Using OGRE with GII

As mentioned in a lot of places, OGRE is a rendering library. The input system that comes with it is only suited for the demos, thus if you are making a game you want a higher quality input library.
GII is a good choice for this because it handles all the kinds of joystick, keyboard and mouse input you want. In addition to scancodes, it also passes in keyboard input in unicode, thus no problems arise with different keyboard mappings.

It also has some advantages above SDL:

  • Less overhead if you just need an input system
  • Easier to bind to an existing window than SDL (no environment variable hacks needed for one thing)


Currently, this document only describes the mapping under Linux using the GLX platform. I hope to later extend this somehow to windows and MAC.

Also, the steps described here attempt in no way to lock up the mouse inside your window or translate absolute to relative mouse movement. This can be added if you need it, but I didn't.

Using GII

Get the CVS branch 0.9 as described here http://www.ggi-project.org/packages/libgii.html (be sure to get branch 0.9 as it fixes some nasty GLX issue).

Documentation can be found here

Include the following header 

#include <ggi/gii.h>

For the GLX binding, also use 

#include <ggi/input/xwin.h>

Binding to GII

This section describes the steps needed to bind the Ogre renderwindow to the GII input system. This is probably why you are here.
No matter what the platform, the steps need to be executed after the Ogre render window was created. We let Ogre create the window instead of GII because Ogre knows specifics like the type of pixel/framebuffer format it wants.

GLX

For GLX, the process of making libGII capture events from the Ogre window is described here. Make sure you have at least Ogre 1.0.1 for this to work.

After calling Root::initialise or creating your render window, do this: 

// Initialize ggi input
            giiInit();
            
            gii_inputxwin_arg giiarg;
            mWindow->getCustomAttribute("GLXWINDOW", &giiarg.win);
            mWindow->getCustomAttribute("GLXDISPLAY", &giiarg.disp);
            GLXWindowInterface *iface;
            mWindow->getCustomAttribute("GLXWINDOWINTERFACE", &iface);
            giiarg.ptralwaysrel = false;
            giiarg.wait = false;
            giiarg.exposefunc = &exposefunc;
            giiarg.exposearg = iface;
            giiarg.gglock = 0;
            giiarg.resizefunc = &resizefunc;
            giiarg.resizearg = iface;
            
            mGIIHandle = giiOpen("input-xwin", &giiarg);
            
            /// This seems to be needed as the Expose of gii is never called
            iface->exposed(true);

GLXWindowInterface, exposefunc and resizefunc are defined like this 

class GLXWindowInterface
{
public:
    virtual ~GLXWindowInterface() = 0;
    
    virtual void exposed(bool active) = 0;
    virtual void resized(size_t width, size_t height) = 0;
};
int exposefunc(void *arg, int x, int y, int w, int h)
{
    static_cast<GLXWindowInterface*>(arg)->exposed(true);
    return 0;
}
int resizefunc(void *arg, int w, int h, gii_event *ev)
{
    static_cast<GLXWindowInterface*>(arg)->resized((size_t)w, (size_t)h);
    return 0;
}

FrameListener



To keep it simple, I have based this on the OGRE example framework. In the frameStarted of my Input FrameListener I included the following event loop. This code fragment should be platform independent: 

bool frameStarted(const FrameEvent& evt)
    {
        if(mWindow->isClosed())
            return false;
        /// GII input handling
        
        struct timeval tv;
        tv.tv_sec = 0;
        tv.tv_usec = 0; 
        gii_event_mask mask = giiEventPoll(mGIIHandle, emAll, &tv);
        
        int nevents = giiEventsQueued(mGIIHandle, emAll);
        
        while(nevents>0)
        {
            gii_event ev;
            giiEventRead(mGIIHandle, &ev, emAll);
            
