How to make efficient movement handling

Question

I am developing a "game engine" (with Processing's core.jar as a library) to use for a future game, and have got some basic structure setup, however I have tried testing creating a moving player and realized that the movement handling I have created is embarrassing and it also doesn't function perfectly. For example, the diagonal speed is just a guess, and the whole thing is just feels unnecessarily bloated.

@Override
public void update(Entity entity, double delta)
{
    if (movingLeft && movingUp && movingRight)
    {
        entity.setY((entity.getY() - 3.0f) * (float) delta);
    }
    else if (movingUp && movingRight && movingDown)
    {
        entity.setX((entity.getX() + 3.0f) * (float) delta);
    }
    else if (movingRight && movingDown && movingLeft)
    {
        entity.setY((entity.getY() + 3.0f) * (float) delta);
    }
    else if (movingDown && movingLeft && movingUp)
    {
        entity.setX((entity.getX() - 3.0f) * (float) delta);
    }
    else if (movingUp && movingRight)
    {
        entity.setX((entity.getX() + 2.0f) * (float) delta);
        entity.setY((entity.getY() - 2.0f) * (float) delta);
    }
    else if (movingRight && movingDown)
    {
        entity.setX((entity.getX() + 2.0f) * (float) delta);
        entity.setY((entity.getY() + 2.0f) * (float) delta);
    }
    else if (movingDown && movingLeft)
    {
        entity.setX((entity.getX() - 2.0f) * (float) delta);
        entity.setY((entity.getY() + 2.0f) * (float) delta);
    }
    else if (movingLeft && movingUp)
    {
        entity.setX((entity.getX() - 2.0f) * (float) delta);
        entity.setY((entity.getY() - 2.0f) * (float) delta);
    }
    else if (movingUp)
    {
        entity.setY((entity.getY() - 3.0f) * (float) delta);
    }
    else if (movingRight)
    {
        entity.setX((entity.getX() + 3.0f) * (float) delta);
    }
    else if (movingDown)
    {
        entity.setY((entity.getY() + 3.0f) * (float) delta);
    }
    else if (movingLeft)
    {
        entity.setX((entity.getX() - 3.0f) * (float) delta);
    }
}

How could I optimize this? It would be useful if I knew how to create a better movement system for the future when I do create a game, especially since I already have an idea in mind and want to start working with this engine as soon as it is "usable enough" to start my game.

Answer 1

How about creating 2 direction variables for X and Y?

public void update(Entity entity, double delta) {
    int directionX = 0;
    int directionY = 0;

    if (movingLeft) directionX -= 1;
    if (movingRight) directionX += 1;
    if (movingUp) directionY -= 1;
    if (movingDown) directionY += 1;

    if (directionX != 0 && directionY != 0) {
        // move in both direction
        entity.setX((entity.getX() + 2.0f * directionX) * (float) delta);
        entity.setY((entity.getY() + 2.0f * directionY) * (float) delta);
        return;
    }

    // move in one direction or not moving
    entity.setY((entity.getY() + 3.0f * directionY) * (float) delta);
    entity.setX((entity.getX() + 3.0f * directionX) * (float) delta);
}