Develop Reference

Check collision and prevent overlap

I can't seem to figure out how to make this simple animation work, where i have user control over a red square, and it shouldn't overlap/intersect with a black square (e.g. a wall sprite)
My best effort is to have stack data structure of keys pressed and if there is an intersection, then we look at (peek) last key pressed and assign a speed of -1. (See line 67 of code) But this doesn't prevent an overlap. Is there a way that I can make it so the user's red rectangle can't overlap with black?
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Collections;
namespace Movement
{
public partial class Form1 : Form
{
bool moveRight, moveLeft, moveUp, moveDown;
Keys currentInput;
Keys lastInput;
Stack pressedKeys = new Stack();
int speed = 5;
bool collision = false;
public Form1()
{
InitializeComponent();
this.CenterToScreen();
}
private void pbRed_Click(object sender, EventArgs e)
{
}
private void moveTimeEvent(object sender, EventArgs e)
{
currentInput = Keys.KeyCode;
//moving left
if (moveLeft == true && pbRed.Left > 7 )
{
pbRed.Left -= speed;
}
//moving right
if (moveRight == true && pbRed.Left < 750)
{
pbRed.Left += speed;
}
//moving up
if(moveUp == true && pbRed.Top > 7)
{
pbRed.Top -= speed;
}
//moving down
if(moveDown == true && pbRed.Top < 400)
{
pbRed.Top += speed;
}
if (moveLeft == true || moveRight == true || moveUp == true || moveDown == true)
{
pressedKeys.Push(currentInput);
}
Collision();
}
private void Collision()
{
//collision detection
if(pbRed.Bounds.IntersectsWith(pbBlack.Bounds))
{
collision = true;
if(collision)
{
lastInput = (Keys)pressedKeys.Peek();
if(currentInput == lastInput)
{
speed = -1;
}
}
}
}
private void keyisdown(object sender, KeyEventArgs e)
{
if(e.KeyCode == Keys.Left)
{
moveLeft = true;
}
if (e.KeyCode == Keys.Right)
{
moveRight = true;
}
if (e.KeyCode == Keys.Up)
{
moveUp = true;
}
if (e.KeyCode == Keys.Down)
{
moveDown = true;
}
}
private void keyisup(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.Left)
{
moveLeft = false;
}
if (e.KeyCode == Keys.Right)
{
moveRight = false;
}
if (e.KeyCode == Keys.Up)
{
moveUp = false;
}
if (e.KeyCode == Keys.Down)
{
moveDown = false;
}
}
}
}

When your speed is 5, don't apply a movement of 5 pixels in one go, but apply the 5 steps separately. Before each step, so before actually moving the rectangle, decide whether that one step movement is allowed.
Also look at vertical and horizontal movement separately.
using System;
using System.Drawing;
using System.Windows.Forms;
namespace Movement
{
public partial class Form1 : Form
{
bool moveRight, moveLeft, moveUp, moveDown;
int speed = 5;
public Form1()
{
InitializeComponent();
this.CenterToScreen();
}
private void moveTimeEvent(object sender, EventArgs e)
{
// Get movement vector
Point movement = new Point(0, 0);
if (moveLeft) movement.X -= 1;
if (moveRight) movement.X += 1;
if (moveUp) movement.Y -= 1;
if (moveDown) movement.Y += 1;
// Speed defines how many steps we move
for (int i=1; i<= speed; i++)
{
// Check vertical movement allowed
if (movement.X != 0)
{
Rectangle newPosition = pbRed.Bounds;
newPosition.X += movement.X;
if (!CheckCollision(newPosition))
{
movement.X = 0;
}
}
// Check horizontal movement allowed
if (movement.Y != 0)
{
Rectangle newPosition = pbRed.Bounds;
newPosition.X += movement.X;
newPosition.Y += movement.Y;
if (!CheckCollision(newPosition))
{
movement.Y = 0;
}
}
// Apply Actual movement
if (!movement.IsEmpty)
{
Rectangle newPosition = pbRed.Bounds;
newPosition.X += movement.X;
newPosition.Y += movement.Y;
pbRed.Bounds = newPosition;
}
}
}
// Returns true when movingRecht is allowed position
private bool CheckCollision(Rectangle movingRect)
{
bool lResult = true;
//collision detection
lResult = lResult && !pbBlack.Bounds.IntersectsWith(movingRect);
// Check we remain inside the form
lResult = lResult && movingRect.Left >= 0;
lResult = lResult && movingRect.Top >= 0;
lResult = lResult && movingRect.Right <= ClientRectangle.Right;
lResult = lResult && movingRect.Bottom <= ClientRectangle.Bottom;
return lResult;
}
private void keyisdown(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.Left)
{
moveLeft = true;
}
if (e.KeyCode == Keys.Right)
{
moveRight = true;
}
if (e.KeyCode == Keys.Up)
{
moveUp = true;
}
if (e.KeyCode == Keys.Down)
{
moveDown = true;
}
}
private void keyisup(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.Left)
{
moveLeft = false;
}
if (e.KeyCode == Keys.Right)
{
moveRight = false;
}
if (e.KeyCode == Keys.Up)
{
moveUp = false;
}
if (e.KeyCode == Keys.Down)
{
moveDown = false;
}
}
}
}

