axis_fraction()

std::function< float(glm::vec2)> MayaFlux::Kinesis::axis_fraction ( AABB2D  bounds, float  handle_extent = 0.F, bool  horizontal = true, const std::function< glm::vec2()> &  live_offset = {}  )

inlinenoexcept

Fraction along one axis of bounds, inverse to fader placement.

horizontal_fader and vertical_fader place the handle's leading edge at min + value * (extent - handle_extent), so the handle centre travels a span shorter than the track by one handle. This subtracts half a handle before dividing by the reduced span, so the handle centre tracks the cursor across the whole range rather than lagging by up to half a handle at the extremes.

Pass handle_extent of zero for mappings with no handle inset, such as a level_meter used as a scrub region.

Parameters

bounds	Track region in NDC.
handle_extent	Handle width for horizontal, height for vertical.
horizontal	True to map the x axis, false for y.
live_offset	Optional. Current translation of the drawn control, e.g. a Scrollable's live scroll offset.

Returns

Callable producing a value in [0, 1].

Definition at line 49 of file Projection.hpp.

                                                {}) noexcept
{
    const float extent = horizontal ? bounds.width() : bounds.height();
    const float span = extent - handle_extent;
    const float origin = horizontal ? bounds.min.x : bounds.min.y;
    const float half = handle_extent * 0.5F;
 
    return [origin, half, span, horizontal, live_offset](glm::vec2 p) -> float {
        if (span <= 0.F)
            return 0.F;
        const float shift = live_offset ? (horizontal ? live_offset().x : live_offset().y) : 0.F;
        const float pos = (horizontal ? p.x : p.y) - shift;
        return std::clamp((pos - origin - half) / span, 0.F, 1.F);
    };
}

Referenced by MayaFlux::Portal::Forma::Geometry::horizontal_fader(), and MayaFlux::Portal::Forma::Geometry::vertical_fader().

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