Tendências e Técnicas em Realidade Virtual e Aumentada

Transcrição

1 Tendências e Técnicas em Realidade Virtual e Aumentada

2 Av. Bento Gonçalves, Setor 4 - Prédio Sala Bairro Agronomia CEP Porto Alegre - RS - Tel. (51) Fax (51) Home: sbc@sbc.org.br José Carlos Maldonado (ICMC-USP) Presidente Marcelo Walter (UFRGS) Vice-Presidente Luciano Paschoal Gaspary (UFRGS) Diretor Administrativo Paulo Cesar Masiero (ICMC-USP) Diretor de Finanças Lisandro Zambenedetti Granville (UFRGS) Diretor de Eventos e Comissões Especiais Mirella Moura Moro (UFMG) Diretora de Educação Karin Koogan Breitman (PUC-Rio) Diretora de Publicações Ana Carolina Brandão Salgado (UFPE) Diretora de Planejamento e Programas Especiais Thais Vasconcelos Batista (UFRN) Diretora de Secretarias Regionais Altigran Soares da Silva (UFAM) Diretor de Divulgação e Marketing Ricardo de Oliveira Anido (UNICAMP) Diretor de Relações Profissionais Carlos Eduardo Ferreira (USP) Diretor de Eventos Especiais Marcelo Walter (UFRGS) Diretor de Cooperação com Sociedades Científicas

3 Tendências e Técnicas em Realidade Virtual e Aumentada Publicação anual Porto Alegre v. 1, n. 1 p

4 EDITORES Robson Augusto Siscoutto José Remo Ferreira Brega CONSELHO EDITORIAL Alexandre Cardoso, UFU Edgard Afonso Lamounier Júnior, UFU José Remo Ferreira Brega, UNESP Luciano Pereira Soares, PUC RJ Robson Augusto Siscouto, UNOESTE Veronica Teichrieb, UFPE PRODUÇÃO GRÁFICA Canal 6 Projetos Editoriais - Este periódico será registro no IBICT. Dados Internacionais de Catalogação na Publicação (CIP) Tendências e Técnicas em Realidade Virtual e Aumentada. Sociedade Brasileira de Computação - SBC. -- n. 1 (2010) -. Porto Alegra, RS: a Instituição, v. Anual ISSN 1. Realidade Virtual, Realidade Aumentada I. Siscoutto, Robson. II. Brega, Jose Remo Ferreira. CDD 006 Índice para catálogo sistemático: 1. Realidade Virtual e Aumentada: Ciência da Computação 006 Este periódico foi especialmente editado, em tiragem limitada, a partir de conteúdos desenvolvidos para os minicursos apresentado durante o XIII Simpósio de Realidade Virtual e Aumentada, realizado em Uberlândia MG de 23 a 26 de Maio de 2011, promovido pela Sociedade Brasileira de Computação e organizado pela Universidade Federal de Uberlândia - UFU. Uberlândia - MG 2011 TODOS OS DIREITOS RESERVADOS: Permitida a reprodução total ou parcial desde que citada a fonte (Tendências e Técnicas em Realidade Virtual e Aumentada, Porto Alegre-RS, Brasil). Na ausência da indicação da fonte ou expressa autorização da Instituição, é proibida a sua reprodução total ou parcial, por qualquer meio ou processo, especialmente por sistemas gráficos, microfílmicos, fotográficos, reprográficos, fonográficos ou videográficos. Vedada a memorização e/ou recuperação total ou parcial, bem como a inclusão de quaisquer partes desta obra em qualquer sistema de processamento de dados. Essas proibições aplicam-se também às características da obra e à sua editoração. A violação dos direitos autorais é punível como crime (art. 184 e, do Código Penal, cf. Lei no , de ) com pena de prisão e multa, conjuntamente com busca e apreensão e indenizações diversas (arts. 122, 123, 124 e 126, da Lei no de , Lei dos Direitos Autorais).

