Managed C++/CLI

25-Mar-11 14:20

I'm not sure how to go about this. What to use to draw the snake to the screen and how to get it to animate properly like grow in size when it collects an item or just moving around the screen. I was told not to use a Picture box but to use Panels and no timers.

http://www.youtube.com/watch?v=s2tlk1LpWjI&feature=related

Maybe start off more simple like in the vid the snake just grows and the entire snake body doesn't move.

Thanks in advance.

modified on Friday, March 25, 2011 8:38 PM

Richard Andrew x6425-Mar-11 14:40

25-Mar-11 14:40

Well, what's your best guess at how to accomplish this?

Most likely it has something to do with what's been taught most recently. What kinds of graphics features have been gone over?

The difficult we do right away...
...the impossible takes slightly longer.

Cyclone_S25-Mar-11 14:54

25-Mar-11 14:54

hmm my best guess would be to paint the snake onto the screen using some onpaint method which I don't know which one to use. And how to update it so it can be animated. I don't know much about Brushes or graphics in .net. But I did use owner drawn tool tips and menues.

I tried this and updated it using a timer and "this->Invalidate();" but it didn't do what I wanted.

virtual void OnPaint(PaintEventArgs^ e) override
{

}

Richard Andrew x6425-Mar-11 14:57

25-Mar-11 14:57

Personally, I would create segments of the snake out of small panel objects that have a solid foreground color.

Then, to move the snake, simply move the panel that's at the rear of the snake to the front of the snake.

The difficult we do right away...
...the impossible takes slightly longer.

Cyclone_S26-Mar-11 13:09

26-Mar-11 13:09

Hi,

So far I created a Snake_Part class. When the Form1 class is first created is calls the Make_Snake Function which creates 4 Snake_Part objects which are added to the list.

How do I move the last panel to the front. I'm using a list to store the Snake_Part instances. A timer will be used to move the snake. I need to some how find the last/first elements in the list and then move them acordingly.

#include "stdafx.h"
using namespace System;
using namespace System::Drawing;
using namespace System::Windows::Forms;
using namespace System::Collections::Generic; // Required to make lists.

public ref class Snake_Part
{
	public:
			Panel^ panel;

			Snake_Part( Form ^ form ) // Class Constructor.
			{ 
				panel = gcnew Panel();
				panel->BackColor = Color::Blue;
				panel->Width = 20; panel->Height = 20;
				form->Controls->Add(panel);
			}
};

public ref class Form1 : public Form 
{
	public:
			List<Snake_Part^>^ Parts; // A list that contains the snake parts.
			int length; // The length of the  snake.
			Timer^ Timer1; // The timer that will move the snake;
			//Panel^ p;
			Form1() // Class constructor.
			{	
				Parts = gcnew List<Snake_Part^>();
				Timer1 = gcnew Timer();
				Timer1->Interval = 2000;
				Timer1->Start();
				Timer1->Tick += gcnew System::EventHandler(this, &Form1::timer1_Tick);
				Make_Snake();
			}
			
			void Make_Snake()
			{
				double clr = 255;
				double dclr = 128 / 2;

				for(int I = 0; I <= 3; I++)
				{
					Snake_Part^ p = gcnew Snake_Part(this);
					p->panel->BackColor = Color::FromArgb(0,0,clr);
					Parts->Add(p);
					clr -= dclr;
				}

				for each (Snake_Part^ p in Parts)
				{
					length += p->panel->Width + 2;
					p->panel->Left = length;
				}	
			}

			void move_snake()
			{
					
			}

			System::Void timer1_Tick(System::Object^  sender, System::EventArgs^  e) // A timer that will move the snake;
			{
				move_snake();
				
			}
};

[STAThread]
int main()
{
    Application::Run(gcnew Form1());
}

Thanks

Richard Andrew x6426-Mar-11 13:50

26-Mar-11 13:50

A couple of suggestions. You might want to use a Queue to store the snake segments. That makes it easy to retrieve the last segment and push it onto the front. But a List will work too.

