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Spin Control in Windows Form

I have a picturebox with an image in it. The image contains two ellipses face to face (black & blue).
What I want is to rotate the picturebox in a timer (for the effect) so the image to be "upside down" would look much more like they've changed place, which basically it's just rotating the picturebox like how the erath is moving around it's axis.

There are various kinds of rotations from a globe, depending on how you look at it.
If you look at it from above the poles it spins like a disk or a gear and you can find code for it here. This has the advantage that you can use any image and rotate it.
If you look at it from the side, facing the equator you can't easily use bitmaps, but using just two colors it will still look nice..
Here is an example of a 'globe-like' spinning rotation:
float angle = 0f;
float aSpeed = 4f; // <-- set your speed
Brush brush1 = Brushes.CadetBlue; // and your..
Brush brush2 = Brushes.DarkSlateBlue; // ..colors
private void timer1_Tick(object sender, EventArgs e)
{
angle += aSpeed;
if (angle + aSpeed > 360)
{
angle -= 360f;
Brush temp = brush1;
brush1 = brush2;
brush2 = temp;
}
pictureBox1.Invalidate();
}
private void pictureBox1_Click(object sender, EventArgs e)
{
timer1.Enabled = !timer1.Enabled;
}
private void pictureBox1_Paint(object sender, PaintEventArgs e)
{
e.Graphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;
Rectangle r = pictureBox1.ClientRectangle;
Rectangle r2 = r; // see below..
r.Inflate(-20, -20); // a little smaller than the panel or pBox
if (angle < 180)
{
e.Graphics.FillEllipse(brush1, r);
e.Graphics.FillPie(brush2, r, 270, 180);
r.Inflate(-(int)(r.Width * angle / 360f), 0);
e.Graphics.FillEllipse(brush2, r);
}
else
{
e.Graphics.FillEllipse(brush2, r);
e.Graphics.FillPie(brush1, r, 90, 180);
r.Inflate(-(int)(r.Width * angle / 360f), 0);
e.Graphics.FillEllipse(brush1, r);
}
}
}
This is created by three DrawXXX calls: a circle of one color and an ellipse and an arc, set to display a half circle of the same, second color.
Note: To make the angular speed uniform you may want to play with a little Math.Sin and/or an angle table..
If you look at it from any other angle and if you need to show rotating bitmaps in 3D you can't easily draw it but will need to resort to displaying frames..
But you can combine the disk rotation from the link with the code above and will get rather complex rotations, that look a lot like a 3D sphere.. Simply add the code before the drawing..
float bw2 = r2.Width / 2f;
float bh2 = r2.Height / 2f;
e.Graphics.TranslateTransform(bw2, bh2);
e.Graphics.RotateTransform(angle / 3);
e.Graphics.TranslateTransform(-bw2, -bh2);
..use the drawing from above instead of the DrawImage line and move the ResetTransform to the end. You will want to use a different or scaled angle!

Tooltip in PictureBox FillPie Coordinates C#

I'm drawing a Circle made of 360 FillPie. Each FillPie color is taken from a List. I want to return a string that says at which degree is the mouse and how much is the value of the list to put it on a tooltip.
List<int> datiDisco = new List<int>();
public void Paint (Graphics grafica)
{
try
{
for (int i = 0; i < datiDisco.Count; i++)
{
Brush penna = new SolidBrush(Color.FromArgb(255, ScalaGrigi(valori[i]), ScalaGrigi(valori[i]), ScalaGrigi(valori[i])));
grafica.FillPie(penna, 0, 0, 400, 400, i, 1.0f);
}
}
catch
{
}
}
until here the code is working and i managed to draw the circle with the correct color.Now i can't figure out how i can take the coordinate of each fillpie that i have drawn. Can someone help me?