            switch(ev.any.type) {
                case evKeyPress:
                case evKeyRepeat:
                    ///std::cerr << "Key pressed: " << std::hex << ev.key.sym << " " << ev.key.label << " " << convertGGIKeyToCegui(ev.key.label) << std::dec << std::endl;
                    CEGUI::System::getSingleton().injectKeyDown(convertGGIKeyToCegui(ev.key.label));
                    if(GII_UNICODE(ev.key.sym) && ev.key.sym!=127)
                        CEGUI::System::getSingleton().injectChar(ev.key.sym);
                    break;
                case evKeyRelease:
                    CEGUI::System::getSingleton().injectKeyUp(convertGGIKeyToCegui(ev.key.label));
                    break;
                case evPtrRelative:
                    CEGUI::System::getSingleton().injectMouseMove(ev.pmove.x, ev.pmove.y);
                    /// XXX wheel
                    break;
                case evPtrAbsolute:
                    CEGUI::System::getSingleton().injectMousePosition(ev.pmove.x, ev.pmove.y);
                    /// XXX wheel
                    break;
                case evPtrButtonPress:
                    CEGUI::System::getSingleton().injectMouseButtonDown(convertGGIButtonToCegui(ev.pbutton.button));
                    break;
                case evPtrButtonRelease:
                    CEGUI::System::getSingleton().injectMouseButtonUp(convertGGIButtonToCegui(ev.pbutton.button));
                    break;
                // evValAbsolute
                // evValRelative
            }
            
            nevents--;
        }        
        return true;
    }

GUI system

To actually do something with the incoming input, the incoming events are translated and passsed to the GUI library CEGUI. If you don't use this in your game, translate the events to your ingame event system in your own way, this article just demonstrates how to do the binding. 

