I have a sprite which size changes from 0.6f to 2.0f during an animation.
At the same time I want its alpha value to change from 1.0f to 0 as its scale increase. So the sprite is fully opaque at 0.6f and gradually disappear until the size is 2.0f where it becomes totally transparent.
How do I correlate those values?
spriteBatch.Draw(texture, Vector2.Zero, Color.White*alpha,null,0f,origin,scale,1f);
Where
alpha = MathHelper.Clamp(0, 1 , 1 - (scale - startScale)/deltaScale);
In your case
startScale = 0.6f,deltaScale = 2.0f-0.6f = 1.4f;
It's going to be easier and more expandable if you animate each value separately. In this case scale and alpha, but the same logic could be applied to anything.
Animations are a function of time, so the variable you're missing here is how long you want the animation to last.
Each animation has a startValue and an endValue. From that you can derive 'change per second' like this:
var changePerSecond = (endValue - startValue) / totalSeconds;
Then in each frame, you simply increment the desired property by multiplying by the frame time (deltaTime), e.g.
scale += changePerSecond * deltaTime;
Okay, with the basic concept out of the way you can see how it would work for scale and alpha in your animation (using a 1 second animation as an example).
var scalePerSecond = (2.0f - 0.6f) / 1.0f;
var alphaPerSecond = (0.0f - 1.0f) / 1.0f;
Then in your update method..
scale += scalePerSecond * deltaTime;
alpha += alphaPerSecond * deltaTime;
Note that this is an example of the simplest linear animation off the top of my head to demonstrate the concept. You'll likely need other code to detect the end of the animation and what to do when it finishes.
Related
I'm writing a custom editor window in Unity in which I would like to be able to both scroll in/out and drag the view around. To do so, I've been setting GUI.matrix to Matrix4x4.TRS(offset, Quaternion.identity, Vector3.one * scale), where I have control over offset and scale. This works fine, except when scrolling in/out, it anchors the top left of the window. I would like it to anchor on the mouse's position.
If this just requires changing the offset when zooming, that's great - I'm just not sure what the offset should be here. Matrix4x4s are out of my comfort zone for math.
Here is how I'm currently handling zooming:
if (Event.current.type == EventType.ScrollWheel)
{
_scale *= Math.Sign(Event.current.delta.y) == 1 ? 1.1f : 1f / 1.1f;
_offset += Math.Sign(Event.current.delta.y) * /*What do I put here?*/;
}
Let's try to understand whatthe GUI matrix does. It represents a transform that takes coordinates in world space (where your GUI objects live) and converts them to GUI space (more or less aligned with your window). Since we have no rotation, we can easily interpret what constructing the matrix with TRS() does to a world-space point pWorld:
pGUI = scale * pWorld + offset
Now you want to change scale to scaleNew. In doing so, you want to keep the same world position under the mouse.
If your mouse position is given in GUI space (e.g., from Event.current.mousePosition), then we first need to find the corresponding world space point:
v3World = (1.0 / scaleOld) * (v3GUI - offsetOld)
And we want to fix this point under the mouse, i.e.:
v3GUI = scaleNew * v3World + offsetNew
v3GUI = scaleNew / scaleOld * (v3GUI - offsetOld) + offsetNew
We can solve this to get the new offset:
v3GUI = scaleNew / scaleOld * v3GUI - scaleNew / scaleOld * offsetOld + offsetNew
(1 - scaleNew / scaleOld) * v3GUI + scaleNew / scaleOld * offsetOld = offsetNew
And that's it.
Btw, you can also do this with matrix operations alone. This is what GUIUtility.ScaleAroundPivot() does. This is how it looks:
newMatrix = T(v3GUI) * S(newScale / oldScale) * T(-v3GUI) * oldMatrix
T represents a translation and S a scaling. The translation pair T(v3GUI) and T(-v3GUI) move the temporary origin of the coordinate system to your mouse position and perform the scaling from there. You could then directly read offset and scale from this matrix.
How can I keep the diagonal speed to be the same as the horizontal and vertical speed without clamping any value or using ".normaized". I tryed to normalize the values but I lost the joystick values between 1 and 0. Here is my code :
void ListenInput()
{
Vector3 rightDirection = camera.right;
Vector3 frontDirection = camera.GetForwardFromAngleY();
move = new Vector2(
Input.GetAxis("Horizontal"),
Input.GetAxis("Vertical")
);
MoveCharacter(rightDirection * move.x);
MoveCharacter(frontDirection * move.y);
}
void MoveCharacter(Vector3 velocity)
{
transform.position += velocity * Time.deltaTime * runningSpeed;
}
Here, you should clamp the magnitude of the input Vector2.
For example with Vector2.ClampMagnitude() from the Unity API.
That will keep the input non-binary and prevent the diagonal from getting larger than purely horizontal/vertical inputs.
void ListenInput()
{
Vector3 rightDirection = camera.right;
Vector3 frontDirection = camera.GetForwardFromAngleY();
move = new Vector2(
Input.GetAxis("Horizontal"),
Input.GetAxis("Vertical")
);
move = Vector2.ClampMagnitude(move, 1f);
MoveCharacter(rightDirection * move.x);
MoveCharacter(frontDirection * move.y);
}
void MoveCharacter(Vector3 velocity)
{
transform.position += velocity * Time.deltaTime * runningSpeed;
}
If you normalize a vector you will make sure it's length is 1. This is a great way to avoid quirks like "diagonal movement is faster than normal movement".
