Irrlicht Engine Tutorial

As always, we include the header files (conio and curses for getting - user input from the console), and use the irrlicht namespaces. We also - store a pointer to the Irrlicht device, a counter variable for changing - the creation position of a window, and a pointer to a listbox.

- - - - -

#include <irrlicht.h>
-#include <iostream>

-using namespace irr;

using namespace core;
-using namespace scene;
-using namespace video;
-using namespace io;
-using namespace gui;

#pragma comment(lib, "Irrlicht.lib")

IrrlichtDevice *device = 0;
-s32 cnt = 0;
-IGUIListBox* listbox = 0;
-

The Event Receiver is not only capable of getting keyboard and mouse - input events, but also events of the graphical user interface (gui). - There are events for almost everything: Button click, Listbox selection - change, events that say that a element was hovered and so on. To be - able to react to some of these events, we create
- an event receiver. We only react to gui events, and if it's such an - event, we get the id of the caller (the gui element which caused the - event) and get the pointer to the gui environment.

- - - - -

class MyEventReceiver : public IEventReceiver
{
public:
	virtual bool OnEvent(const SEvent& event)
	{
		if (event.EventType == EET_GUI_EVENT)
		{
			s32 id = event.GUIEvent.Caller->getID();
			IGUIEnvironment* env = device->getGUIEnvironment();

            switch(event.GUIEvent.EventType)
-            {

If a scrollbar changed its scroll position, and it is 'our' scrollbar - (the one with id 104), then we change the
- transparency of all gui elements. This is a very easy task: There is - a skin object, in which all color settings are stored. We simply go - through all colors stored in the skin and change their alpha value. -

- - - - -

case EGET_SCROLL_BAR_CHANGED:
	if (id == 104)
	{
		s32 pos = ((IGUIScrollBar*)event.GUIEvent.Caller)->getPos();
					
		for (s32 i=0; i<EGDC_COUNT ; ++i)
		{
			SColor col = env->getSkin()->getColor((EGUI_DEFAULT_COLOR)i);
			col.setAlpha(pos);
			env->getSkin()->setColor((EGUI_DEFAULT_COLOR)i, col);
		}
	}
break;

If a button was clicked, it could be one of 'our' three buttons. If - it is the first, we shut down the engine.
- If it is the second, we create a little window with some text on it. - We also add a string to the list box to log
- what happened. And if it is the third button, we create a file open - dialog, and add also this as string to the list box.
- That's all for the event receiver.

- - - - -

       case EGET_BUTTON_CLICKED:
-              if (id == 101)
-              {
-                 device->closeDevice();
-                 return true;
-              }

              if (id == 102)
-              {
-                 listbox->addItem(L"Window created");
-                 cnt += 30;
-                 if (cnt > 200) 
-                   cnt = 0;

                 IGUIWindow* window = env->addWindow(
-                       rect<s32>(100 + cnt, 100 + cnt, 300 + cnt, 200 + cnt), 
                       false, // modal?
-                       L"Test window");

                 env->addStaticText(L"Please close me", 
-                       rect<s32>(35,35,140,50),
-                       true, // border?,
-                       false, // wordwrap?
-                       window);
-
-                 return true;
-              }

              if (id == 103)
-              {
-                 listbox->addItem(L"File open");
-                 env->addFileOpenDialog(L"Please choose a file.");
-                 return true;
-              }

              break;
-          }
-       }
-       return false;
-    }
- };

Ok, now for the more interesting part. First, create the Irrlicht device. - As in some examples before, we ask the user which driver he wants to - use for this example:

The creation was successful, now we set the event receiver and store - pointers to the driver and to the gui environment.

We add three buttons. The first one closes the engine. The second creates - a window and the third opens a file open dialog. The third parameter is - the id of the button, with which we can easily identify the button in - the event receiver.

Now, we add a static text and a scrollbar, which modifies the transparency - of all gui elements. We set the maximum value of the scrollbar to 255, - because that's the maximal value for a color value.
- Then we create an other static text and a list box.

	- - - Tutorial 5.User Interface - -
- - This tutorial shows how to use the built in User Interface of the Irrlicht - Engine. It will give a brief overview and show how to create and use - windows, buttons, scroll bars, static texts and list boxes. - The program which is described here will look like this: - - - -