/// Map GII mouse button to CEGUI
CEGUI::MouseButton convertGGIButtonToCegui(unsigned int buttonID)
{
    switch (buttonID)
    {
    case GII_PBUTTON_LEFT:
        return CEGUI::LeftButton;
    case GII_PBUTTON_RIGHT:
        return CEGUI::RightButton;
    case GII_PBUTTON_MIDDLE:
        return CEGUI::MiddleButton;
    default:
        return CEGUI::LeftButton;
    }
}
// Map GII keyboard key to CEGUI
unsigned int convertGGIKeyToCegui(unsigned int buttonID)
{
    using namespace CEGUI;
    switch (buttonID)
    {
    case GIIUC_Escape: return Key::Escape;
    case GIIUC_1: return Key::One;
    case GIIUC_2: return Key::Two;
    case GIIUC_3: return Key::Three;
    case GIIUC_4: return Key::Four;
    case GIIUC_5: return Key::Five;
    case GIIUC_6: return Key::Six;
    case GIIUC_7: return Key::Seven;
    case GIIUC_8: return Key::Eight;
    case GIIUC_9: return Key::Nine;
    case GIIUC_0: return Key::Zero;
    case GIIUC_Minus: return Key::Minus;
    case GIIUC_Equal: return Key::Equals;
    case GIIUC_BackSpace: return Key::Backspace;
    case GIIUC_Tab: return Key::Tab;
    case GIIUC_Q: return Key::Q;
    case GIIUC_W: return Key::W;
    case GIIUC_E: return Key::E;
    case GIIUC_R: return Key::R;
    case GIIUC_T: return Key::T;
    case GIIUC_Y: return Key::Y;
    case GIIUC_U: return Key::U;
    case GIIUC_I: return Key::I;
    case GIIUC_O: return Key::O;
    case GIIUC_P: return Key::P;
    case GIIUC_BracketLeft: return Key::LeftBracket;
    case GIIUC_BracketRight: return Key::RightBracket;
    case GIIUC_Return: return Key::Return;
    case GIIK_CtrlL: return Key::LeftControl;
    case GIIUC_A: return Key::A;
    case GIIUC_S: return Key::S;
    case GIIUC_D: return Key::D;
    case GIIUC_F: return Key::F;
    case GIIUC_G: return Key::G;
    case GIIUC_H: return Key::H;
    case GIIUC_J: return Key::J;
    case GIIUC_K: return Key::K;
    case GIIUC_L: return Key::L;
    case GIIUC_Semicolon: return Key::Semicolon;
    case GIIUC_Apostrophe: return Key::Apostrophe;
    case GIIUC_Grave: return Key::Grave;
    case GIIK_ShiftL: return Key::LeftShift;
    case GIIUC_BackSlash: return Key::Backslash;
    case GIIUC_Z: return Key::Z;
    case GIIUC_X: return Key::X;
    case GIIUC_C: return Key::C;
    case GIIUC_V: return Key::V;
    case GIIUC_B: return Key::B;
    case GIIUC_N: return Key::N;
    case GIIUC_M: return Key::M;
    case GIIUC_Comma: return Key::Comma;
    case GIIUC_Period: return Key::Period;
    case GIIUC_Slash: return Key::Slash;
    case GIIK_ShiftR: return Key::RightShift;
    case GIIUC_Multiply: return Key::Multiply;
    case GIIK_AltL: return Key::LeftAlt;
    case GIIUC_Space: return Key::Space;
    case GIIK_CapsLock: return Key::Capital;
    case GIIK_F1: return Key::F1;
    case GIIK_F2: return Key::F2;
    case GIIK_F3: return Key::F3;
    case GIIK_F4: return Key::F4;
    case GIIK_F5: return Key::F5;
    case GIIK_F6: return Key::F6;
    case GIIK_F7: return Key::F7;
    case GIIK_F8: return Key::F8;
    case GIIK_F9: return Key::F9;
    case GIIK_F10: return Key::F10;
    case GIIK_NumLock: return Key::NumLock;
    case GIIK_ScrollLock: return Key::ScrollLock;
    case GIIK_P7: return Key::Numpad7;
    case GIIK_P8: return Key::Numpad8;
    case GIIK_P9: return Key::Numpad9;
    case GIIK_PMinus: return Key::Subtract;
    case GIIK_P4: return Key::Numpad4;
    case GIIK_P5: return Key::Numpad5;
    case GIIK_P6: return Key::Numpad6;
    case GIIK_PPlus: return Key::Add;
    case GIIK_P1: return Key::Numpad1;
    case GIIK_P2: return Key::Numpad2;
    case GIIK_P3: return Key::Numpad3;
    case GIIK_P0: return Key::Numpad0;
    case GIIK_PDecimal: return Key::Decimal;
    //case GIIUC_OEM_102: return Key::OEM_102;
    case GIIK_F11: return Key::F11;
    case GIIK_F12: return Key::F12;
    case GIIK_F13: return Key::F13;
    case GIIK_F14: return Key::F14;
    case GIIK_F15: return Key::F15;
    //case GIIUC_Kana: return Key::Kana;
    //case GIIUC_ABNT_C1: return Key::ABNT_C1;
    //case GIIUC_Convert: return Key::Convert;
    //case GIIUC_NoConvert: return Key::NoConvert;
    //case GIIUC_Yen: return Key::Yen;
    //case GIIUC_ABNT_C2: return Key::ABNT_C2;
    case GIIK_PEqual: return Key::NumpadEquals;
    case GIIK_PreviousSong: return Key::PrevTrack;
    case GIIUC_At: return Key::At;
    case GIIUC_Colon: return Key::Colon;
    case GIIUC_Underscore: return Key::Underline;
    //case GIIUC_Kanji: return Key::Kanji;
    //case GIIUC_AX: return Key::AX;
    //case GIIUC_Unlabeled: return Key::Unlabeled;
    case GIIK_NextSong: return Key::NextTrack;
    case GIIK_PEnter: return Key::NumpadEnter;
    case GIIK_CtrlR: return Key::RightControl;
    case GIIK_Mute: return Key::Mute;
    case GIIK_Calc: return Key::Calculator;
    case GIIK_PlayPause: return Key::PlayPause;
    case GIIK_StopCd: return Key::MediaStop;
    case GIIK_VolumeDown: return Key::VolumeDown;
    case GIIK_VolumeUp: return Key::VolumeUp;
    case GIIK_Homepage: return Key::WebHome;
    case GIIK_PSeparator: return Key::NumpadComma;
    case GIIK_PSlash: return Key::Divide;
    case GIIK_PrintScreen: return Key::SysRq;
    case GIIK_AltR: return Key::RightAlt;
    //case GIIK_PauseCd: return Key::Pause;
    case GIIK_Stop: return Key::Pause;
    case GIIK_Home: return Key::Home;
    case GIIK_Up: return Key::ArrowUp;
    case GIIK_Prior: return Key::PageUp;
    case GIIK_Left: return Key::ArrowLeft;
    case GIIK_Right: return Key::ArrowRight;
    case GIIK_End: return Key::End;
    case GIIK_Down: return Key::ArrowDown;
    case GIIK_Next: return Key::PageDown;
    case GIIK_Insert: return Key::Insert;
    case GIIK_Delete: return Key::Delete;
    case GIIK_SuperL: return Key::LeftWindows;
    case GIIK_SuperR: return Key::RightWindow;
    case GIIK_Menu: return Key::AppMenu;
    case GIIK_Power: return Key::Power;
    case GIIK_Sleep: return Key::Sleep;
    case GIIK_Wakeup: return Key::Wake;
    case GIIK_Search: return Key::WebSearch;
    case GIIK_Favorites: return Key::WebFavorites;
    case GIIK_Refresh: return Key::WebRefresh;
    //case GIIUC_WebStop: return Key::WebStop;
    case GIIK_Forward: return Key::WebForward;
    case GIIK_Back: return Key::WebBack;
    case GIIK_Computer: return Key::MyComputer;
    case GIIK_Mail: return Key::Mail;
    case GIIK_Media: return Key::MediaSelect;
    default:
        return 0;
    }
}