How do I move an object using a timer and the key press event (Like snake)

I want to move a button automatically using a timer and want it to change direction when another key is pressed, kinda like what happens in snake
I have used a string to set what the direction should be, but this doesn't work.
string x = "right";
public Form1()
{
InitializeComponent();
timer1.Interval = 1000;
timer1.Start();
}
private void Player_KeyDown(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.W)
{
string x = "up";
}
else if (e.KeyCode == Keys.S)
{
string x = "down";
}
else if (e.KeyCode == Keys.D)
{
string x = "right";
}
else if (e.KeyCode == Keys.A)
{
string x = "left";
}
}
private void Form1_Load(object sender, EventArgs e)
{
}
private void Timer1_Tick(object sender, EventArgs e)
{
while (x == "up")
{
Player.Top -= 10;
}
while (x == "down")
{
Player.Top += 10;
}
while (x == "right")
{
Player.Left += 10;
}
while (x == "left")
{
Player.Left -= 10;
}
}
}
The button just disappears, but I want it to move by ten until it gets a key press like "D" then it changes direction

1: You are creating variable 'x' every time means locally in player_keyDown event so create it globally.
2: you are using while loop it, not needed as you are already using timer_tick.
3: Instead of Top, Left use Location property of button it gives you X, Y co-ordinate
public partial class Form2 : Form
{
public Form2()
{
InitializeComponent();
timer1.Interval = 1000;
timer1.Start();
}
string x = "right";
private void Player_KeyDown(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.W)
{
x = "up";
}
else if (e.KeyCode == Keys.S)
{
x = "down";
}
else if (e.KeyCode == Keys.D)
{
x = "right";
}
else if (e.KeyCode == Keys.A)
{
x = "left";
}
}
private void timer1_Tick(object sender, EventArgs e)
{
if (x == "up")
{
Player.Location = new System.Drawing.Point(Player.Location.X, Player.Location.Y - 10);
}
if (x == "down")
{
Player.Location = new System.Drawing.Point(Player.Location.X, Player.Location.Y + 10);
}
if (x == "right")
{
Player.Location = new System.Drawing.Point(Player.Location.X + 10, Player.Location.Y);
}
if (x == "left")
{
Player.Location = new System.Drawing.Point(Player.Location.X - 10, Player.Location.Y);
}
}
}

2-player KeyDown has undesirable behavior

I have Player1Y and Player2Y for two players' Y value.
I want Player1 to decrease its Y value when pressing W to move it up. Same goes for Player2 but by pressing Up.
I'm using this code:
private void Form1_KeyDown(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.Up && Player2Y > 0)
{
Player2Y -= 5;
Invalidate();
}
if (e.KeyCode == Keys.W && Player1Y > 0)
{
Player1Y -= 5;
Invalidate();
}
}
The problem is that there are 2 players and when they press W and Up at the same time, only one player moves depending on who pressed last. How can I solve this problem?

