Develop Reference

How to detect if user is shaking form c# (detect shake),

I've made a paint clone and want to clear the bord when you shake the form, (so by holding mouse1 down on the top bar and moving it right and left fast).
I tried to compare two points on the x-axis, the points are set based on the mouse position and tested against a treshold. And I added a combo so you need to overcome the treshold multiple times to avoid accidental activation, to help with this there is also a timer that resets the combo.
The problem is that it sees fast movement to one side as a shake I still want the user to be able to move the form without clearing the canvas.
int firstpos = 0;
int secondpos = 0;
bool isfirst = true;
int combo = 0;
int threshold = 50;
Point lastPoint;
private void TopBar_MouseMove(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left)//to move the form
{
this.Left += e.X - lastPoint.X;
this.Top += e.Y - lastPoint.Y;
}
if (isfirst)
{
firstpos = e.X;
isfirst = false;
}
else
{
secondpos = e.X;
int diff = secondpos - firstpos;
if (diff < 0) diff *= -1;//make positive
if (diff >= threshold)
{
combo++;
Thread t = new Thread(startdecay);
t.Start();
}
if (combo == 4)
{
canvas.Invalidate();//clear the canvas
combo = 0;
}
isfirst = true;
}
}
void startdecay()
{
Thread.Sleep(1000);
combo = 0;
}
private void TopBar_MouseDown(object sender, MouseEventArgs e)
{
lastPoint = new Point(e.X, e.Y);
}
the form

isfirst == true: Save firstpos.
Set isfirst = false.
isfirst == false: Get secondpos.
Get diff.
if Math.Sign(diff) != saveddiff {
increment shakecounter.
Set saveddiff = Math.Sign(diff).
}
Set firstpos = secondpos.
Accept when shakecounter over some value desired.
Don't forget to reset everything when Mouse Button goes up.

visual studio making characters move using classes and not picture boxes

im trying to make character move in VS without picture boxes, i seem to be getting close but when i tried to put in the key presses there is a red line under the key of key.keycodes and a red line under my public enum direction and i dont know why. here is my code, it isnt fully complete but you will probably get the idea. so what im asking in a nutshell is why cant i put in keycodes and why is my enum directional code underlined.
public enum Direction { Up, Right, Down, Left }
public class Cat
{
public Direction currentDirection = Direction.Up;
public PictureBox CatImage = new PictureBox();
public int mouseSize = 25;
public int maxScreenX;
public int maxScreenY;
private ImageList CatImages = new ImageList();
public Cat(Form formInstance)
{
maxScreenX = formInstance.Width - 50;
maxScreenY = formInstance.Height - 80;
// start with mouse in the centre of the screen
CatImage.Location = new System.Drawing.Point(maxScreenX / 2, maxScreenY / 2);
// we'll add the mouse images
CatImages.Images.Add(Properties.Resources.catUp);
CatImages.Images.Add(Properties.Resources.catRight);
CatImages.Images.Add(Properties.Resources.catDown);
CatImages.Images.Add(Properties.Resources.catLeft);
formInstance.Controls.Add(CatImage);
CatImage.BringToFront();
}
public void MoveMouse()
{
if (!canMove)
{
}
// Change the mouse image to match the new direction
CatImage.Image = CatImages.Images[(int)currentDirection];
if (canMove)
{
if (key.KeyCode == Keys.W)
{
CatImage.Top -= 5;
}
if (key.KeyCode == Keys.S)
{
CatImage.Top += 5;
}
if (key.KeyCode == Keys.A)
{
CatImage.Left -= 5;
}
if (key.KeyCode == Keys.D)
{
CatImage.Left += 5;
}
}
}
}

Setting the origin of a C# panel control, or moving its contained controls programmatically