Figuring out which pie segment the mouse cursor lies in is a simple application of trigonometry, specifically an application of the inverse tangent (aka arctangent or atan).
As a quick reminder for those who've encountered this before, or as a lesson for those who haven't, let's look quickly at the tangent function. Trigonometry deals with the geometry of right triangles, and by definition a right triangle has two sides and a hypotenuse. The hypotenuse is a special name for the side of the triangle opposite the right (90° or π/2) angle. The other two sides are helpfully just called sides.
The tangent function's value is the ratio of the side opposite an angle to the side adjacent to that angle. The arctangent is the angle whose tangent is equal to that ratio. Because of the symmetry of the function we need to calculate the angle, and then add or subtract an offset depending on the quadrant to extract the 'real' angle. In diagram form this looks like:
The tangent function has discontinuities at several points, namely when the adjacent side's length is 0 (90° and 270°), so we'll have to treat those points specially.
OK, enough math, now on to the practical application.
For this demo, create a new C# WinForms project, and on the default Form1 add a PictureBox.
First, since I don't have your color generation function, I use the following list of values and helper function:
List<int> values = Enumerable.Range(0, 360).ToList();
int Rescale(int x) => (int)(((double)x / 360.0) * 255.0);
In the constructor hook up a couple events, and set some properties:
public Form1()
{
InitializeComponent();
this.pictureBox1.BorderStyle = BorderStyle.Fixed3D;
this.pictureBox1.Size = new Size(50, 50);
this.Size = new Size(450, 450);
this.DoubleBuffered = true;
this.Paint += Form1_Paint;
this.MouseMove += Form1_MouseMove;
}
To paint the circle I use a slightly modified version of your OnPaint handler:
private void Form1_Paint(object sender, PaintEventArgs e)
{
e.Graphics.Clear(Color.Black);
for (int i = 0; i < values.Count; i++)
{
Brush b = new SolidBrush(Color.FromArgb(255, Rescale(values[i]), 0, 0));
e.Graphics.FillPie(b, 0, 0, 400, 400, (float)i, 1.0f);
}
}
In the MouseMove event is where we do most of the heavy lifting:
private void Form1_MouseMove(object sender, MouseEventArgs e)
{
this.pictureBox1.Location = new Point(e.X + 5, e.Y - 5);
int segment = (int)GetAngle(new Rectangle(0, 0, 400, 400), e.Location);
this.pictureBox1.BackColor = Color.FromArgb(255, Rescale(segment), 0, 0);
}
You may notice that since there are 360 wedges are in increments of a degree, I just truncated the angle. If you need more precision, or you decide to use segments greater than 1 degree, then you could use various rounding algorithms to round the angle to the nearest section of the pie.
At last, we're ready to implement the GetAngle function. First we calculate the center of the circle, because everything is relative to that.
int cx = (rect.Width + rect.X) / 2;
int cy = (rect.Height + rect.Y) / 2;
Next calculate the difference between the mouse's position and the center of the rectangle. (I've inverted the y coordinate to line up with 'standard' Cartesian coordinates, to make things easier, and match the coordinates you'd see in a math textbook.)
float x = pTo.X - cx;
float y = (cy - pTo.Y);
Next check for the arctangent's undefined points (and a couple of shortcuts we can take):
if ((int)x == 0)
{
if (y > 0) return 270;
else return 90;
}
else if ((int)y == 0)
{
if (x > 0) return 0;
else return 180;
}
Calculate the internal angle:
float ccwAngle = (float)Math.Atan(Math.Abs(y) / Math.Abs(x));
And map that angle to the appropriate quadrant:
if (x > 0 && y > 0)
{
}
else if (x < 0 && y > 0)
{
ccwAngle = (float)Math.PI - ccwAngle;
}
else if (x < 0 && y < 0)
{
ccwAngle = ccwAngle + (float)Math.PI;
}
else if (x > 0 && y < 0)
{
ccwAngle *= -1f;
}
Convert the angle from degrees to radians and normalize (make sure it's between 0° and 360°)
ccwAngle *= (float)(180 / Math.PI);
while (ccwAngle > 360) ccwAngle -= 360;
while (ccwAngle < 0) ccwAngle += 360;
Finally convert the counter-clockwise angle we needed to do the math into the clockwise angle that GDI uses, and return the value:
return 360f - ccwAngle;
All that together produces the final result:
(The code above is also available as a complete example in this gist)

