Function ticks_alpha

Gui/ticks.cpp:175–184

compute alpha value for drawing the ticks

// compute alpha value for drawing the ticks
double
ticks_alpha(double min,
            double max,
            double val)
{
    assert(val > 0. && min > 0. && max > 0. && max > min);
    const double alpha = sqrt( (val - min) / (max - min) );

    return std::max( 0., std::min(alpha, 1.) );
}