Unity RTS Multiple Selection Approacah

Question

I've recently solved the single selection problem but now I want to do multiple selections. I know I need to find two points with the mouse position to draw a box but it just won't work for me.

    void Update()
    {
        if (Input.GetMouseButtonDown(0))
        {
            bool dragging = true;
            Debug.Log("Multiselect active");
            MultiSelect(dragging);
        }
    }
    private void MultiSelect(bool dragging)
    {

        mouseDownPoint = Input.mousePosition;
        if (Input.GetMouseButtonUp(0) && dragging)
        {
            mouseUpPoint = Input.mousePosition;
        }
        Debug.Log("First pos: " + mouseDownPoint + " Second pos: " + mouseUpPoint);
        dragging = false;


    }

What is a better way to achieve what I'm trying? If someone can tell me a way that can also detect any units inside the area that'd be nice too.

Answer 1

You get the start point and end point but you also want to calculate the height and width.

public class CameraSelections : MonoBehaviour
{
public static Rect selection = new Rect(0, 0, 0, 0);
private Vector3 startClick = -Vector3.one;
public Texture2D selectionHighLight = null;

private void LateUpdate()
{
    StartDrag();
}
private void StartDrag()
{
    if (Input.GetMouseButtonDown(0))
        startClick = Input.mousePosition;
    else if (Input.GetMouseButtonUp(0))
        startClick = -Vector3.one;

    HandleSelectionArea();
}
void HandleSelectionArea()
{
    if (Input.GetMouseButton(0))
    {
        selection = new Rect(startClick.x, Screen.height - startClick.y, Input.mousePosition.x - startClick.x, (Screen.height - Input.mousePosition.y) - (Screen.height - startClick.y));
        if (selection.width < 0)
        {
            selection.x += selection.width;
            selection.width = -selection.width;
        }
        if (selection.height < 0)
        {
            selection.y += selection.height;
            selection.height = -selection.height;
        }
    }
}
private void OnGUI()
{
    if (startClick != -Vector3.one)
        GUI.DrawTexture(selection, selectionHighLight);
}

}

then in your player or selectable you can set the Selected bool to true if the selectable is inside the Rect

public class Player : MonoBehaviour
{
public bool Selected=false;
void Update()
{
    if (Input.GetMouseButton(0))
    {
        Vector3 camPos = Camera.main.WorldToScreenPoint(transform.position);
        camPos.y = Screen.height -camPos.y;

        //if inside the cameras drag selection area then mark player as selected
        Selected = CameraSelections.selection.Contains(camPos);        
    }
}
}