codebase / stimlib

  #ifndef RTS_QUATERNION_H

  #define RTS_QUATERNION_H

  

  #include <stim/math/matrix_sq.h>

  #include <stim/cuda/cudatools/callable.h>

  namespace stim{

  

  template<typename T>

  class quaternion

  {

  public:

  	T w;

  	T x;

  	T y;

  	T z;

  

  	CUDA_CALLABLE void normalize(){

  		double length=sqrt(w*w + x*x + y*y + z*z);

  		w=w/length;

  		x=x/length;

  		y=y/length;

  		z=z/length;

  	}

  	CUDA_CALLABLE void CreateRotation(T theta, T ux, T uy, T uz){

  		vec3<T> u(ux, uy, uz);

  		CreateRotation(theta, u);		

  	}

  	CUDA_CALLABLE void CreateRotation(T theta, vec3<T> u){

  		vec3<T> u_hat = u.norm();

  		//assign the given Euler rotation to this quaternion

  		w = (T)cos(theta/2);

  		x = u_hat[0]*(T)sin(theta/2);

  		y = u_hat[1]*(T)sin(theta/2);

  		z = u_hat[2]*(T)sin(theta/2);

  	}

  	CUDA_CALLABLE void CreateRotation(vec3<T> from, vec3<T> to){

  		from = from.norm();

  		to = to.norm();

  		vec3<T> r = from.cross(to);			//compute the rotation vector

  		T l = r.len();

  		if (l > 1) l = 1;					//we have seen degenerate cases where |r| > 1 (probably due to loss of precision in the cross product)

  		T theta = asin(l);				//compute the angle of the rotation about r

  		//deal with a zero vector (both k and kn point in the same direction)

  		if(theta == (T)0){

  			return;

  		}

  		//create a quaternion to capture the rotation

  		CreateRotation(theta, r.norm());

  	}

  	CUDA_CALLABLE quaternion<T> operator *(quaternion<T> &param){

  		float A, B, C, D, E, F, G, H;

  		A = (w + x)*(param.w + param.x);

  		B = (z - y)*(param.y - param.z);

  		C = (w - x)*(param.y + param.z);

  		D = (y + z)*(param.w - param.x);

  		E = (x + z)*(param.x + param.y);

  		F = (x - z)*(param.x - param.y);

  		G = (w + y)*(param.w - param.z);

  		H = (w - y)*(param.w + param.z);

  		quaternion<T> result;

  		result.w = B + (-E - F + G + H) /2;

  		result.x = A - (E + F + G + H)/2;

  		result.y = C + (E - F + G - H)/2;

  		result.z = D + (E - F - G + H)/2;

  		return result;

  	}

  	

  	CUDA_CALLABLE matrix_sq<T, 3> toMatrix3(){

  		matrix_sq<T, 3> result;

  	    T wx, wy, wz, xx, yy, yz, xy, xz, zz, x2, y2, z2;

  	    // calculate coefficients

  	    x2 = x + x; y2 = y + y;

  	    z2 = z + z;

  	    xx = x * x2; xy = x * y2; xz = x * z2;

  	    yy = y * y2; yz = y * z2; zz = z * z2;

  	    wx = w * x2; wy = w * y2; wz = w * z2;

  		result(0, 0) = 1 - (yy + zz);

  		result(0, 1) = xy - wz;

  		result(0, 2) = xz + wy;

  		result(1, 0) = xy + wz;

  		result(1, 1) = 1 - (xx + zz);

  		result(1, 2) = yz - wx;

  		result(2, 0) = xz - wy;

  		result(2, 1) = yz + wx;

  		result(2, 2) = 1 - (xx + yy);

  		return result;

  	}

  	CUDA_CALLABLE matrix_sq<T, 4> toMatrix4(){

  		matrix_sq<T, 4> result;

  	    T wx, wy, wz, xx, yy, yz, xy, xz, zz, x2, y2, z2;

  	    // calculate coefficients

  	    x2 = x + x; y2 = y + y;

  	    z2 = z + z;

  	    xx = x * x2; xy = x * y2; xz = x * z2;

  	    yy = y * y2; yz = y * z2; zz = z * z2;

  	    wx = w * x2; wy = w * y2; wz = w * z2;

  		result(0, 0) = 1 - (yy + zz);

  		result(0, 1) = xy - wz;

  		result(0, 2) = xz + wy;

  		result(1, 0) = xy + wz;

  		result(1, 1) = 1 - (xx + zz);

  		result(1, 2) = yz - wx;

  		result(2, 0) = xz - wy;

  		result(2, 1) = yz + wx;

  		result(2, 2) = 1 - (xx + yy);

  		result(3, 3) = 1;

  		return result;

  	}

  

  

  	CUDA_CALLABLE quaternion(){

  		w=0; x=0; y=0; z=0;

  	}

  

  	CUDA_CALLABLE quaternion(T c, T i, T j, T k){

  		w=c;  x=i;  y=j;  z=k;

  	}

  

  };

  

  }	//end rts namespace

  

  

  #endif