You'll need a value that determines what direction the snake is moving in. Maybe two values, an X and Y value. These should be integers so that they can store 1, 0, or -1.

From there, you can calculate where to position the panel, based upon the head segment's X and Y values, multiplied by the movement indicator values.

The flow would be as follows:

Retrieve the last segment.

Store it in the Head segment holder variable.

Push it onto the front of the snake.

Calculate the new head position.

Position the Head segment according to the new position.

The difficult we do right away...
...the impossible takes slightly longer.

Cyclone_S27-Mar-11 13:27

27-Mar-11 13:27

Thanks for the helpful suggestions. I got it to move the snake right fine but I need help with some of the coding to get it to move properly in the other directions. I'm curently trying to move the snake downwards but I'm stuck. Thanks.

#include "stdafx.h"
using namespace System;
using namespace System::Drawing;
using namespace System::Windows::Forms;
using namespace System::Collections::Generic; // Required to make lists.

public ref class snake_segment
{
	public:
			Panel^ panel;

			snake_segment( Form ^ form ) // Class Constructor.
			{ 
				panel = gcnew Panel();
				panel->BackColor = Color::Blue;
				panel->Width = 20; panel->Height = 20;
				form->Controls->Add(panel);
			}
};

public ref class Form1 : public Form 
{
	public:
			List<snake_segment^>^ segments; // A list that contains the snake segments.
			int l; // Length of the snake at begining of game.
			int size; // The number of segments in snake/list.
			int last;  // The last segment of in the snake.
			int x, y; // The coordinates of the snake segment(head).
			int x2,y2; // Values that will store the direction the snake will move.
			Timer^ Timer1; // The timer that will move the snake;
			bool game_started;

			Form1() // Class constructor.
			{	
				segments = gcnew List<snake_segment^>();
				Timer1 = gcnew Timer();
				Timer1->Interval = 2000;
				Timer1->Start();
				Timer1->Tick += gcnew System::EventHandler(this, &Form1::timer1_Tick);
				this->KeyDown += gcnew System::Windows::Forms::KeyEventHandler(this, &Form1::Form_KeyDown);
				Make_Snake();
			}
			
			void Make_Snake()
			{
				double clr = 255;
				double dclr = 128 / 2;

				for(int I = 0; I <= 3; I++)
				{
					snake_segment^ s = gcnew snake_segment(this);
					s->panel->BackColor = Color::FromArgb(0,0,clr);
					segments->Add(s);
					clr -= dclr;
				}

				for each (snake_segment^ s in segments)
				{
					l += s->panel->Width + 2;
					s->panel->Left = l;
				}	
			}

			void get_size_of_snake()
			{
				size=0;
				for each (snake_segment^ s in segments)
				{
					size++;	
				}				
			}

			void head_position() // The head position at start of game.
			{
				x = segments[size-1]->panel->Left;
				y = segments[size-1]->panel->Top;
			}

			void move_snake()
			{
				if(x2 ==1){segments[last]->panel->Left = x + segments[last]->panel->Width + 2;} // Move snake right.
				if(y2 == -1){segments[last]->panel->Left = x;segments[last]->panel->Top = x;} // Move snake down.
				x = segments[last]->panel->Left;
				y = segments[last]->panel->Top;
				last++;
				if(last >= size){last=0;}
			}

			System::Void timer1_Tick(System::Object^  sender, System::EventArgs^  e) // A timer that will move the snake;
			{
				get_size_of_snake();
				if(!game_started){head_position();game_started=true;} // Find first head position at start of game.
				move_snake();
			}

			System::Void Form_KeyDown(System::Object^ sender, System::Windows::Forms::KeyEventArgs^ e)
			{
				if(e->KeyCode == Keys::Down){y2 = -1;}
				if(e->KeyCode == Keys::Up){y2 = 1;}
				if(e->KeyCode == Keys::Left){x2 = -1;}
				if(e->KeyCode == Keys::Right){x2 = 1;}
			}
};

[STAThread]
int main()
{
    Application::Run(gcnew Form1());
}

Richard Andrew x6427-Mar-11 14:12

27-Mar-11 14:12

I think you have the values for y2 reversed in the Key handler.

