cartesian<>Polar

gistfile1.txt

/**
 * converts cartesion to polar coordinates
 * result:
 * [0] = length
 * [1] = angle z-axis rotation [-PI, PI](range) Z軸回転
 * [2] = angle of projection into x,y, plane with x-axis [-PI, PI](range)
 */
static ofVec3f cartesianToPolar(const ofVec3f &v)
{
	ofVec3f polar;
	polar[0] = v.length();

	if (v[2] > 0.0f) {
		polar[1] = (float)atan(sqrt(v[0] * v[0] + v[1] * v[1]) / v[2]);
	}
	else if (v[2] < 0.0f) {
		polar[1] = (float)atan(sqrt(v[0] * v[0] + v[1] * v[1]) / v[2]) + PI;
	}
	else {
		polar[1] = PI * 0.5;
	}
	polar[1] -= PI*0.5;
	if (v[0] > 0.0f) {
		polar[2] = (float)atan(v[1] / v[0]);
	}
	else if (v[0] < 0.0f) {

		polar[2] = atan(v[1] / v[0]);
		if (v[0] < 0 && v[1] < 0)
		{
			polar[2] -= PI;
		}
		if (v[1] / v[0] <= 0)
			polar[2] += PI;
	}
	else if (v[1] > 0) {
		polar[2] = PI * 0.5f;
	}
	else {
		polar[2] = -PI * 0.5;
	}
	return polar;
}
//GLSL
/**
 * converts cartesion to polar coordinates
 * result:
 * [0] = length
 * [1] = angle with z-axis[-PI, PI]
 * [2] = angle of projection into x,y, plane with x-axis[-PI, PI]
 */
vec3 cartesianToPolar (vec3 v)
{
	vec3 polar;
    
    float M_PI = 3.14159265358979323846;
    float HALF_PI = M_PI/2.0;
	polar[0] = length(v);
	
	if (v[2] > 0.0f) {
		polar[1] = atan(sqrt (v[0]*v[0]+ v[1]*v[1])/v[2]);
	}
	else if (v[2] < 0.0f) {
		polar[1] = atan(sqrt(v[0]*v[0]+ v[1]*v[1])/v[2]) + M_PI;
	}
	else {
		polar[1] = M_PI * 0.5f;
	}
	polar[ 1 ] -= HALF_PI;
	if (v[0] != 0.0f) {
        polar[2] = clamp(atan (v[1], v[0]), -M_PI, M_PI);
    }
	else if (v[1] > 0) {
		polar[2] = M_PI * 0.5f;
	}
	else {
		polar[2] = -M_PI * 0.5;
	}
	return polar;
}
/**
 * converts polar to cartesion coordinates
 * input:
 * [0] = length
 * [1] = angle with z-axis
 * [2] = angle of projection into (x,y)-plane
 */
static ofVec3f polarToCartesian (const ofVec3f &v)
{
	ofVec3f cart;
	cart[0] = v[0] * (float) sin (v[1]) *
	(float) cos (v[2]);
	cart[1] = v[0] * (float) sin (v[1]) *
	(float) sin (v[2]);
	cart[2] = v[0] * (float) cos (v[1]);
	return cart;
}