const float uf = ((2.f * ei) / ew - 1.f) * scale;
const float vf = ((2.f * j) / eh - 1.f) * scale;
- const float phi = M_PI + atan2f(vf, uf * m);
- const float theta = m * M_PI_2 * (1.f - hypotf(uf, vf));
+ const float h = hypotf(uf, vf);
+ const float lh = h > 0.f ? h : 1.f;
+ const float theta = m * M_PI_2 * (1.f - h);
- const float sin_phi = sinf(phi);
- const float cos_phi = cosf(phi);
const float sin_theta = sinf(theta);
const float cos_theta = cosf(theta);
- vec[0] = cos_theta * cos_phi;
- vec[1] = cos_theta * sin_phi;
+ vec[0] = cos_theta * uf / lh;
+ vec[1] = cos_theta * -vf / lh;
vec[2] = sin_theta;
normalize_vector(vec);