Develop Reference

How to remap mouse position to a potentially moving UI element?

I'm working on an RTS game with some pretty extensive UI, so I moved the main camera's output to a quad which only makes up about half the screen, and I'm blitting some UI effects over the rest. My current way of interacting with the game uses unity's Input.mousePosition. When I moved the camera's feed to the quad, obviously those pixel coordinates were distorted, so I fixed them like this:
mapMousePos = (Input.mousePosition * mscaleCorr - mapCorrection * mscaleCorr);
mapCorrection being the pixel offset of the smaller feed, and mscaleCorr being a magic number that got through trial and error — a temporary fix.
Point is, now I'm realizing that running this game at a different resolution will almost certainly break these magic numbers.
What I want mapMousePos to be is what Input.mousePosition was before I moved the gameplay to the small quad - going from (0,0) in the bottom left of the quad to the screen (width, height) in the top right of the quad. This is just so it works with screenToWorld point really nicely on my gameplay camera.
I have the camera-feed quad parented to a full-screen quad, and tried using their relative positions to apply the necessary transformations, but it didn't work, I'm guessing because it's a pixel problem.
I've dug around the docs for a solution using Camera's builtin worldToScreenPoint function, without any luck. I'm sure I'll bump into a fix eventually, but would greatly appreciate any pointers.

Here's what I've come up with; it's stupid, but it works.
I've placed objects at the bottom left and top right of the quad, stored in code as bL and tR.
Then I convert the mousePosition to a worldPosition using ScreenToWorldPoint(), remap it by subtracting the bottom left position, and get it as a percentage across the screen by dividing it by the delta to the top right. Multiply the percentage by the pixel dimensions of the gameplay camera, and voila.
In code, this:
Vector3 wPos = finalcam.ScreenToWorldPoint(Input.mousePosition);
wPos -= bL.transform.position;
mapMousePos = new Vector2(Mathf.Abs(wPos.x), Mathf.Abs(wPos.y));
mapMousePos = new Vector2(
mapMousePos.x / (tR.transform.position.x -bL.transform.position.x),
mapMousePos.y / (tR.transform.position.y - bL.transform.position.y));
mapMousePos = new Vector2(mapMousePos.x * Camera.main.pixelWidth, mapMousePos.y * Camera.main.pixelHeight);
Again, it's dumb, but it seems to work. I'm leaving this up in case anybody knows a cleaner method.

Problem with Scale matrix in canvas scene and mouse position [WinForms]

After applying a scale matrix to my scene of drawable objects, the actual position in the mouse cursor scene is incorrect.
In my opinion the problem is caused by the location gave me from the event of control (mousedown,up,and move) that is not faithful to my scene geometry.
var matrix = this.Control.Scene.Matrix.Inverse();
this.CoordsLabel.Text = matrix.MultiplyPoint(e.Location).ToString()
When i m very zoommed in my scene, "matrix.MultiplyPoint(e.Location)" return the same value for a short mouse movement. The other operation like translation, rotation works fine.
Example Image:
Here, The cursor is perfectly adjacent to the gray cross drawn
Here, This is very zoom situation, the cursor is not over the gray cross line, and for small mouse movement the gray line not change, as if the multiplication with scene matrix give me the same value of coord. (matrix.MultiplyPoint(e.Location))
Please hel me with this problem.
Thanks a lot.

How do I convert point to local coordinates?

when a user taps a button I want the tap to be ignored if a transparent pixel is hit and the button beneath it should receive the tap instead.
I can do this sort of behaviour in objective c within a few minutes, however, trying to do it in Unity in C# has proven impossible as there is no way to convert a point from the screen to a local point. Obviously either the center or the bottom left, or the top left corner should be the origin point (I don't know which because Unity continuously changes where the origin is depending on the phase of the moon)
I've tried looking at the IsRaycastLocationValid from the ICanvasRaycastFilter
and inside I've used both RectTransformUtility.ScreenPointToLocalPointInRectangle and RectTransformUtility.ScreenPointToWorldPointInRectangle and the result is always the same. The RectTransform I give is the one belonging to the button.
eg:
public bool IsRaycastLocationValid(Vector2 screenPosition, Camera raycastEventCamera) //uGUI callback
{
Vector2 localPoint;
RectTransformUtility.ScreenPointToLocalPointInRectangle(rectTransform, screenPosition, null, out localPoint);
Vector2 pivot = rectTransform.pivot - new Vector2(0.5f, 0.5f);
Vector2 pivotScaled = Vector2.Scale(rectTransform.rect.size, pivot);
Vector2 realPoint = localPoint + pivotScaled;
Debug.Log(screenPosition + " " + localPoint);
return false;
}
Which I got from someone else's unanswered attempt here
Unity 3d 4.6 Raycast ignore alpha on sprite
I've found this link
http://forum.unity3d.com/threads/alpha-area-on-round-gui-button-return-click-event.13608/
where someone tries to determine if the mousePosition is within the image bounds. The obvious problem being that the image has to have some corner at (100,100). Magic numbers are bad and trying to figure out how to get those coordinates is next to impossible.
The following properties on RectTransform is always the same no matter where you place the button:
anchoredPosition
anchoredPosition3D
anchorMax
anchorMin
offsetMax
offsetMin
pivot
rect
sizeDelta
as you can see, that is all the properties a RectTransform has. Therefore it is impossible to tell where a button is, and is impossible to tell where a click is in the button's coordinate space.
Can someone please tell me how to do what I need to do?

