9 replies to this topic

[littletray26]

Hey GameDev

I've been doing a bit of 3D programming lately, and about 10 minutes ago decided I felt like making a small 2D application.

This was all well and good until I tried to make a sprite follow the mouse coords. This problem I would say is affecting all my sprites positions but I only noticed it when I was using it to track my mouse. The texture is not drawing where it should be. Now my first assumption is a problem with the size of my back buffer in relation to my window size. The back buffer and window size are both set to 800 x 600 and I've heard you're supposed to do something to compensate for the window borders but I don't know what that is exactly. I'll show you a screen show of the difference of coords to mouse. It seems the further down I move the mouse, the more it the mouse is close to the textures middle (where it should be)

If it makes any difference, I'm tracking mouse movement with GetCursorPos(). The sprite is 50 x 50

sprite->Draw(test, NULL, &D3DXVECTOR3(0, 0, 0),
	 &D3DXVECTOR3(mousePos.x - 25, mousePos.y - 25, 0),
	 D3DCOLOR_XRGB(255, 255, 255));

Don't mind my bad quality sprite. It was just something I put together to see if it was working. The green mouse represents my cursor as it doesn't show up in screenshots.

Attached Thumbnails

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[littletray26]

I confirmed that it's because of the Windows Borders by changing it from WS_OVERLAPPEDWINDOW to WS_POPUP and then it's fine.

So the question is now, how do I combat the effect of the Window borders?

[littletray26]

BUMP

[littletray26]

I really need this answer and don't know what to google for it. Anybody?

[RulerOfNothing]

Well, it clearly states that GetCursorPos returns the mouse position in screen co-ordinates, so yes, you do need to account for the position of the window's client area. As it turns out, there is a function that will turn screen co-ordinates into client co-ordinates, called ScreenToClient. Does this help?

[littletray26]

Does this help?

Nah, that didn't fix the problem but thank you for replying

[RulerOfNothing]

To be more specific, GetCursorPos and ScreenToClient both take pointers to Point structures, so if you used:
GetCursorPos(&mousePos);
ScreenToClient(hWnd, &mousePos);
where hWnd is the handle of your main window, then you can use mousePos without changing the co-ordinates.

[littletray26]

To be more specific, GetCursorPos and ScreenToClient both take pointers to Point structures, so if you used:
GetCursorPos(&mousePos);
ScreenToClient(hWnd, &mousePos);
where hWnd is the handle of your main window, then you can use mousePos without changing the co-ordinates.

Yeah I read the link. Thanks but that didn't work :/

[Erik Rufelt]

AdjustWindowRectEx is what you need, if you want to create a window that has exactly a 800x600 (or other predefined) client area.
http://msdn.microsoft.com/en-us/library/windows/desktop/ms632667%28v=vs.85%29.aspx

Alternatively create your window first, then use GetClientRect to get the actual client-area and create a matching back-buffer (which won't be the same size as the window dimensions).

[littletray26]

AdjustWindowRectEx is what you need, if you want to create a window that has exactly a 800x600 (or other predefined) client area.

That did it! Thank you so much