If you want the snake to move down, you should be incrementing y2, and decrementing it for up.

The difficult we do right away...
...the impossible takes slightly longer.

Cyclone_S27-Mar-11 14:25

27-Mar-11 14:25

The snake automaticaly moves once the right key is pressed. It sorta works but not sure on how to code it for it moving downwords.

Here is the move_snake function;

void move_snake()
			{
				if(x2 ==1) // Move snake right.
				{
					segments[last]->panel->Left = x + segments[last]->panel->Width + 2;
					x = segments[last]->panel->Left;
					y = segments[last]->panel->Top;
					last++;
					if(last >= size){last=0;}
				} 
				if(y2 == -1) // Move snake down.
				{
					segments[last]->panel->Top = y + segments[last]->panel->Height + 2;
					segments[last]->panel->Left = x;
					x = segments[last]->panel->Left;
					y = segments[last]->panel->Top;
					last++;
					if(last >= size){last=0;}
				} 
				
			}

Would you be able to help with the code. It would be much aprecieated. Thanks.

Richard Andrew x6427-Mar-11 15:24

27-Mar-11 15:24

I think the problem might be that you're not keeping track of which panel is at the head of the snake, since movement is referenced against the head panel.

The code might go something like this: ( I have not tested this code. It might need modification. )

if ( y2 == -1 ) // Move down
{
    segments[last]->panel->Top = y + segments[head]->panel->Top + 2;
    segments[last]->panel->Left = segments[head]->panel->Left;

    head = last;
    last++;
    if ( last >= size )
    {
        last = 0;
    }

}

The difficult we do right away...
...the impossible takes slightly longer.

Cyclone_S28-Mar-11 13:21

28-Mar-11 13:21

You are correct, that's what the problem was. The snake is now moving in all directions. Thanks for helping me out. Smile | :)

Cyclone_S30-Mar-11 13:22

30-Mar-11 13:22

One last thing. I got the collision function working 99% but there's a small glitch where if
the head collides with the tail the collision function doesn't catch it and the snake keeps moving.

The collision function.

void check_for_collision()
			{
				for(int Tail = 0; Tail <= (size-1); Tail++)
				{
					for(int I = 0;I <= (size-1); I++)
					{
						if(I != head){segments[I]->panel->BackColor= Color::Blue;} else
						{
							segments[head]->panel->BackColor= Color::Yellow; // Color the head a different yellow.
						}

						if(head!= Tail && segments[head]->panel->Left == segments[Tail]->panel->Left && segments[head]->panel->Top == segments[Tail]->panel->Top) // Detect a collision is segments overlap.
						{
							segments[head]->panel->BackColor= Color::Red;
							Timer1->Stop();
						}
					
					}
				}
			}

Entire code.

#include "stdafx.h"
using namespace System;
using namespace System::Drawing;
using namespace System::Windows::Forms;
using namespace System::Collections::Generic; // Required to make lists.

public ref class snake_segment
{
	public:
			Panel^ panel; // A Panel is used to make the snake.

			snake_segment( Form ^ form ) // Class Constructor.
			{ 
				
				panel = gcnew Panel();
				//panel->BackColor= Color::Blue;
				panel->Width = 20; panel->Height = 20;
				form->Controls->Add(panel);
			}
};

public ref class Form1 : public Form 
{
	public:
			List<snake_segment^>^ segments; // A list that contains the snake segments.
			int l; // Length of the snake at begining of game.
			int size; // The number of segments in snake/list.
			int tail;  // The tail segment of the snake.
			int head;  // The head segment of the snake.
			int x, y; // The coordinates of the snake segment(head).
			int direction; // Stores the direction the snake will move.
			Timer^ Timer1; // The timer that will move the snake.
			bool game_started;
			