5 Sumário Prefácio Developing Android Applications for AugmentedReality Philip Michel Duarte, Edson Alyppyo Gomes Coutinho and Selan Rodrigues dos Santos Prototipagem Rápida de Aplicações Interativas de Realidade Aumentada Claudio Kirner Desenvolvendo um Ambiente Virtual em Realidade Aumentada para Web com FLARToolKit Robson Augusto Siscoutto e Levrangeles da Silva Filho Jogos Educacionais Baseados em Realidade Aumentada e Interfaces Tangíveis Rafael Roberto, João Marcelo Teixeira, João Paulo Lima, Manoela Milena Oliveira da Silva, Eduardo Albuquerque, Daniel Alves, Veronica Teichrieb e Judith Kelner Desenvolvimento de Aplicações em Realidade Aumentada e Diminuída para iphone e ipad Luciano Silva e Ismar Frango Silveira 5

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7 Prefácio O Symposium on Virtual and Augmented Reality (SVR) é um evento promovido pela Sociedade Brasileira de Computação que integra pesquisadores e profissionais interessados em conhecer e atualizar conceitos relacionados à realidade virtual e aumentada (RVA). Tradicionalmente, o evento oferece minicursos com o objetivo de apresentar tendências e metodologias aplicadas visando promover habilidades e difusão de conhecimentos entre seus participantes. Com o intuito de continuar a democratização e a disseminação do conhecimento sobre RV e RA, neste ano de 2011, os minicursos do SVR2011 lançam mais uma obra oferecendo uma visão conceitual e tecnológica destinada ao desenvolvimento de aplicações de realidade aumentada RA. Os cinco minicursos oferecidos, forma organizados em capítulos neste livro. No primeiro capítulo é apresentado uma visão geral do processo de desenvolvimento de aplicações de Realidade Aumentada com AndAR, uma biblioteca baseada em Java que implementa a ARToolKit na plataforma Android. O segundo capítulo aborda o problema da autoria de aplicações de Realidade Aumentada, relacionado com o desenvolvimento e uso das aplicações, em diversos níveis. É descrita uma ferramenta de autoria e seu uso na prototipagem rápida de aplicações interativas de Realidade Aumentada por não programadores. O terceiro capítulo apresentar o processo de desenvolvimento de aplicações de Realidade Aumentada na web com FLAR- ToolKit, explorando suas potencialidades quanto à integração de aplicações e suporte na sua utilização em diferentes plataformas para acesso a ambientes de RA. O quarto capítulo apresenta os conceitos básicos sobre Realidade Aumentada, interfaces tangíveis e jogos para educação de modo que a integração destes possa melhorar a experiência de alunos em sala de aula. O quinto e ultimo capítulo, detalha a organização funcional das arquiteturas do iphone e ipad, bem como seus ambientes e ferramentas de programa- 7

8 ção, detalhando algumas aplicações em Realidade Aumentada e Diminuída para ambas as plataformas. Esta obra foi o resultado do trabalho de 16 autores da comunidade brasileira de RVA e constitui uma referência para atualizações tanto por profissionais quanto por pesquisadores que queiram conhecer estas tendências e técnicas de RVA, além de ser útil como porta de entrada para estudantes, iniciantes e profissionais de outras áreas do conhecimento interessados em ingressar no fascinante mundo da tecnologia de realidade virtual e aumentada. Agradecemos a todos que colaboraram com a realização dos minicursos e com a edição deste livro. Desejamos a todos uma excelente leitura! Os organizadores Robson Augusto Siscoutto - robson.siscoutto@unoeste.br José Remo Ferreira Brega - remo@fc.unesp.br 8

9 Developing Android Applications for AugmentedReality Philip Michel Duarte, Edson Alyppyo Gomes Coutinho and Selan Rodrigues dos Santos Departamento de Informática e Matemática Aplicada (DIMAp) Universidade Federal do Rio Grande do Norte (UFRN) Natal RN Brazil {philipmichelduarte,alyppyo}@gmail.com and selan@dimap.ufrn.br Abstract In this chapter we present an overview of the development process of an Augmented Real ity (AR) application with AndAR, a Java based software library that implements ARToolkit on the Android platform. This example application recognizes markers and superimpose images over live video of the environment. To make this possible, first we present some basic concepts related to the development of mobile applications on the Android platform, Augmented Reality, and the library AndAR. After that, we provide a detailed step by step explanation about the application s implementation. 1. Android Android is an open platform for mobile development which was designed to abstract the differences between platforms and to provide a uniform use experience. It was acquired by Google in 2005 with the objective of being an alternative to mobile application devel-opment. Since then Android has been growing fast and incorporating a lot of different features such as multi-touch, multitasking and Virtual Private Network (VPN) support. JPG, PNG and GIF), SQLite, rich development environment, application framework, op timized graphics and another features that are hardware dependant. Figure 1 illustrates the Android Architeture, its layers and its components. 9

