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OpenGL Getting the cursor position

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apocalypse_k40    122
Hello everyone, I am using CsGL/C# for developing a simple checkers game. I follow the tutorials and lessons of Jerome JOUVIE (, NeHe ( and some books. It was OK until I start to implement the selection part. A hit never happens. I think that this may happen because I couldn't get the cursor position appropriate. Here is my code for mouse click
public void onMouseClick(object sender, MouseEventArgs e) { int xPozisyon = e.X; int yPozisyon = e.Y; ProcessSelection(xPozisyon, yPozisyon); }
I the lessons I have read they use x = event->data[AUX_MOUSEX]; y = event->data[AUX_MOUSEY]; or int xPos = LOWORD(lParam); int yPos = HIWORD(lParam); Is that the problem for me why I cannot getting a hit. I mean is there a problem with gettting the cursor position inside the OpenGL Control? Thanks for your helps and best regards.

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apocalypse_k40    122
Actually I realized that I do not to make any object selection. I need to get where the use clicked (on the scene).

Is it possible to define a reference position for making mathematical operations including the scene's rotation, transformation etc. ?

As I said before, I try to make a checkers game where the board width is 2 and height 2. I create a jagged array like :
public byte[,] boardMatrice = {{0, 2, 0, 2, 0, 2, 0, 2},
{2, 0, 2, 0, 2, 0, 2, 0},
{0, 2, 0, 2, 0, 2, 0, 2},
{0, 0, 0, 0, 0, 0, 0, 0},
{0, 0, 0, 0, 0, 0, 0, 0},
{1, 0, 1, 0, 1, 0, 1, 0},
{0, 1, 0, 1, 0, 1, 0, 1},
{1, 0, 1, 0, 1, 0, 1, 0}};

After I draw the board I place the pieces according to this matrice in which 2 is the black player and 1 is the white player.

So -assuming the board is flat- if the user clicks on the board -let's say at (0.688,0.123)- the program should know that the boardMatrice[5,0] is selected. Because the board size is (2,2) so every square size is (0.25,0.25).

So here raises 5 problems :
1- The OpenGL control's Dock property is fill. So when the user changes the size, it may not stick to the left which means -for example- 0.0 to 0.25 does not mean the bottom left square anymore. How can I overcome this?
2- How can I define a reference point which rotates, transgorms etc. with the board? It will be used to make some calculations when the board is rotated, transformed etc.
3- How can I send a ray (-line?) from this reference point to the scene, and see if it intersects with the board. If it intersects how can I get the length, angle etc. of this ray ?
4- The window coordinates' (0,0) is the upper left but for OpenGL it is lower left. How can I change the window coordinate to OpenGL coordinate?
5- If the OpenGL control's size is -let's say- (480,480) does that I mean that the cursor's actual position in -again let's say- (240,120) is (1,0.5) ?

I will appreciate any help and suggestions.


[Edited by - apocalypse_k40 on March 17, 2007 10:15:32 AM]

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Check this site out, it should answer your questions.

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