			Form1() // Class constructor.
			{	
				segments = gcnew List<snake_segment^>();
				Timer1 = gcnew Timer();
				Timer1->Interval = 500;
				Timer1->Start();
				Timer1->Tick += gcnew System::EventHandler(this, &Form1::timer1_Tick);
				this->KeyDown += gcnew System::Windows::Forms::KeyEventHandler(this, &Form1::Form_KeyDown);
				Make_Snake();
			}
			
			void Make_Snake()
			{
				for(int I = 0; I <= 5; I++)
				{
					snake_segment^ s = gcnew snake_segment(this);
					s->panel->BackColor = Color::FromArgb(0,0,255);
					segments->Add(s);
				}

				for each (snake_segment^ s in segments) // Position the segments at start of game.
				{
					l += s->panel->Width + 2;
					s->panel->Left = l;
				}
				get_size_of_snake();
				segments[size-1]->panel->BackColor= Color::Yellow; // Color the head yellow.
			}

			void get_size_of_snake() // Get the size of the snake when a new segment is added by eating something etc.
			{
				size=0;
				for each (snake_segment^ s in segments)
				{
					size++;	
				}
				head=size-1;
			}

			void head_position() // The head position at start of game.
			{
				x = segments[size-1]->panel->Left;
				y = segments[size-1]->panel->Top;
			}

			void move_snake()
			{
				if(direction==1) // Move snake left.
				{
					segments[tail]->panel->Location = Drawing::Point(x - 20 - 2,y); // Note using "Location" instead of "Left/Top" solved a problem where the segment would flicker as it's being moved to the head position.
					head = tail;
					x = segments[head]->panel->Left;
					y = segments[head]->panel->Top;
					tail++;
					if(tail >= size){tail=0;}
				}

				if(direction==-1) // Move snake right.
				{
					segments[tail]->panel->Location = Drawing::Point(x + 20 + 2,y);
					head = tail;
					x = segments[head]->panel->Left;
					y = segments[head]->panel->Top;
					tail++;
					if(tail >= size){tail=0;}
				}

				if(direction==2) // Move snake up;
				{
					segments[tail]->panel->Location = Drawing::Point(x,y - 20 - 2);
					head = tail;
					x = segments[head]->panel->Left;
					y = segments[head]->panel->Top;
					tail++;
					if(tail >= size){tail=0;}
				}
				
				if(direction==-2) // Move snake down;
				{
					segments[tail]->panel->Location = Drawing::Point(x,y + 20 + 2);
					head = tail;
					x = segments[head]->panel->Left;
					y = segments[head]->panel->Top;
					tail++;
					if(tail >= size){tail=0;}
				}
				
			}

			void check_for_collision()
			{
				for(int Tail = 0; Tail <= (size-1); Tail++)
				{
					for(int I = 0;I <= (size-1); I++)
					{
						if(I != head){segments[I]->panel->BackColor= Color::Blue;} else
						{
							segments[head]->panel->BackColor= Color::Yellow; // Color the head a different yellow.
						}

						if(head!= Tail && segments[head]->panel->Left == segments[Tail]->panel->Left && segments[head]->panel->Top == segments[Tail]->panel->Top) // Detect a collision is segments overlap.
						{
							segments[head]->panel->BackColor= Color::Red;
							Timer1->Stop();
						}
					
					}
				}
			}

			System::Void timer1_Tick(System::Object^  sender, System::EventArgs^  e) // A timer that will move the snake;
			{
				
				if(!game_started){head_position();game_started=true;} // Find first head position at start of game.
				move_snake();
				check_for_collision();
			}

