angle_fraction() [2/2]

std::function< float(glm::vec2)> MayaFlux::Kinesis::angle_fraction ( glm::vec2  center, float  angle_start, float  angle_end  )

inlinenoexcept

Fraction along an angular sweep about center.

Inverse to radial, which places the indicator at angle_start + value * (angle_end - angle_start). Handles sweeps in either direction and sweeps crossing the atan2 discontinuity. The cursor's distance from the centre is ignored, so the control remains responsive outside the drawn radius, which is what a knob gesture expects.

Points at the exact centre return zero rather than an undefined angle.

Parameters

center	Sweep centre in NDC.
angle_start	Angle in radians corresponding to value 0.
angle_end	Angle in radians corresponding to value 1.

Returns

Callable producing a value in [0, 1].

Definition at line 90 of file Projection.hpp.

{
    const float delta = angle_end - angle_start;
 
    return [center, angle_start, delta](glm::vec2 p) -> float {
        constexpr float k_two_pi = 6.283185307179586F;
 
        if (std::abs(delta) < 1e-6F)
            return 0.F;
 
        const glm::vec2 d = p - center;
        if (glm::dot(d, d) < 1e-12F)
            return 0.F;
 
        float rel = std::fmod(std::atan2(d.y, d.x) - angle_start, k_two_pi);
        if (delta > 0.F && rel < 0.F) {
            rel += k_two_pi;
        } else if (delta < 0.F && rel > 0.F) {
            rel -= k_two_pi;
        }
 
        return std::clamp(rel / delta, 0.F, 1.F);
    };
}

Referenced by angle_fraction(), and MayaFlux::Portal::Forma::Geometry::radial().

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