gistfile1.c

    // If we're not inside our current/last rectangle, then we are in the air flying towards our destination, so we should just continue to do that
    if (character->x < current_rect->bottomleft.x || character->x > current_rect->bottomright.x || character->y < current_rect->topleft.y || character->y > current_rect->bottomleft.y)
    {
        // Get the equation of the parabola of our current falling (in the form y = ax^2 + bx + c)
        double a, b, c;
        a = GRAVITY/2;
        b = sqrt(character->hs*character->hs + character->vs*character->vs) - 2*a*character->x;
        c = character->y - a*character->x*character->x - b*character->x;

        // Test whether we'll land within the right boundaries with the current path
        double landing_x;
        // The determinant should always be positive since we will always be above the target (and gravity always points down)
        landing_x = (-b + sqrt(b*b - 4*a*(c-next_rect->bottomleft.y)))/(2*a);
        if (landing_x < next_rect->bottomleft.x)
        {
            // We're overshooting on the left side
            output[DIRECTION] = DIR_LEFT;
        }
        else if (landing_x > next_rect->bottomright.x)
        {
            // We're overshooting on the right side
            output[DIRECTION] = DIR_RIGHT;
        }
        else
        {
            // We're good, but we might get to where-ever faster if we continued moving in the direction we were going until now
            if (character->hs < 0)
            {
                output[DIRECTION] = DIR_LEFT;
            }
            else if (character->hs > 0)
            {
                output[DIRECTION] = DIR_RIGHT;
            }
            else
            {
                output[DIRECTION] = STANDSTILL;
            }
        }
    }