I think you should add a synchronization lock to your code:
private System.Object _synchLock = new System.Object();
private void Form1_KeyDown(object sender, KeyEventArgs e)
{
lock(_synchLock)
{
if (e.KeyCode == Keys.Up && Player2Y > 0)
{
Player2Y -= 5;
Invalidate();
}
if (e.KeyCode == Keys.W && Player1Y > 0)
{
Player1Y -= 5;
Invalidate();
}
}
}

Add additional flag for check a change Y by any player. I think if keys Up and W is pressed in one event's handler then believe that it is pressed simultaneously. So main that you move only one player in handler event.
private void Form1_KeyDown(object sender, KeyEventArgs e)
{
bool isYChanged = false;
if (e.KeyCode == Keys.Up && Player2Y > 0)
{
Player2Y -= 5;
Invalidate();
isYChanged = true;
}
if (e.KeyCode == Keys.W && Player1Y > 0 && isYChanged == false)
{
Player1Y -= 5;
Invalidate();
}
}

How to prevent two events about the same thing happening

Basically,I am a beginner in C# and I just started working on a simple platformer game following a basic Visual Studio 2015 tutorial.This is the code:
public partial class Form1 : Form
{
bool goleft = false;
bool goright = false;
bool jumping = false;
int JumpSpeed = 10;
int force = 8;
int score = 0;
public Form1()
{
InitializeComponent();
}
private void keyisdown(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.Left)
{
goleft = true;
}
if (e.KeyCode == Keys.Right)
{
goright = true;
}
if (e.KeyCode == Keys.Space && !jumping)
{
jumping = true;
}
}
private void keyisup(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.Left)
{
goleft = false;
}
if (e.KeyCode == Keys.Right)
{
goright = false;
}
if (jumping)
{
jumping = false;
}
}
private void timer1_Tick(object sender, EventArgs e)
{
player.Top += JumpSpeed;
if (jumping && force < 0)
{
jumping = false;
}
if (goleft)
{
player.Left -= 5;
}
if (goright)
{
player.Left += 5;
}
if (jumping)
{
JumpSpeed = -12;
force -= 1;
}
else
{
JumpSpeed = 12;
}
foreach (Control x in this.Controls)
{
if (x is PictureBox && x.Tag == "p")
{
if (player.Bounds.IntersectsWith(x.Bounds) && !jumping)
{
force = 8;
player.Top = x.Top - player.Height;
}
}
if (player.Bounds.IntersectsWith(Door.Bounds))
{
timer1.Stop();
MessageBox.Show("You Won!");
this.Close();
}
}
}
}
The gravity force and everything works great EXCEPT for one big problem with the player that I definitely can't solve without some help.
The problem is: the player is completely glitched and it keeps going up and down. I realised that this is because of two lines in private void timer1_Tick(object sender, EventArgs e):
player.Top += JumpSpeed;
and
player.Top = x.Top - player.Height;
Both of these try to change player.Top and interfere with each other. The trouble is that I can't just cut one of the two without destroying the gravity force code. What I think might work is applying player.Top += JumpSpeed; ONLY if(player.Bounds.IntersectsWith(x.Bounds) && !jumping) = false but I don't know how to write the code this way at all (previous tries always ended up with errors).
Thanks in advance for any help and please forgive any grammar errors that I made because I am not a native english speaker.

