Reacting on userinput.

Besides the possibility to use DirectInput to retrieve keyboard, mouse and joystick feedback from the user, it's possible to use basic Windows messages to react on keyboard and mouse activity (for joysticks you need DirectInput). DirectInput can be placed in one effectobject that polls every cycle in its RenderFrame method the activity queue.

To retrieve normal Windows messages received on keyboard and/or mouse activity, first enable the MessageHandler of the effectobjects that have to receive the input by using DEMOGL_MessageHandlerEnable. Then to react on keyboard and mouse activity, you could implement something like the code snippet below, in the MessageHandler method of the effectobject which messagehandler is enabled.

// Purpose: the messagehandler of this effect. if we enable it we'll receive 
// every message posted to the window of the current app. This is handy if we want to 
// receive keyboard or mouse messages.
void
C3DView::MessageHandler(HWND hWnd, UINT uMsg, WPARAM  wParam, LPARAM  lParam)
{
	int		iX, iY;

	switch(uMsg)
	{
		case WM_MOUSEMOVE:
		{
			if(m_bLMBDown)
			{
				// user is dragging with the mouse. get x and y delta's and
				// reflect the delta's on the rotation angles of a rotating
				// object.
				
				// get X and Y
				iX=GET_X_LPARAM(lParam);
				iY=GET_Y_LPARAM(lParam);
				m_fAlpha= m_fAlpha + (float)(iY - m_iYPrev);
				m_fBeta= m_fBeta + (float)(iX - m_iXPrev);
				m_iXPrev=iX;
				m_iYPrev=iY;
			}
		};break;
		case WM_LBUTTONDOWN:
		{
			m_bLMBDown=true;
			iX=GET_X_LPARAM(lParam);
			iY=GET_Y_LPARAM(lParam);
		}; break;
		case WM_LBUTTONUP:
		{
			m_bLMBDown=false;
		};break;
		case WM_RBUTTONDOWN:
		{
			// as an example, exit the application.
			DEMOGL_ExecuteCommand("_SYSTEM;END;");
		};break;
		case WM_CHAR:
		{
			// received a character done by a keypress (in: (char)wParam)
		}; break;
		case WM_KEYDOWN:
		{
			// received a keycode done by a keypress (in: wParam)
		}; break;
	}
}

DemoGL will pass every message received to the effectobjects which messagehandlers are enabled. The developer doesn't have to pass back the messages to windows. This is done by DemoGL.