So, I have a simple task (so I thought) - I have a panel control which contains a label control.
I have directional control buttons, and movement buttons. The movement buttons should move the location of the label control in either x or y direction depending on which movement button is selected. The selected direction is stored as a property of the Class.
All of these functions are working, except this: when I instantiate the Robot class, the pointer should be on the center of the screen. This needs to be the origin. However, by clicking the Move 10 button, the pointer moves to 0,10 (x,y) starting from the top left corner position.
Since I need the center to be the origin, I tried moving the control's 0,0 point to where I want it, but that makes any negative values (from the controls top left) invisible, which can not work.
I am hoping someone can explain to me how to fix this. Oh, while I am at it, why isnt the panel's border showing?
A Robot object is created from the class when the form loads. The directional and movement code is like this:
private void btnGoTen_Click(object sender, EventArgs e)
{
if (isValidDirection())
if (robot.Direction == "N")
robot.Y -= 10;
if (robot.Direction == "E")
robot.X -= 10;
if (robot.Direction == "S")
robot.Y += 10;
if (robot.Direction == "W")
robot.X += 10;
lblPosition.Text = robot.GetFormattedLocation();
lblRobotLoc.Location = new Point(robot.X, robot.Y);
}
private void btnNorth_Click(object sender, EventArgs e)
{
robot.Direction = "N";
}
private void btnEast_Click(object sender, EventArgs e)
{
robot.Direction = "E";
}
private void btnSouth_Click(object sender, EventArgs e)
{
robot.Direction = "S";
}
private void btnWest_Click(object sender, EventArgs e)
{
robot.Direction = "W";
}
And the class itself is simple enough, as follows:
public class Robot
{
//fields
private int x;
private int y;
private string direction;
public Robot()
{
x = 0;
y = 0;
direction = "N";
}
public int X
{
get { return x; }
set { x = value; }
}
public int Y
{
get { return y; }
set { y = value; }
}
public string Direction
{
get { return direction; }
set { direction = value; }
}
public string GetFormattedLocation()
{
string locationString = "{X=" + Convert.ToString(x) + ",Y=" + Convert.ToString(y) + "}";
return locationString;
}

Making breakout game

My friends I made some parts of this game but I have two problems in this game.
1)Problem about distinguishing ball collision with obstacles
1-1)A first problem is related to complex guidelines that I used them for simulation of ball collision with board or ball collision with blocks. These guidelines are not accurate especially when the ball meets with block corner or bottom.
If it is not better for collision distinguish I use a better code. I wrote this code. Are you think that are there better way?
2)How I can do a work that if the ball collision with any obstacle, the obstacle report the collision.
My aim is about using of events.
Are you thinking that I make obstacles as runtime?
If I make as a runtime, how I can make collision event for them?
With best regards
private Point MouseDownLocation;
int step = 2;
int stepleft = 2;
bool flagBottom;
bool flagTop;
private void Form1_Load(object sender, EventArgs e)
{
timer1.Interval = 10;
timer1.Enabled = true;
}
private void timer1_Tick(object sender, EventArgs e)
{
ball.Top += step;
ball.Left += stepleft;
//board simulate collision
bool collisonX = ball.Location.X + ball.Width > board.Location.X && ball.Location.X < board.Location.X + board.Width;
bool collisonY = ball.Top + ball.Height == board.Location.Y || ball.Top + ball.Height - 1 == board.Location.Y;
//board2(button1) simulate collision
bool collisonX2 = ball.Location.X + ball.Width > board2.Location.X && ball.Location.X < board2.Location.X + board2.Width;
bool collisonY2 = ball.Top + ball.Height == board2.Location.Y || ball.Top + ball.Height - 1 == board2.Location.Y;
//Collision the ball with under buttons
bool collsionButtonY = ball.Top - ball.Height == board2.Location.Y || ball.Top - ball.Height == board2.Location.Y - 1;
//collision leftwall
bool leftWall = ball.Left == 0 || ball.Left == -1 || ball.Left == 1;
//collision rightwall
bool topWall = ball.Top == 0 || ball.Top == -1 || ball.Top == 1;
bool bottomWall = collisonX && collisonY;
bool toppWall = collisonX2 && collisonY2;
//collision
bool barrier = collisonX2 && collsionButtonY;
//rightwall
bool rightWall = ball.Left + ball.Width == this.ClientSize.Width || ball.Left + ball.Width == this.ClientSize.Width - 1;
// sidewall = collision rightwall or leftwall
bool sideWall = leftWall || rightWall;
//Check the ball hit the ground
bool check = ball.Top + ball.Height < this.ClientSize.Height;
//if topWall true,This means that the ball is hit to the topwall
if (topWall)
{
flagBottom = false;
flagTop = true;
if (stepleft > 0)
{
step = 2;
}
else if (stepleft < 0)
{
step = 2;
}
}
//if bottomWall true,This means that the ball is hit to the board
else if (bottomWall)
{
flagBottom = true;
flagTop = false;
if (stepleft > 0)
{
step = step * -1;
}
else if (stepleft < 0)
{
step = step * -1;
}
}
//if barrier true and flagbottom true,This means that the ball is hit to the board2(button1)
else if (barrier && flagBottom)
{
if (stepleft > 0)
{
step = step * -1;
}
else if (stepleft < 0)
{
step = step * -1;
}
}
//if toppWall true and flagTop true,This means that the ball is hit to The top button is hit
else if (toppWall && flagTop)
{
if (stepleft > 0)
{
step = step * -1;
}
else if (stepleft < 0)
{
step = step * -1;
}
}
else if (sideWall)
{
//if leftwall true,This means that the ball is hit to the left side wall
if (leftWall)
{
if (flagTop)
{
stepleft = 2;
}
else if (flagBottom)
{
stepleft = 2;
}
}
//if rightWall true,This means that the ball is hit to the left side wall
else if (rightWall)
{
if (flagTop)
{
stepleft = -2;
}
else if (flagBottom)
{
stepleft = -2;
}
}
}
//check if ckeck==ture,this mean the ball is hit the ground
else if (!check)
{
timer1.Enabled = false;
}
}
private void board_MouseDown(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left)
{
MouseDownLocation = e.Location;
}
}
private void board_MouseMove(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left)
{
board.Left = e.X + board.Left - MouseDownLocation.X;
}
}

