.0f - t)*omega) / sinom;
sclq = sin( t*omega ) / sinom;
}
else {
sclp = 1.0f - t;
sclq = t;
}
for (i = 0; i < 4; i++) {
qt[i] = sclp * p[i] + sclq * q[i];
}
}
else {
qt[0] = -p[1];
qt[1] = p[0];
qt[2] = -p[3];
qt[3] = p[2];
sclp = sin( (1.0f - t) * 0.5f * __PI);
sclq = sin( t * 0.5f * __PI);
for ( i = 0 ; i < 3 ; i++ ) {
qt[i] = sclp * p[i] + sclq * qt[i];
}
}
}


[edit: added source tags]


Edited by - Magmai Kai Holmlor on December 29, 2001 2:37:17 PM

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Sorry i''ve posted too quickly , perhaps, the qVect actually is
simple a float a[4] array , and __PI is the venerable PI this is easy , if you have something more to ask, just do it.


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void __forceinline AngleQuaternion( fVect angles, qVect quaternion )
{
float angle;
float sr, sp, sy, cr, cp, cy;

angle = angles[2] * 0.5f;
sy = sin(angle);
cy = cos(angle);
angle = angles[1] * 0.5f;
sp = sin(angle);
cp = cos(angle);
angle = angles[0] * 0.5f;
sr = sin(angle);
cr = cos(angle);

quaternion[0] = sr*cp*cy-cr*sp*sy; // X

quaternion[1] = cr*sp*cy+sr*cp*sy; // Y

quaternion[2] = cr*cp*sy-sr*sp*cy; // Z

quaternion[3] = cr*cp*cy+sr*sp*sy; // W

}

void __forceinline QuaternionMatrix( qVect quaternion, fMatrix matrix )
{
matrix[0][0] = 1.0f - 2.0f * quaternion[1] * quaternion[1] - 2.0f * quaternion[2] * quaternion[2];
matrix[1][0] = 2.0f * quaternion[0] * quaternion[1] + 2.0f * quaternion[3] * quaternion[2];
matrix[2][0] = 2.0f * quaternion[0] * quaternion[2] - 2.0f * quaternion[3] * quaternion[1];

matrix[0][1] = 2.0f * quaternion[0] * quaternion[1] - 2.0f * quaternion[3] * quaternion[2];
matrix[1][1] = 1.0f - 2.0f * quaternion[0] * quaternion[0] - 2.0f * quaternion[2] * quaternion[2];
matrix[2][1] = 2.0f * quaternion[1] * quaternion[2] + 2.0f * quaternion[3] * quaternion[0];

matrix[0][2] = 2.0f * quaternion[0] * quaternion[2] + 2.0f * quaternion[3] * quaternion[1];
matrix[1][2] = 2.0f * quaternion[1] * quaternion[2] - 2.0f * quaternion[3] * quaternion[0];
matrix[2][2] = 1.0f - 2.0f * quaternion[0] * quaternion[0] - 2.0f * quaternion[1] * quaternion[1];
}

....please don't make me expalin the theory behind quaternions
it is too long for a post....:-(((((
i hope this function will be usefull for you


[edit: added source tags]

Edited by - Magmai Kai Holmlor on December 29, 2001 2:39:16 PM

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