However, the fact that the length is always 1 also means that there is no "move slowly" or "move at full speed" distinction from the joystick. When you say "I lost the joystick values between 1 and 0" is due to this fact.
One way developers get around this is by using a mathematical formula to scale the speed.
You could:
Use the largest value (horizontal or vertical) to control the speed
Use the smallest value
Use a combination of the two
Another way to do this is to store how long ago the movement started, then scale the speed based on that. This method has its own challenges, but is very familiar to players.
Examples
For instance, if I have:
horizontalInput = 1
verticalInput = 0.5
This means my normalized vector looks like this:
I could:
Use the largest value
Move at full speed (1) on the direction of my vector.
Use the smallest value
Move at half speed (0.5) on the direction of my vector.
Use a Use a combination of the two values
For this instance, lets use the following formula: (x+y)/2.
Move at 3/4 speed (0.75) on the direction of my vector.
NOTE: This formula will not "feel" as nice if you have x=0 and y=1, this is just an example. You most likely want to use Min, Max, Avg and if-clauses to control how the speed works.
You can use different formulas and different techniques to make the movement in your game feel like what you want, but take the time to analyze WHY it feels like that.
im trying to move a object in unity between 2 points, and at the moment it kinda works strange, i read the documentation and it says that the object begin point is (0,0,0) so my object goes under my other mesh that i have there, and the end point i can actually control, in my case it is 10, i want the object to move between 1.5 and 10(not 0 to 10)
i have this
void Update () {
transform.position = new Vector3(transform.position.x,Mathf.PingPong(Time.time,10.0f), transform.position.z);
}
when i try to put speed on the ball doing this:
void Update () {
transform.position = new Vector3(transform.position.x,Mathf.PingPong(Time.time,10.0f) * 10, transform.position.z);
}
the object does not colide and goes back at the end point it just stop looping and never came back how can i correct this 2 problems?
If your object has a collider, I suggest you move it via its Rigidbody rather than its Transform, to avoid potential collision issues. Try this:
public float MinY = 1.5f; // y position of start point
public float MaxY = 10f; // y position of end point
public float PingPongTime = 1f; // how much time to wait before reverse
public Rigidbody rb; // reference to the rigidbody
void Update()
{
//get a value between 0 and 1
float normalizedTime = Mathf.PingPong(Time.time, PingPongTime) / PingPongTime;
//then multiply it by the delta between start and end point, and add start point to the result
float yPosition = normalizedTime * (MaxY - MinY) + MinY;
//finally update position using rigidbody
rb.MovePosition(new Vector3(rb.position.x, yPosition, rb.position.z));
}
Here you have a better control on the distance to travel, and the speed.
Actually I didn't get exactly what are the problem you faced. But don't forget here and in your try, that you are directly modifying the position of the object, not adding forces or else.
Hope that helps you.
I think you simply misunderstood how the Mathf.PingPong method works :
first argument t is the value you want to "clamp" between 0 and the given length : this is were you want to put the Time.time as you did since this value will increase over time and therefore perpetually oscillate. If you want to increase/decrease the oscillation speed you have to multiply it.
second argument length is the max value of the "clamp" : if you want to increase/decrease the distance (in your case) you have either set it to 0 and multiply the whole Mathf.PingPong(...) by a value or directly give it the wanted value (both implementations will have a different effect.
Mathf.PingPong(Time.time * speed, 1.0f) * value : speed will affect the oscillation speed / value will affect the max value reached AND the speed / time to complete the oscillation (back and forth) will remain the same as value changes and decrease as speed increases
Mathf.PingPong(Time.time * speed, value) : speed will affect the oscillation speed / value will affect the max value reached BUT NOT the speed / time to complete the oscillation (back and forth) will increase as value increases and decrease as speed increases
About your other problems :
If you want to move your object between 1.5 and 10 you have to write something like this :
transform.position = new Vector3(transform.position.x, 1.5f + Mathf.PingPong(Time.time, 10.0f - 1.5f), transform.position.z);.
Also if you want to detect collision, avoid setting position manually as it will mess up with Physics and cause weird behaviors. Best way to move your object while keeping physic working is to do as #Heldap said using Rigidbody.MovePosition.
I have a windows universal app where I am rendering a scene with DirectX. I want to make use of the Scrollviewer and therefore I render my scene behind the Scrollviewer and want to calculate the scene transformation based on the Scrollviewer. It works fine so far, especially the translation and scrolling. But when I zoom in, the scene jumps around in two special situations:
The scene had enough space and was centered and now scrolling is required.
The opposite direction.