Move a rectangle using angles

I need to move a rectangle using angles. Actually I want to change the direction of my moving rectangle when it reaches the location I have given in my code in if statement!
I just need the way I can find out how to move my rectangle at 60, 30, 60, 120, 150, 270 degrees!
Suppose that if
circle.Y>=this.Height-80
See this:
I really actually need to change the direction of rectangle movement using angles! so that at certain location reaches I can change the rectangle direction according to angle of my own choice!
such that:
if(circle.Y>=this.Height-80)
move in the direction of 90 degrees
if(circle.X>=this.Width-80)
move in the direction of 60 degree
as you can see in the screen shot!
What I have been trying is:
public partial class Form1 : Form
{
Rectangle circle;
double dx = 2;
double dy = 2;
public Form1()
{
InitializeComponent();
circle = new Rectangle(10, 10, 40, 40);
}
private void Form1_Load(object sender, EventArgs e)
{
this.Refresh();
}
private void Form1_Paint(object sender, PaintEventArgs e)
{
Graphics g = e.Graphics;
g.SmoothingMode = SmoothingMode.AntiAlias;
g.FillEllipse(new SolidBrush(Color.Red), circle);
}
private void timer_Tick(object sender, EventArgs e)
{
circle.X += (int)dx;
circle.Y += (int)dy;
if (circle.Y>=this.Height-80)
{
dy = -Math.Acos(0) * dy/dy; //here i want to change the direction of circle at 90 degrees so that it should go up vertically straight with same speed
}
this.Refresh();
}
}
The Problem is that I have been trying changing my conditions to:
dy = -Math.Asin(1) * dy;
dx = Math.Acos(0) * dx ;
but in both cases nothing is happening and the direction remains same!
I just want to move the circle in inverted upward direction at 90 degrees when it reach at
circle.Y>=this.Height-80

You need to draw the rectangle again to some image for it to display. I created this code for moving and drawing rectangle on pictureBox1, using your already defined circle-rectangle:
Moving the rectangle:
public void MoveRectangle(ref Rectangle rectangle, double angle, double distance)
{
double angleRadians = (Math.PI * (angle) / 180.0);
rectangle.X = (int)((double)rectangle.X - (Math.Cos(angleRadians) * distance));
rectangle.Y = (int)((double)rectangle.Y - (Math.Sin(angleRadians) * distance));
}
Drawing the rectangle and displaying it in the PictureBox:
public void DrawRectangle(Rectangle rectangle)
{
Bitmap bmp = new Bitmap(pictureBox1.Width, pictureBox1.Height);
using (Graphics g = Graphics.FromImage(bmp))
{
g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;
g.FillEllipse(new SolidBrush(Color.Red), rectangle);
}
pictureBox1.Image = bmp;
}
Demo it with a button click:
private void Button1_Click(object sender, EventArgs e)
{
MoveRectangle(ref circle, 90, 5);
DrawRectangle(circle);
}

Math.Asin(1) * dy is a constant value. Thus, you should use, for example, an instance variable that increments in each Tick of your timer.
...And *dy/dy is irrelevant.
public partial class Form1 : Form
{
Rectangle circle;
double dx = 2;
double dy = 2;
acum=0; //the new variable
...
private void timer_Tick(object sender, EventArgs e)
{
circle.X += (int)dx;
circle.Y += (int)dy;
if (circle.Y>=this.Height-300)
{
dy = -Math.Acos(acum);
acum+=1; //your accumulator
}
this.Refresh();
}

acos and asin are the inverse of sin and cos so the output of those two functions is an angle (usually in radians). This makes the code incorrect.
I strongly suggest that you read up on vector and matrix maths as using Euler angles can get quite messy.
So, you will have a position vector P and a movement vector M and the current position is:
P' = P + M.t
where t is time, P is the original position and P' is the current position.
Then, when you want to change direction, you create a rotation matrix and multiply the movement vector M by this rotation matrix.
The advantage here is that you can step from a 2D system to a 3D system by adding a Z component to your vectors and increasing the size of your matrices.

Making a object bounce

I am trying to make a elipse bounce on a rectangle. I am using a timer to move the elipse in both x and y-direction. My idea was to create an if statement to see if the coordinates of the elipse matches the coordinates of the rectangle.
Here is the code I had written so far:
public partial class Form1 : Form
{
Class1 square = new Class1();
public int before;
public int after;
public int c;
public Form1()
{
InitializeComponent();
}
protected override void OnPaint(PaintEventArgs e)
{
after = 590 - (b * b) / 100;
before = 100 + (a * a) / 100;
c = a + b;
Graphics g = e.Graphics;
SolidBrush Brush = new SolidBrush(Color.White);
g.FillEllipse(Brush, a, before, 10, 10);
square.Draw(g);
if (k >= square.y && a >= square.x && a <= square.x + 40)
{
a=c;
before= after;
timer1.Start();
timer2.Stop();
}
else if (k >= square.y + 10)
{
timer2.Stop();
MessageBox.Show("You lost");
}
}
protected override void OnMouseMove(MouseEventArgs e)
{
base.OnMouseMove(e);
square.x = e.X;
Cursor.Hide();
}
public int a = 0;
public int b = 0;
public void timer2_Tick(object sender, EventArgs e)
{
a += 1;
Invalidate();
}
private void timer1_Tick(object sender, EventArgs e)
{
b += 1;
Invalidate();
}
}
I know that there are problems. And I have some questions:
Is there a easier way to make the elipse " bounce"?
Is the problem solely with the maths of the curve that the elipse is following?
I know the question may be somewhat undefined or abstract but any help is appriciated. And if you want me to be clearer in some ways, let me know! Thanks

