void Quaternion::SpheriqueToQuat(const float latitude, const float longitude, const float angle)
{
double sin_a = sin(angle / 2);
double cos_a = cos(angle / 2);
double sin_lat = sin(latitude);
double cos_lat = cos(latitude);
double sin_long = sin(longitude);
double cos_long = cos(longitude);
this->w = float(cos_a);
this->x = float(sin_a * cos_lat * sin_long);
this->y = float(sin_a * sin_lat);
this->z = float(sin_a * sin_lat * cos_long);
Normalize();
return;
}
The result is really bad : If i put the angle value to 1, latitude to 0 and i increase the longitude with a timer, the resulting movement draw a eight on my sphere instead of turning around the equator.
quaternion "SpheriqueToQuat"
Author
Hello everybody !
I'm drawing a sphere in C++/opengl using quaternion to turn around it.
But i have difficulties to implement a correct function to transform sperical coordinate (latitude,longitude) to a quaternion
First, i do not understand why i need an angle to convert latitude and longitude to a quaternion ( i thought it only was for the up vector )
I used the quaternion faq to make my function
Thanks in advance for any advice.
Sébastien.
[Edited by - cbastien on May 16, 2007 4:28:27 AM]
Author
here a temporary version i made, it is not really accurate but it works !
any advice to help me in a better way to do that ?
[Edited by - cbastien on May 16, 2007 4:41:09 AM]
void Quaternion::SpheriqueToQuat(const float latitude, const float longitude, const float angle){ //this is a temporary version // do NOT work Accurately if( longitude>=-180 && longitude<=0 ){ float longi=-(longitude+90); float lati=-latitude; if( latitude <= 0){ this->x = float(longi/90); this->y = float( lati / 180 ); this->z = float(1 - ( lati / 180 ) ); this->w = float(longi/90 * ( lati / 180 ) * 2 ); } else { this->x = float(longi/90); this->y = float( lati / 180 ); this->z = float(1 + ( lati / 180 ) ); this->w = float(longi/90 * ( lati / 180 ) * 2 ); } }else{ float longi=(longitude-90); float lati=-latitude; if(longitude<90){ this->x = float( 1 + ( longi / 180 )); this->y = float( (longi/180) * (lati / 90) ); this->z = float( longi / 180 ); this->w = float( ( lati / 90 ) * (1+longi/180 ) ); }else{ this->x = float( 1 - ( longi / 180 )); this->y = float( (longi/180) * (lati / 90) ); this->z = float( longi / 180 ); this->w = float( ( lati / 90 ) * (1-longi/180 ) ); } }}any advice to help me in a better way to do that ?
[Edited by - cbastien on May 16, 2007 4:41:09 AM]
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