More or less I use the following code:
float zoom = scrollViewer.ZoomFactor;
float inverseZoom = 1f / scrollViewer.ZoomFactor;
float scaledContentW = Document.Size.X * scrollViewer.ZoomFactor;
float scaledContentH = Document.Size.Y * scrollViewer.ZoomFactor;
float translateX;
float translateY;
if (scaledContentW < scrollViewer.ViewportWidth)
{
translateX = ((float)scrollViewer.ViewportWidth * inverseZoom - Document.Size.X) * 0.5f;
}
else
{
translateX = -inverseZoom * (float)scrollViewer.HorizontalOffset;
}
if (scaledContentH < scrollViewer.ViewportHeight)
{
translateY = ((float)scrollViewer.ViewportHeight * inverseZoom - Document.Size.Y) * 0.5f;
}
else
{
translateY = -inverseZoom * (float)scrollViewer.VerticalOffset;
}
float visibleX = inverseZoom * (float)scrollViewer.HorizontalOffset;
float visibleY = inverseZoom * (float)scrollViewer.VerticalOffset; ;
float visibleW = Math.Min(Document.Size.X, inverseZoom * (float)scrollViewer.ViewportWidth);
float visibleH = Math.Min(Document.Size.Y, inverseZoom * (float)scrollViewer.ViewportHeight);
Rect2 visibleRect = new Rect2(visibleX, visibleY, visibleW, visibleH);
transform =
Matrix3x2.CreateTranslation(
translateX,
translateY) *
Matrix3x2.CreateScale(zoom);
You can get an example here: https://github.com/SebastianStehle/Win2DZoomTest
To be sure that my eyes are not broken I was zooming around and have written the translation and zoom values to a file. You can see it here:
https://www.dropbox.com/s/9ak6ohg4zb1mnxa/Test.png?dl=0
The meaning of the columns is the following:
Column 1: The computed zoom value of the transformation matrix (M11) = ScrollViewer.ZoomFactor
Column 2: The computed x offset of the matrix (See above)
Column 3: The x value of the result of matrix * vector (500, 500), here: Colum1 * 500 + Column2
You see, that the matrix values look good, but when applying the transformation you get this little jump to the right for some milliseconds. One theory was, that the viewport might change because the scrollbar becomes visible. But this is not the case. I also tried fixed values here, made the scrollbars visible and even created a custom template for the scrollviewer with no scrollbars at all.
Btw: This is a cross post, I also asked the question here: https://github.com/Microsoft/Win2D/issues/125
You see this behavior because when you zoom bigger than the ScrollViewer's size, the zoom center point is moved. To fix this, you just need to subscribe to the ScrollViewer's LayoutUpdated event and inside the handler, manually keep its content in the center.
private void ScrollViewer_LayoutUpdated(object sender, object e)
{
this.ScrollViewer.ChangeView(this.ScrollViewer.ScrollableWidth / 2, this.ScrollViewer.ScrollableHeight / 2, this.ScrollViewer.ZoomFactor, true);
}
This should fix the jumpy movement on the two drawed Rectangles from Win2D.
Update
Just to prove my point, the jumpy behavior is most likely due to unusual translate x and/or y value change when the content size goes over the size of the ScrollViewer. So I wrote some code to log these values on the screen as shown below -
...
this.Test1.Text += ((float)translateX).ToString() + " ";
this.Test2.Text += ((float)translateY).ToString() + " ";
session.Transform =
Matrix3x2.CreateTranslation(
(float)translateX,
(float)translateY) *
Matrix3x2.CreateScale((float)zoom);
Now look at the numbers on the image above. What I did was I tried zooming in until the jumpy scene occurred. See the highlighted translate y value? It is slightly greater than its previous value, which is against the declining trend.
So to fix this, you will need to be able to skip these unusual values caused by ScrollViewer.
Alright, so here's my problem.
I've been trying to create a sort of a visual day/night cycle in XNA, where I have an underlying class that updates and holds time and a Sky class which outputs a background based on the time that the class updates.
What I can't figure out though is how to make the moon/sun move in a curved upward arc that spans the screen based on what time of the day it is. The most problematic part is getting the Y axis to curve while the X axis moves as the time progresses.
Anyone that could help me here?
EDIT:
Alright, looks like Andrew Russels example helped me to do what I needed to do.
Although I had to expermient for a bit, I finally reached a suitable solution:
float Time = (float)Main.inGameTime.Seconds / (InGameTime.MaxGameHours * 60 * 60 / 2);
this.Position.X = Time * (Main.Viewport.X + Texture.Width * 2) - Texture.Width;
this.Position.Y = Main.Viewport.Y - (Main.Viewport.Y * (float)Math.Sin(Time * MathHelper.Pi) / 2) - (Main.Viewport.Y / 2) + 50;
Try looking at the Math.Sin or Math.Cos functions. These are the trigonometric functions you're looking for.
Something like this (giving a position for SpriteBatch):
float width = GraphicsDevice.Viewport.Width;
float height = GraphicsDevice.Viewport.Height;
float time = 0.5f; // assuming 0 to 1 is one day
Vector2 sunPosition = new Vector2(time * width,
height - height * (float)Math.Sin(time * width / MathHelper.TwoPi));
(Disclaimer: I haven't tested this code.)
There is also the Curve class.