orbital()

VectorField MayaFlux::Kinesis::ForceFields::orbital ( const glm::vec3 &  anchor, const glm::vec3 &  axis, float  strength  )

inline

Tangential force perpendicular to both an axis and the radius vector.

Parameters

anchor	Point the orbit is centred on.
axis	Orbital axis (e.g. glm::vec3(0, 1, 0) for orbits in the XZ plane).
strength	Force magnitude, constant with distance.

Returns

VectorField: glm::vec3 -> glm::vec3

cross(axis, p - anchor) is perpendicular to the radius vector in the plane normal to axis, which is the direction that turns radial motion into revolution rather than a straight collapse or escape. Combine with point_attractor on the same anchor for an orbit: attraction supplies the centripetal pull, this supplies the sideways push that keeps the fall from being straight down. Unlike a true two-body problem this is force-based rather than velocity-constrained, so orbits drift rather than close exactly, which reads as organic rather than as a bug.

Definition at line 46 of file ForceFields.hpp.

{
    return { .fn = [anchor, axis, strength](const glm::vec3& p) -> glm::vec3 {
        glm::vec3 radius = p - anchor;
        glm::vec3 tangent = glm::cross(axis, radius);
        float d = glm::length(tangent);
        if (d < 0.001F)
            return glm::vec3(0.0F);
        return (tangent / d) * strength;
    } };
}

References MayaFlux::Kinesis::Tendency< D, R >::fn, and radius.