Define each "Wall" as an Object, this will increase your codes readablility. it will also allow you to define an Event for each wall, Listen to t. that way you know which wall has been hit
N.b. this is pseudo code. It wont compile :P
public class Wall
{
int X,Y,W,H;
//Define an event, add a listener to this, becuase we will fire this when there is a collision
public event EventHandler OnCollision;
public void CollisionCheck(Ball playerBall)
{
//1 Check for a collision with the "Ball" object
if(Ball.Rectangle().Intersects(this.Rectangle))
this.OnCollision(this, EventArgs.Empty); //Fire the event, null check might be requried
}
}

I do not know your game but (suspect 2D brick-like game)
Objects/Obstacles
all objects/obstacles can be simplified to rectangular objects
so make list of them with defined parameters like size and position
if they are movable/dropable then also speed and state...
type of object (affects color,scoring,capabilities...)
create member function like update(dt),draw()
create events you like OnHIt,OnCollision,...
for example (C++ pseudo code):
// game object types ...
enum _game_object_type_enum
{
_game_object_type_none=0,
_game_object_type_wall,
_game_object_type_brick1,
_game_object_type_brick2,
_game_object_type_brick3,
_game_object_type_bomb,
_game_object_type_joker1,
_game_object_type_joker2,
...
};
// game object class
class game_object
{
public;
int type; // type of object
float x,y,vx,vy,hx,hy; // position,speed,half size of rectangle
void update(float dt); // this call periodicaly in some timer updates positions,... and call events, dt is time passed
void draw(); // can add some rendering device context ...
};
// whole game class holds the game world/board/map and player(s) ...
class game_board
{
public;
game_object *go; int gos; // list of all objects in game
void update(float dt) { for (int i=0;i<gos;i++) go[i].update(dt); }
void draw() { for (int i=0;i<gos;i++) go[i].draw(); }
}
events and flow control
first define some events you need
either you use global function/pointers for that or as members
depends on your platform and to what you are used to
for example like this:
void OnCollisionFX(game_object o1,game_object o2)
{
// do something ...
}
void (*OnCollision)(game_object o1,game_object o2)=OnCollisionFX;
for player interactions only (like player controlled object collisions test only)
is better to handle this in game_object::update(dt) but you need to add player context
something like game_object::update(dt,plr)
where plr is pointer to player controlled object or player class
if you have massive interactivity between game objects (like brick/brick collisions)
then is better to handle this in game_board::update(dt)
because otherwise you will need to provide references for everything into update call
and that will quickly lead to heap/stack trashing and very slow performance
also more advanced multiple object collision/interaction approaches are better in main game class
here is an example for first case:
void game_object::update(float dt,game_object &plr)
{
// update position
x+=vx*dt;
y+=vy*dt;
// here you should make your own collision test of coarse
if (fabs(x-plr.x)<=hx+plr.hx)
if (fabs(y-plr.y)<=hy+plr.hy)
{
... do what you need like mirror or stop speed or clamp position ...
if (OnCollision) OnCollision(this,plr);
}
}
in second case you should check each object against each other
void game_board::update(float dt)
{
int i,j;
// update position
for (i=0;i<gos;i++)
{
go[i].x+=go[i].vx*dt;
go[i].y+=go[i].vy*dt;
}
// here you should make your own collision test of coarse
for (i=0;i<gos;i++)
for (j=i+1;j<gos;j++) // the lower indexes are already tested
if (fabs(go[i].x-go[j].x)<=go[i].hx+go[j].hx)
if (fabs(go[i].y-go[j].y)<=go[i].hy+go[j].hy)
{
... do what you need like mirror or stop speed or clamp position ...
if (OnCollision) OnCollision(go[i],go[j]);
}
}
performance
you can improve performance by use of type property
for example if some game objets are static then the do not need to update position
if some are indestructible then there can be also some processing avoided and so on ...
[notes]
dt/fps/speed should be combined
so in each frame your player controlled object or any moving object does not move further
then the half size of smallest object
if this is not true then you need better collision test
use line intersection algorithm
last position and actual position gives you one line
and object edge gives you the other one
if booth objects are moving then that is even more complicated :)