Should do the trick:
bool isScreenPointInsideRectTransform( Vector2 screenPoint, RectTransform transform, Camera canvasCamera )
{
Vector2 localPoint;
RectTranformUtility.ScreenPointToLocalPointInRectangle( transform, screenPoint, canvasCamera, out localPoint );
return transform.rect.Contains( localPoint );
}

Thats exactly why you dont find the location of the point inside of the button itself... but you compare the location of the point inside of the parent rect of the button and the buttons localPosition itself.
That or you can translate the pixel point to screen position then compare with mouse position

ILNumerics zoom selection rectangle and accessing the plotted data in ILPlotcube

I plot a surface in a Plot Cube with TwoDMode = true, when I try to zoom using the mouse left drag, the selection zoom rectangle goes behind the surface, therefore, it is not properly shown. Is it possible to force the selection rectangle to be on top of the surface? Moreover, is it possible by hovering or clicking the mouse on the surface, the X, Y and Z values be shown in some textboxes? Thank you very much.

Surfaces are inherently 3D objects. By default, they are intended to be used with ILPlotCube.TwoDMode set to false. But you can try to access the selection rectangle object and modify it accordingly. Try starting with plotCube.ZoomRectangle.Lines.Positions by raising its Z coordinate in order to move it closer to the camera.
Archieving the point of the surface under the cursor is not easy - but doable. Keep in mind, only the vertices of the surface tiles are known explicitly. You can use picking and the mouse events to get informed, if the mouse is over the surface:
surface.MouseMove += (_s,_a) => { yourHandler(_a); }
Afterwards, you are on your own. First, you will have to find the actual surface 3D coordinates. If you can be sure that the surface has not been rotated, you can take a look here.
The method in that thread gives you the surface X and Y coordinates. You can go further and (manually) find the corresponding tile for that position. For the final and exact X,Y,Z coordinates, you would have to interpolate the tile (triangle) vertices to the actual mouse position, using barycentric interpolation.
In order to show the 3D coordinate, you can simply use an ILLabel. You may or may not want to put that into an ILScreenObject.

Scale Sprite up and Down to give illusion of a jump

I have some code that I wrote that works, but I feel it could be better and wanted to get some feedback.
The goal I had is to have a Sprite Scale up and back down in a timely fashion when a button is pushed so that it gives the illusion of jumping in a "Top Down" view of the game. Like the character is jumping off the screen. I already know how to draw scaled images I'm more interested in the logic of the timing aspect.
This works, just not sure it's the best. Thought maybe there was some equation, a math friend told me maybe a linear equation or like a parabola or second order equation. Not being great with math.
Anyway.
Class Properties
private double _jumpingStartedAt;
private double _totalJumpTimeInSeconds = 0.7;
private double _totalJumpFrames = 14;
private double _timeSinceLastScale;
private double _jumpingHalfWayAt;
When button is pushed for the first time I start the "Jump Logic". This runs once per jump. My thought was that I'd mark the "start" time and determine the "halfway" time by the totalJumpTimeInSeconds.
_jumpingStartedAt = gameTime.TotalGameTime.TotalSeconds;
_jumpingHalfWayAt = _jumpingStartedAt + MillisecondsBetweenFrame() * (_totalJumpFrames / 2);
And then this is run on each Update() until my "jump" is complete or isJumping = false. The logic here is that I would scale up every 1 "frame" until half way point then scale back down.
_timeSinceLastScale += gameTime.ElapsedGameTime.TotalSeconds;
if (_timeSinceLastScale > MillisecondsBetweenFrame() && gameTime.TotalGameTime.TotalSeconds < _jumpingHalfWayAt)
{
Scale += 0.2f;
_timeSinceLastScale = 0;
}
else if (gameTime.TotalGameTime.TotalSeconds > _jumpingHalfWayAt)
{
Scale -= 0.2f;
if (Scale < 1.0) Scale = 1; //probably don't need this was worried if it went passed 0
if (Scale == 1.0) _isJumping = false;
}
private double SecondsBetweenFrame()
{
return _totalJumpTimeInSeconds / this._totalJumpFrames;
}
Now this works, but seems a little convoluted to me.