			System::Void Form_KeyDown(System::Object^ sender, System::Windows::Forms::KeyEventArgs^ e)
			{
				if(e->KeyCode == Keys::Left){direction=1;}
				if(e->KeyCode == Keys::Right){direction=-1;}
				if(e->KeyCode == Keys::Up){direction=2;}
				if(e->KeyCode == Keys::Down){direction=-2;}

				if(e->KeyCode == Keys::Space) // Add a new segment to the snake.
				{
					snake_segment^ s = gcnew snake_segment(this);
					segments->Insert(tail,s);
					head = tail;
					segments[tail]->panel->Location = Drawing::Point(x + segments[head]->panel->Width + 2,y); 
					x = segments[head]->panel->Left;
					y = segments[head]->panel->Top;
					tail++;
					get_size_of_snake();
					if(tail >= size){tail=0;}
				}	
			}
};

[STAThread]
int main()
{
    Application::Run(gcnew Form1());
}

Thanks.

Richard Andrew x6430-Mar-11 14:41

30-Mar-11 14:41

I think you should simplify the collision function. I don't think you need two loops.

If you want to check whether the head is colliding with any of the other segments, then just do:

for (int ThisSegment = 0; ThisSegment < (size-1); ThisSegment ++ )
{
    if ( ThisSegment == head ) continue;

    if ( segments[ThisSegment]->panel->Left == segments[head]->panel->Left &&
         segments[ThisSegment]->panel->Top  == segments[head]->panel->Top )
    {
        Timer->Stop();
    }
}

The difficult we do right away...
...the impossible takes slightly longer.

Cyclone_S31-Mar-11 9:14

31-Mar-11 9:14

Thanks. Thats much simpler code then what I had.

Cyclone_S16-Apr-11 8:44

issue while loading MFC extension dll dynamically

16-Apr-11 8:44

Hi Richard. I was wondering if you would be able to help me with a bit of code. I posted it here. Thank You.

[Algorthm][^]

ptr_Electron24-Mar-11 23:37

ptr_Electron

24-Mar-11 23:37

I had MFC dll which exposes some clases. I would like to load this dll dynamically.

hResult = LoadLibrary(_T("c:\test.dll));
if (0 != hResult)
{
		_InitSomeDLLFun = (InitSomeDLL)::GetProcAddress(hResult, "InitSomeDLL");
// always Undefind value is returned by GetProcAddress
																		  
		if(_InitSomeDLL)
		{
			_InitSomeDLLFun();
		}
		err = GetLastError();

}

Please advice

Re: issue while loading MFC extension dll dynamically

Richard MacCutchan25-Mar-11 0:02

Richard MacCutchan

25-Mar-11 0:02

What error is returned? Have you checked that InitSomeDLL is exported by your DLL and is not a mangled C++ name?

I must get a clever new signature for 2011.

Re: issue while loading MFC extension dll dynamically

ptr_Electron25-Mar-11 0:21

ptr_Electron

25-Mar-11 0:21

The LoadLibrary() call was sucessfull, but
GetProcAddress() always returns <undefind value="">

the dlls are unmanaged dlls.

Please advice

Re: issue while loading MFC extension dll dynamically

Richard MacCutchan25-Mar-11 1:03

Richard MacCutchan

25-Mar-11 1:03

Very interesting, but you didn't answer my questions.

I must get a clever new signature for 2011.

Re: issue while loading MFC extension dll dynamically

ptr_Electron25-Mar-11 2:50

ptr_Electron

25-Mar-11 2:50

GetLastError() after the GetProcAddress returnts error code: 127

Re: issue while loading MFC extension dll dynamically

Richard MacCutchan25-Mar-11 4:24

Richard MacCutchan

25-Mar-11 4:24

Did you bother to look up error code 127 to see what it indicates? I guess not; see here[^] for more information. Now you know what's wrong you can probably make a start at fixing it.

I must get a clever new signature for 2011.

Instances of an object

Cyclone_S19-Mar-11 15:47