<HR>
Creative Commons Copyright -- Some rights reserved.


THE WORK (AS DEFINED BELOW) IS PROVIDED UNDER THE TERMS OF THIS CREATIVE COMMONS PUBLIC LICENSE ("CCPL" OR "LICENSE"). THE WORK IS PROTECTED BY COPYRIGHT AND/OR OTHER APPLICABLE LAW. ANY USE OF THE WORK OTHER THAN AS AUTHORIZED UNDER THIS LICENSE OR COPYRIGHT LAW IS PROHIBITED.

BY EXERCISING ANY RIGHTS TO THE WORK PROVIDED HERE, YOU ACCEPT AND AGREE TO BE BOUND BY THE TERMS OF THIS LICENSE. THE LICENSOR GRANTS YOU THE RIGHTS CONTAINED HERE IN CONSIDERATION OF YOUR ACCEPTANCE OF SUCH TERMS AND CONDITIONS.

1. Definitions

  • "Collective Work" means a work, such as a periodical issue, anthology or encyclopedia, in which the Work in its entirety in unmodified form, along with a number of other contributions, constituting separate and independent works in themselves, are assembled into a collective whole. A work that constitutes a Collective Work will not be considered a Derivative Work (as defined below) for the purposes of this License.
  • "Derivative Work" means a work based upon the Work or upon the Work and other pre-existing works, such as a translation, musical arrangement, dramatization, fictionalization, motion picture version, sound recording, art reproduction, abridgment, condensation, or any other form in which the Work may be recast, transformed, or adapted, except that a work that constitutes a Collective Work will not be considered a Derivative Work for the purpose of this License. For the avoidance of doubt, where the Work is a musical composition or sound recording, the synchronization of the Work in timed-relation with a moving image ("synching") will be considered a Derivative Work for the purpose of this License.
  • "Licensor" means the individual or entity that offers the Work under the terms of this License.
  • "Original Author" means the individual or entity who created the Work.
  • "Work" means the copyrightable work of authorship offered under the terms of this License.
  • "You" means an individual or entity exercising rights under this License who has not previously violated the terms of this License with respect to the Work, or who has received express permission from the Licensor to exercise rights under this License despite a previous violation.
  • "License Elements" means the following high-level license attributes as selected by Licensor and indicated in the title of this License: Attribution, ShareAlike.

2. Fair Use Rights

Nothing in this license is intended to reduce, limit, or restrict any rights arising from fair use, first sale or other limitations on the exclusive rights of the copyright owner under copyright law or other applicable laws.