I don't know how your Form looks like, but with what you provided I would change the code like that:
public partial class Form1 : Form
{
bool goleft = false;
bool goright = false;
int JumpSpeed = 0; //current vertical speed
int force = 8; //initial jump speed
int score = 0;
public Form1()
{
InitializeComponent();
}
private void keyisdown(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.Left)
{
goleft = true;
}
if (e.KeyCode == Keys.Right)
{
goright = true;
}
if (e.KeyCode == Keys.Space && JumpSpeed==0) //JumpSpeed==0 to prevent "double jump"
{
JumpSpeed = force; //start jumping with full power
}
}
private void keyisup(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.Left)
{
goleft = false;
}
if (e.KeyCode == Keys.Right)
{
goright = false;
}
}
private void timer1_Tick(object sender, EventArgs e)
{
if (goleft)
{
player.Left -= 5;
}
if (goright)
{
player.Left += 5;
}
JumpSpeed -= 1; //decrement the vertical speed = gravity -> choose higher value to bring him back on the ground quicker
player.Top -= JumpSpeed;
if (player.Bounds.IntersectsWith(Door.Bounds))
{
timer1.Stop();
MessageBox.Show("You Won!");
this.Close();
}
foreach (PictureBox x in this.Controls.OfType<PictureBox>())
{
if (x.Tag == "p")
{
if (player.Bounds.IntersectsWith(x.Bounds)) //if the player should be able to jump/walk on something the code is
{
player.Top = x.Top - player.Height;
JumpSpeed = 0; //the player stops falling
}
}
}
}
}
To make sure to player does not fall out of the window place PictureBoxes with tag == p on the floor!
PS:
Feel free to leave a comment!

c# need help by moving a object in two direction

I need help by moving a object on a Panel in two different direction. In example in the right and down direction by pressing the right and left buttons. Java have a a key release method do c# have such a similiar method?
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace runningRectangle
{
enum Position {Left, Right, Down, Up, LeftUp, LeftDown, RightUp, RightDown }
public partial class Form1 : Form
{
private int x;
private int y;
private Position objPos;
private int speed = 10;
private bool stopPressed = false;
public Form1()
{
InitializeComponent();
x = 50;
y = 50;
}
private void Form1_Paint(object sender, PaintEventArgs e)
{
e.Graphics.FillRectangle(Brushes.Red, x, y, 50, 50);
}
private void timer1_Tick(object sender, EventArgs e)
{
if(objPos == Position.Right)
{
x += speed;
}else if(objPos == Position.Left)
{
x -= speed;
}
else if (objPos == Position.Down)
{
y += speed;
}
else if (objPos == Position.Up)
{
y -= speed;
} else if (objPos == Position.RightUp)
{
x += speed;
y -= speed;
}
else if (objPos == Position.RightDown)
{
x += speed;
y += speed;
}
else if (objPos == Position.LeftUp)
{
x -= speed;
y += speed;
}
else if (objPos == Position.LeftDown)
{
x -= speed;
y -= speed;
}
Invalidate();
}
private void Form1_KeyDown(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.Right)
{
objPos = Position.Right;
}
else if (e.KeyCode == Keys.Left)
{
objPos = Position.Left;
}
else if (e.KeyCode == Keys.Down)
{
objPos = Position.Down;
}
else if (e.KeyCode == Keys.Up)
{
objPos = Position.Up;
}
else if(e.KeyCode == Keys.Right && e.KeyCode == Keys.Down)
{
objPos = Position.RightDown;
}
else if (e.KeyCode == Keys.Right && e.KeyCode == Keys.Up)
{
objPos = Position.RightUp;
}
else if (e.KeyCode == Keys.Left && e.KeyCode == Keys.Down)
{
objPos = Position.LeftDown;
}
else if (e.KeyCode == Keys.Left && e.KeyCode == Keys.Up)
{
objPos = Position.LeftUp;
}
else if(e.KeyCode == Keys.Space)
{
if (!stopPressed)
{
speed = 0;
stopPressed = true;
}
else if(stopPressed)
{
speed += 10;
stopPressed = false;
}
}
}
}
}

Form1_KeyDown and Form1_KeyUp exist in pair.
enum Position { None = -1, Left, Right, Down, Up, LeftUp, LeftDown, RightUp, RightDown }
private void Form1_KeyUp(object sender, KeyEventArgs e)
{
objPos = (Position)(-1);
}