koobas.hobune.stream
What is the mathematical formula for GUI dragging ?
Hi , when working with unity's GUI , there is a formula which is used when creating a drag behavior for GUI.Box, GUI.Button, GUI.DrawTexture etc....
I want to be able to drag any GUI no matter where on the GUI i click and drag . I just wrote this here but this code should do that . The problem is , my drag formula is wrong .
for example
public class DragSomething: EditorWindow
{
private Rect DrawTextureRect = new Rect(0, 0, 50, 50); // reck of gui we will drag
private bool Dragging ; // bool to check if we are dragging ...if mouse is down
private float Xpos, Ypos, Xwidth, Yheight; // so that we can work with each value
private Rect GUIposition(Vector2 mousePosition,Rect guiRect)
{
// our bad math formula which will drag our gui but actually just throws the gui into a corner ... literally
Xpos = mousePosition.x - DrawTextureRect.x; // if we had 540 as mousePosition.x and 500 as DrawTextureRect.x , Xpos would be equal to 40 ... which is very bad
Ypos = mousePosition.y - DrawTextureRect.y; // same here
Xwidth = DrawTextureRect .width;// this is fine
Yheight = DrawTextureRect .height;// this is fine too
return(new Rect(Xpos, Ypos, Xwidth, Yheight));
}
void OnGUI()
{
if (Event.current.type == EventType.MouseUp)
{
Dragging = false;
}
if (Event.current.type == EventType.MouseDown && DrawTextureRect.Contains (Event.current.mousePosition))
{
Dragging = true;
}
if(Dragging )
{
GUIposition(Event.current.mousePosition,DrawTextureRect); // give it the mouse position and the rect of the bui we want to drag
}
}
GUI.DrawTexture(DrawTextureRect,sometexture);
}
one thing I see is, you keep using the current mouse position, even after a drag is started- I'd think you would want to use an OFFSET from the drag start position(which you would need to record).
When you capture mouse down in your Rect, find out how far you away from the Rects origin in x and y, then capture the mouse and subtract the x and y you found. Like what Glurth said.
Try this:
Make a Vector2 called cursorOffset.
Place this where you have Dragging = true, before it.
cursorOffset.x = Event.current.mousePosition.x - DrawTextureRect.x;
cursorOffset.y = Event.current.mousePosition.y - DrawTextureRect.y;
Then your math would be:
Xpos = Event.current.mousePosition.x - cursorOffset.x;
Ypos = Event.current.mousePosition.y - cursorOffset.y;
I think that might work.
also works . I guess the formula comes in different forms but it is essentially always the same .
I was given an example of offset usage which i had been unaware of
using UnityEngine;
using System.Collections;
using UnityEditor;
public class TestWindow : EditorWindow {
[MenuItem ("Window/Test Window")]
static void Init () {
// Get existing open window or if none, make a new one:
TestWindow window = (TestWindow)EditorWindow.GetWindow (typeof (TestWindow));
window.Show();
}
Texture2D pixel;
Rect windowRect;
bool isDragging;
Vector2 offset;
public TestWindow()
{
pixel = new Texture2D(1, 3, TextureFormat.ARGB32, true);
pixel.SetPixel(0, 0, new Color(1, 1, 1, 1));
pixel.Apply();
windowRect = new Rect(10,10,100,100);
isDragging = false;
offset = Vector2.zero;
}
void OnGUI()
{
//update
Event evt = Event.current;
switch(evt.type)
{
case EventType.MouseDown:
if(windowRect.Contains(evt.mousePosition))
{
isDragging=true;
//get offset from mouse
offset = evt.mousePosition - windowRect.position;
}
break;
case EventType.MouseUp:
isDragging = false;
break;
case EventType.MouseDrag:
if(isDragging)
{
windowRect.position = evt.mousePosition - offset;
}
break;
}
//render
GUI.DrawTexture(windowRect,pixel);
Repaint ();
}