3. License Grant

Subject to the terms and conditions of this License, Licensor hereby grants You a worldwide, royalty-free, non-exclusive, perpetual (for the duration of the applicable copyright) license to exercise the rights in the Work as stated below:

  • to reproduce the Work, to incorporate the Work into one or more Collective Works, and to reproduce the Work as incorporated in the Collective Works;
  • to create and reproduce Derivative Works;
  • to distribute copies or phonorecords of, display publicly, perform publicly, and perform publicly by means of a digital audio transmission the Work including as incorporated in Collective Works;
  • to distribute copies or phonorecords of, display publicly, perform publicly, and perform publicly by means of a digital audio transmission Derivative Works.
  • For the avoidance of doubt, where the work is a musical composition:
    • Performance Royalties Under Blanket Licenses. Licensor waives the exclusive right to collect, whether individually or via a performance rights society (e.g. ASCAP, BMI, SESAC), royalties for the public performance or public digital performance (e.g. webcast) of the Work.
    • Mechanical Rights and Statutory Royalties. Licensor waives the exclusive right to collect, whether individually or via a music rights society or designated agent (e.g. Harry Fox Agency), royalties for any phonorecord You create from the Work ("cover version") and distribute, subject to the compulsory license created by 17 USC Section 115 of the US Copyright Act (or the equivalent in other jurisdictions).
    • Webcasting Rights and Statutory Royalties. For the avoidance of doubt, where the Work is a sound recording, Licensor waives the exclusive right to collect, whether individually or via a performance-rights society (e.g. SoundExchange), royalties for the public digital performance (e.g. webcast) of the Work, subject to the compulsory license created by 17 USC Section 114 of the US Copyright Act (or the equivalent in other jurisdictions).


The above rights may be exercised in all media and formats whether now known or hereafter devised. The above rights include the right to make such modifications as are technically necessary to exercise the rights in other media and formats. All rights not expressly granted by Licensor are hereby reserved.

4. Restrictions

The license granted in Section 3 above is expressly made subject to and limited by the following restrictions:

  • You may distribute, publicly display, publicly perform, or publicly digitally perform the Work only under the terms of this License, and You must include a copy of, or the Uniform Resource Identifier for, this License with every copy or phonorecord of the Work You distribute, publicly display, publicly perform, or publicly digitally perform. You may not offer or impose any terms on the Work that alter or restrict the terms of this License or the recipients' exercise of the rights granted hereunder. You may not sublicense the Work. You must keep intact all notices that refer to this License and to the disclaimer of warranties. You may not distribute, publicly display, publicly perform, or publicly digitally perform the Work with any technological measures that control access or use of the Work in a manner inconsistent with the terms of this License Agreement. The above applies to the Work as incorporated in a Collective Work, but this does not require the Collective Work apart from the Work itself to be made subject to the terms of this License. If You create a Collective Work, upon notice from any Licensor You must, to the extent practicable, remove from the Collective Work any credit as required by clause 4(c), as requested. If You create a Derivative Work, upon notice from any Licensor You must, to the extent practicable, remove from the Derivative Work any credit as required by clause 4(c), as requested.
  • You may distribute, publicly display, publicly perform, or publicly digitally perform a Derivative Work only under the terms of this License, a later version of this License with the same License Elements as this License, or a Creative Commons iCommons license that contains the same License Elements as this License (e.g. Attribution-ShareAlike 2.5 Japan). You must include a copy of, or the Uniform Resource Identifier for, this License or other license specified in the previous sentence with every copy or phonorecord of each Derivative Work You distribute, publicly display, publicly perform, or publicly digitally perform. You may not offer or impose any terms on the Derivative Works that alter or restrict the terms of this License or the recipients' exercise of the rights granted hereunder, and You must keep intact all notices that refer to this License and to the disclaimer of warranties. You may not distribute, publicly display, publicly perform, or publicly digitally perform the Derivative Work with any technological measures that control access or use of the Work in a manner inconsistent with the terms of this License Agreement. The above applies to the Derivative Work as incorporated in a Collective Work, but this does not require the Collective Work apart from the Derivative Work itself to be made subject to the terms of this License.
  • If you distribute, publicly display, publicly perform, or publicly digitally perform the Work or any Derivative Works or Collective Works, You must keep intact all copyright notices for the Work and provide, reasonable to the medium or means You are utilizing: (i) the name of the Original Author (or pseudonym, if applicable) if supplied, and/or (ii) if the Original Author and/or Licensor designate another party or parties (e.g. a sponsor institute, publishing entity, journal) for attribution in Licensor's copyright notice, terms of service or by other reasonable means, the name of such party or parties; the title of the Work if supplied; to the extent reasonably practicable, the Uniform Resource Identifier, if any, that Licensor specifies to be associated with the Work, unless such URI does not refer to the copyright notice or licensing information for the Work; and in the case of a Derivative Work, a credit identifying the use of the Work in the Derivative Work (e.g., "French translation of the Work by Original Author," or "Screenplay based on original Work by Original Author"). Such credit may be implemented in any reasonable manner; provided, however, that in the case of a Derivative Work or Collective Work, at a minimum such credit will appear where any other comparable authorship credit appears and in a manner at least as prominent as such other comparable authorship credit.