A simple way to make the ellipse bounce of the edges is to check its edge points against the bounds, and then just invert the proper direction. So, something like this should work, if you'll pardon the pseudo-code
loop used to animate the ellipse
before moving, check the position:
if right-most position == right wall
invert x velocity
if left-most position == left wall
invert x velocity
if top-most position == top wall
invert y velocity
if bottom-most position == bottom wall
invert y velocity
move ellipse to next position
This is a pretty simple simulation, but it should give you an idea of how to progress and develop a more sophisticated model. Hope this helps!

How to scale the cube by pressing the button in C #?

I have a program that prints the cube and which can be rotated. Here's the code.
public partial class ProjectorForm : Form
{
Projector projector;
Cube cube;
float deltaRot;
public ProjectorForm()
{
InitializeComponent();
}
private void ProjectorForm_Load(object sender, EventArgs e)
{
deltaRot = 0.01f;
projector = new Projector();
cube = new Cube(Vector3.UnitZ * 20*10, 10*10, 10*10, 15*10);
updateTimer.Start();
}
private void updateTimer_Tick(object sender, EventArgs e)
{
if (rotXBox.Checked)
cube.RotateX(deltaRot);
if (rotYBox.Checked)
cube.RotateY(deltaRot);
if (rotZBox.Checked)
cube.RotateZ(deltaRot);
doubleBufferedPanel1.Invalidate();
}
private void doubleBufferedPanel1_Paint(object sender, PaintEventArgs e)
{
e.Graphics.Clear(Color.White);
cube.Draw(projector, Color.Black, doubleBufferedPanel1.ClientSize.Width, doubleBufferedPanel1.ClientSize.Height, e.Graphics);
}
private void button1_Click(object sender, EventArgs e)
{
deltaRot = float.Parse(deltaRotBox.Text);
}
}
class Projector
{
public Vector3 cameraPosition;
public float planeDistance;
ProjectorForm n = new ProjectorForm();
public Projector()
{
cameraPosition = Vector3.Zero;
planeDistance = 256; //Here, multiply by 2 and the scaled cube, how to make that scale when you press the button.
}
public PointF Project(Vector3 point, float width, float height)
{
float x = cameraPosition.X + ((cameraPosition.Z + planeDistance) / (point.Z - cameraPosition.Z)) * (point.X - cameraPosition.X) + width / 2;
float y = cameraPosition.Y + ((cameraPosition.Z + planeDistance) / (point.Z - cameraPosition.Z)) * (point.Y - cameraPosition.Y) + height / 2;
return new PointF(x, y);
}
public void DrawLine(Color color, Vector3 p1, Vector3 p2, float width, float height, Graphics g)
{
g.DrawLine(new Pen(color), Project(p1, width, height), Project(p2, width, height));
}
public void FillPolygon(Color color, Vector3[] vertices, float width, float height, Graphics g)
{
PointF[] points = new PointF[vertices.Length];
for (int i = 0; i < points.Length; i++)
points[i] = Project(vertices[i], width, height);
g.FillPolygon(new SolidBrush(color), points);
}
}
How to make a cube can be scaled by pressing a button. I found the variable planeDistance in the class Projector, when it increased by 2 times the cube is scaled, but I do not know how it can be increased by means of a button.

The field planeDistance is public, so you can change it from outside the class. i.e. just add something like the following to the event handler of a button:
projector.planeDistance += 10; // Change 10 as appropriate
It's worth noting that this doesn't change the size of the cube, it changes how far away the camera is from it. So, while the cube appears to be changing in size, that's just because the camera is moving closer / further away.
To actually change the size of the cube you would have to change fields in the cube class.
Since the size is defined by the vectors created in the constructor you don't really have an easy way of changing them once the cube is created.
You could create a new cube whenever you want to change the size (keep track of the size in another variable on the form).
You could add a method to the cube class that creates new vectors that define the new size (it would look a bit like the constructor, only populating the arrays, not creating them).
You could add a size field to your cube, always create a unit cube (1, 1, 1) then when rendering multiply each vector by your size.