🔒 Locked

Quaternion Interpolation

Started by yanuart Dec 27, 2001 at 1:43 AM 3 replies 600+ views

Original Post

Dec 27, 2001 at 1:43 AM

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

v71

Dec 27, 2001 at 5:34 AM

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

v71

Dec 27, 2001 at 5:36 AM

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.

yanuart

Dec 27, 2001 at 4:08 PM

well what are those parameters means anyway ??
what about the quartenion for the rotation ??

v71

Dec 28, 2001 at 11:20 AM

  
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

Topic Locked

This topic has been locked by a moderator. New replies are not allowed.