UNITY Draw rectangle on mouse drag

Question

What's the proper way of drawing rect outline based on mouse hover. Effect you get in strategy games when selecting units. Running Unity 2018.3.0f. Perhaps my code can be slightly changed. I was unable to find something done. As second option I could use LineRenderer and create a rect based on that line. Adding lines that would make the rect.

This is an example:

This is what I came up with but for some reason this has wrong Y coords.

using UnityEngine;
using System.Collections;
using System;

public class MouseDragSelect : MonoBehaviour
{

    private Rect position = new Rect(193, 148, 249-193, 148-104);
    public Color color = Color.green;
    private Vector3[] mousePositions = new Vector3[2];
    private bool draggingMouse = false;
    private bool drawRect = false;
    public float timer = 1.2f;

    void OnGUI()
    {
        if (drawRect)
        {
            DrawRectangle(position, 1, color);
        }
    }

    void DrawRectangle(Rect area, int frameWidth, Color color)
    {
        //Create a one pixel texture with the right color
        var texture = new Texture2D(1, 1);
        texture.SetPixel(0, 0, color);
        texture.Apply();

        Rect lineArea = area;
        lineArea.height = frameWidth; //Top line
        GUI.DrawTexture(lineArea, texture);
        lineArea.y = area.yMax - frameWidth; //Bottom
        GUI.DrawTexture(lineArea, texture);
        lineArea = area;
        lineArea.width = frameWidth; //Left
        GUI.DrawTexture(lineArea, texture);
        lineArea.x = area.xMax - frameWidth;//Right
        GUI.DrawTexture(lineArea, texture);
    }

    void reset() {
        drawRect = false;
        mousePositions[0] = new Vector3();
        mousePositions[1] = new Vector3();
        timer = 1.2f;
        draggingMouse = false;
    }
    private void Update()
    {
        if (drawRect)
        {
            if (timer > 0.1)
            {
                timer -= 1 * Time.deltaTime;
            } else {
               reset();
            }
        }
        if(Input.GetMouseButtonDown(0)) {
            if(!draggingMouse){
                mousePositions[0] = Input.mousePosition;
                print("x start:" + mousePositions[0].x);
                print("y start:" + mousePositions[0].y);
            }
            draggingMouse = true;
        }
        if(Input.GetMouseButtonUp(0)) {
            if(draggingMouse) {
                mousePositions[1] = Input.mousePosition;
                float width = Math.Abs(mousePositions[1].x - mousePositions[0].x);
                float height = Math.Abs(mousePositions[1].y - mousePositions[0].y);
                float x = mousePositions[0].x;
                float y = mousePositions[0].y;
               // print("width:" + width);
               // print("height:" + height);
                print("x end:" + mousePositions[1].x);
                print("y end:" + mousePositions[1].y);
                position = new Rect(x, y, width, height);
               // print("Got last mouse position!");
                drawRect = true;
            }
        }
    }
}

Tried selecting area around the character.. Getting weird Y coords..

Following solutions does not work either :( as I am getting weird Y coords

            float x = Math.Min(mousePositions[0].x, mousePositions[1].x);
            float y = Math.Min(mousePositions[0].y, mousePositions[1].y);
            float width = Math.Max(mousePositions[0].x, mousePositions[1].x) - x;
            float height = Math.Max(mousePositions[0].y, mousePositions[1].y) - y;

Answer 1

so for your y coord, screen space and world space are different frommouse to screen. change your y to Screen.height-mousePosition.y. this will fix it for you

Answer 2

GL.LoadPixelMatrix提供了简单而适当的工作流程来完成此任务。