Stretching image when jumping - side view
Yeah, it's pretty complicated, what you created.
I assume your sprite is also moving up and down when jumping. That you have some sort of Vector2 velocity, which you change by dv = gravityAcceleration * dt in every update, and so you change Vector2 position by dp = velocity * dt. If so, I would rather use my velocity.Y value to calculate how the sprite should stretch. I think it's more natural. And your code will become much more simple.
Here's an image to describe better what I mean:
However, you can probably face the other problem here: just at the beginning of the jump your sprite will suddenly get high velocity, when still being near the ground, which can cause it to cross through the floor for a moment. To prevent that you can artificially move your sprite upwards by the smallest needed value for the time of jump. The problem is described by the image below:
As you can very well see, the first stretched ball moved upwards a little bit, but not enough. You have to calculate difference between sizes before and after stretching and then move your sprite up by that distance.
If you do it like that, your Update should shorten to just a few lines. I believe you can do simple calculations on your own.
Easier approach
...Unless you'd rather like your sprite behave like you want. Then you could modify scale according to your Y position:
if (KeyboardState.IsKeyDown(Keys.Space))
{
isJumping = true;
jumpStartPosition = Position;
}
if (!isJumping) Scale = 1f;
else
{
Scale = StretchFactor * (Position.Y - jumpStartPosition.Y);
}
where:
- isJumping is a bool,
- jumpStartPosition is a Vector2,
- Position is a Vector2 property of your sprite,
- StretchFactor is a float property of your sprite telling how much does it stretch.
And you also need to have end-of-jump condition - for example when the sprite's Position.Y becomes smaller than the jumpStartPosition.Y. But generally this solution (as well as yours) has one disadvantage - there will be problems, if you will want to start jump from one height, and end it on another:
so I would rather recommend my first solution. There you can make stop-jump condition by collision check.
Stretching image when jumping - top-down view
Bummer. Since originally it wasn't specified that it is a top-down game, like those first GTA's, I really misunderstood the question, so the answer doesn't fit much. So the answer goes now.
If you wan't it to be realistic, you should use some basic principles of perspective. As we look at the character jumping from the top, it goes closer to us, so it's image grows. Why's that? Look at the pic below.
There are two things, that are needed for perspective to work: the center of perspective and the screen. The center of perspective is the point, where all "rays" are crossing. "Ray" is a line from the any point in the world to the center of our eye. Now the screen is the plane, where image of 3d world is being created. The points of the real world are being cast into screen along their rays. Of course your game is pseudo-3d, but it shouldn't matter in that case.
When z grows, sprite comes closer to the center of perspective. If you imagine ray from the center of perspective to the edge of the sprite, the angle of ray changes, as it's distance to the center of perspective becomes lesser. And the change of angle makes the point's image on the screen moving. That's why image grows, or becomes smaller.
Now we can wonder: ok, how now put this into numbers? Look at the picture below:
I deliberately translated whole world by -C so the z coord of the center of perspective could become 0. That makes calculations simplier. What are we trying to find, is the x' - coord of the point on the screen. Let the Z* = |z - C|. If we look at this picture it becomes clear, that we can find what we need by pretty simple proportion:
Using the same method you can calculate y'. If your character is always at the center of the screen, all that you need will be x'/x = y'/y = S, i.e. your scale. That's because x in this scenario is, in fact, the half-width of the sprite, and y is the half-height. However, if your character will be able to move freely around the screen, you may want to scale & translate it, so it would be more natural:
The white square is the on-the-ground sprite, the gray square is the jumping sprite. In this case you will have to know l (left), r (right), t (top) and b (bottom) coords of the sprite's boundaries (top-bottom means Y-axis, not Z-axis). Then using the same proportion you can get l', r', t' and b' - boundaries of the sprite's image on screen. From this data you should be able to calculate both scale and translation.
Note: L is the parameter of our calculation which you have to choose yourself. Assuming, that the screen has constant width Ws and height Hs, L strictly corresponds with FOV (field of view). You can acquire it also using proportions. So L = (cos(FOV/2) * Ws)/2. I would recommend FOV = 60 deg. If you will make FOV too big, you may face the fisheye problem.