Drawing Line to next point in realtime

My current program allows the user to click a point, then click another point (at least 20 pixels away) and draws a line between the 2 points. I've used a Polyline so that this can be done multiple times. Though the set of all the lines only appear after all the click are done.
void DrawingCanvas_MouseUp(object sender, MouseButtonEventArgs e) {
Point position = e.GetPosition(this);
if (leftList == null) {
//starting a new set
leftList.Add(position);
lastPoint = position;
return;
}
//calculate distance, i.e. end click
double a = lastPoint.X - position.X;
double b = lastPoint.Y - position.Y;
double distance = Math.Sqrt(a * a + b * b);
if (distance > 20) {
//continue to add to list
leftList.Add(position);
lastPoint = position;
} else {
//end of the line
paint();
leftList = new PointCollection();
}
}
private void paint() {
Polyline line = new Polyline();
line.Visibility = System.Windows.Visibility.Visible;
line.StrokeThickness = 2;
line.Stroke = System.Windows.Media.Brushes.Black;
line.Points = leftList;
myCanvas.Children.Add(line);
}
So my question is two-fold:
A) How do I make it so that after each click the new line is immediately added.
B) How do I render a line between the last point and where the mouse cursor is currently at (i.e. just before you choose your next point)

The following simple example starts drawing a new polyline when the left mouse button is pressed and the mouse is moved by the minimum point distance of 20, with the button kept pressed. It draws the last polyline segment (to the current mouse position) in either red or green, depending on its length. If the mouse button is released and the length of the new segment is >= 20, a new point is appended to the polyline. Otherwise the polyline is terminated, and a new polyline can be created.
private Polyline polyline;
private Polyline segment = new Polyline { StrokeThickness = 2 };
private void Canvas_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
if (polyline == null)
{
var canvas = (Canvas)sender;
var point = e.GetPosition(canvas);
// create new polyline
polyline = new Polyline { Stroke = Brushes.Black, StrokeThickness = 2 };
polyline.Points.Add(point);
canvas.Children.Add(polyline);
// initialize current polyline segment
segment.Stroke = Brushes.Red;
segment.Points.Add(point);
segment.Points.Add(point);
canvas.Children.Add(segment);
}
}
private void Canvas_MouseMove(object sender, MouseEventArgs e)
{
if (polyline != null)
{
// update current polyline segment
var canvas = (Canvas)sender;
segment.Points[1] = e.GetPosition(canvas);
var distance = (segment.Points[0] - segment.Points[1]).Length;
segment.Stroke = distance >= 20 ? Brushes.Green : Brushes.Red;
}
}
private void Canvas_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
{
if (polyline != null)
{
var canvas = (Canvas)sender;
segment.Points[1] = e.GetPosition(canvas);
var distance = (segment.Points[0] - segment.Points[1]).Length;
if (distance >= 20)
{
polyline.Points.Add(segment.Points[1]);
segment.Points[0] = segment.Points[1];
}
else
{
if (polyline.Points.Count < 2)
{
canvas.Children.Remove(polyline);
}
polyline = null;
segment.Points.Clear();
canvas.Children.Remove(segment);
}
}
}

please maintain a collection of points on every click. in collection you can add one class which will have two properties like StartPoint and EndPoint.
when the mouse is clicked first time just add one class object to collection having start point only.
and when you click the mouse next time, ad end point to the last object of the class and meanwhile create a new object and assign this point as its start point and add it to collection, after that call the paint function.