5. Representations, Warranties and Disclaimer

UNLESS OTHERWISE AGREED TO BY THE PARTIES IN WRITING, LICENSOR OFFERS THE WORK AS-IS AND MAKES NO REPRESENTATIONS OR WARRANTIES OF ANY KIND CONCERNING THE MATERIALS, EXPRESS, IMPLIED, STATUTORY OR OTHERWISE, INCLUDING, WITHOUT LIMITATION, WARRANTIES OF TITLE, MERCHANTIBILITY, FITNESS FOR A PARTICULAR PURPOSE, NONINFRINGEMENT, OR THE ABSENCE OF LATENT OR OTHER DEFECTS, ACCURACY, OR THE PRESENCE OF ABSENCE OF ERRORS, WHETHER OR NOT DISCOVERABLE. SOME JURISDICTIONS DO NOT ALLOW THE EXCLUSION OF IMPLIED WARRANTIES, SO SUCH EXCLUSION MAY NOT APPLY TO YOU.

6. Limitation on Liability.

EXCEPT TO THE EXTENT REQUIRED BY APPLICABLE LAW, IN NO EVENT WILL LICENSOR BE LIABLE TO YOU ON ANY LEGAL THEORY FOR ANY SPECIAL, INCIDENTAL, CONSEQUENTIAL, PUNITIVE OR EXEMPLARY DAMAGES ARISING OUT OF THIS LICENSE OR THE USE OF THE WORK, EVEN IF LICENSOR HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.

7. Termination

  • This License and the rights granted hereunder will terminate automatically upon any breach by You of the terms of this License. Individuals or entities who have received Derivative Works or Collective Works from You under this License, however, will not have their licenses terminated provided such individuals or entities remain in full compliance with those licenses. Sections 1, 2, 5, 6, 7, and 8 will survive any termination of this License.
  • Subject to the above terms and conditions, the license granted here is perpetual (for the duration of the applicable copyright in the Work). Notwithstanding the above, Licensor reserves the right to release the Work under different license terms or to stop distributing the Work at any time; provided, however that any such election will not serve to withdraw this License (or any other license that has been, or is required to be, granted under the terms of this License), and this License will continue in full force and effect unless terminated as stated above.

8. Miscellaneous

  • Each time You distribute or publicly digitally perform the Work or a Collective Work, the Licensor offers to the recipient a license to the Work on the same terms and conditions as the license granted to You under this License.
  • Each time You distribute or publicly digitally perform a Derivative Work, Licensor offers to the recipient a license to the original Work on the same terms and conditions as the license granted to You under this License.
  • If any provision of this License is invalid or unenforceable under applicable law, it shall not affect the validity or enforceability of the remainder of the terms of this License, and without further action by the parties to this agreement, such provision shall be reformed to the minimum extent necessary to make such provision valid and enforceable.
  • No term or provision of this License shall be deemed waived and no breach consented to unless such waiver or consent shall be in writing and signed by the party to be charged with such waiver or consent.
  • This License constitutes the entire agreement between the parties with respect to the Work licensed here. There are no understandings, agreements or representations with respect to the Work not specified here. Licensor shall not be bound by any additional provisions that may appear in any communication from You. This License may not be modified without the mutual written agreement of the Licensor and You.