Mapping y deadzone for gamepad thumbstick

mapydeadzone.cpp

float Interpolate( float normalizedValue, float begin, float end )
{
    // first check input values
    assert( normalizedValue >= 0.0f );
    assert( normalizedValue <= 1.0f );
    assert( end > begin );
    
    return ( normalizedValue * ( end - begin ) ) + begin;
}

void MapYDeadZone( Vec3 &input, float deadZone )
{
    if ( deadZone >= 1.0f )
    return;
    
    // The dead zone is assumed to be zero close to the origin
    // so we have to interpolate to find the right dead zone for
    // our current value of X.
    
    float actualDeadZone = Interpolate( fabs( input.x ), 0.0f, deadZone );
    
    if ( fabs( input.y ) < actualDeadZone )
    {
        input.y = 0.0f;
        return;
    }
    
    // Y is outside of the dead zone, but we still need to
    // interpolate it so we don't see any popping.
    
    // Map Y values [ actualDeadZone, 1.0f ] to [ 0.0f, 1.0f ]
    float sign = ( input.y > 0 ) ? 1 : -1 ;
    float normalizedY = ( fabs( input.y ) - actualDeadZone ) / ( 1.0f - actualDeadZone );
    
    input.y = normalizedY * sign;
}