10 Tendências e Técnicas e Realidade Virtual e Aumentada, Porto Alegre, v. 2, n. 1, p. 9-28, jan./dez DUARTE, Philip Michel; COUTINHO, Edson Alyppyo Gomes; SANTOS, Selan Rodrigues dos. Developing Android Applications for AugmentedReality Figure 1. The Android s Architeture. Source: developer.android.com. Sometimes people may get confused when they try to define Android. Android depends on the Linux kernel for core systems, but it is not considered embedded Linux because the standard Linux utilities, such as X-Windows and GNU C libraries, are not supported. We write Android applications in the Java language, but they will not run within a Java ME virtual machine. Furthermore, Java-compiled classes and executables will not run natively in Android [Meier 2010], so we can not use standard Java libraries like Swing. Android has its own libraries, optimized for usage in an embedded environ ment. Android is also not a Google s answer to the iphone. Android is an open-source software stack produced by the Open Handset Alliance and designed to operate on any device that meets the requirements, while the iphone is a proprietary platform released by Apple [Meier 2010]. 1. Why choose Android? According to odesk s online employment report for October 2010 [odesk 2010], the demand for Android developers has increased by 710% when compared with the same month in last year. This means just one thing: a new market trend. In 2010, Android based mobile phones sales has passed iphone unit sales. All these facts are a direct re-sult of a well designed platform that daily attracts an incresing number of developers and users. 10

11 Tendências e Técnicas e Realidade Virtual e Aumentada, Porto Alegre, v. 2, n. 1, p. 9-28, jan./dez DUARTE, Philip Michel; COUTINHO, Edson Alyppyo Gomes; SANTOS, Selan Rodrigues dos. Developing Android Applications for AugmentedReality Another appealing aspect of Android is its online store: the Android Market (market.android.com). There are a lot of applications (or just apps ) available to all kinds of customer. The applications are divided by categories and can be found separated in free or paid categories. On the website you can find the most popular appli cations featured, and the number of applications available are growing continuously. In fact, this number has risen almost fivefold in less than one year (see Figure 2). Figure 2. Number of apps available on Android Market. Source: appbrain.com. 2. Augmented Reality Augmented Reality (AR) is a growing area in Virtual Reality (VR) research. AR sys tems generate composite views for the user, a combination of the real scene viewed by the user and a virtual scene generated by the computer that augments this scene with some additional information. The principal function of AR is to enhance the user s per formance and perception of the world [Vallino 1988]. The goal of AR is to create the sensation that virtual objects are present in the real world. So, AR is most effective when virtual elements are added in real time. Because of this it is generally used in digital video image. The simplest example of AR is overlaying a 2D image on a digital video [Cawood and Fiala 2008]. However you may use 3D models as well, how we will show you in the next sections. 11

12 Tendências e Técnicas e Realidade Virtual e Aumentada, Porto Alegre, v. 2, n. 1, p. 9-28, jan./dez DUARTE, Philip Michel; COUTINHO, Edson Alyppyo Gomes; SANTOS, Selan Rodrigues dos. Developing Android Applications for AugmentedReality When virtual objects are added to a scene, it is known as visual AR. AR elements are not visible to the naked eye so we need some sort of display to see them. This display can be a simple computer monitor or a television, or more sophisticated devices like a head-mounted display (HMD). With the advance of the technology, new interfaces are becoming available. Figure 3. Examples of fiducial marker. Figure 4. A model 3D renderized above a marker. Source: computerarts.co.uk. However, one characteristic does not change: the necessity of an indication of the place where you want to add information in a digital image. In general, we indicate it with AR markers. The simplest form of marker is a unique pattern that is visible to the AR camera and can be identified. This marker, as known as fiducial marker (see Figure 3), will be used like reference to the AR system software that will renderize the object associated to it. Fiducial means the markers are used as a trusted reference. Figure 4 shows a model 3D renderized after the AR system had recognized the marker. It is possible create AR effects without markers. This is known as markerless AR. To substitute the markers, you can track the position of LEDs or another reflexive objects, like balls. You can also use natural features of the scene, like corners of a window or energy switches instead of the markers. Another possibility is the use of textures like markers. 12

13 Tendências e Técnicas e Realidade Virtual e Aumentada, Porto Alegre, v. 2, n. 1, p. 9-28, jan./dez DUARTE, Philip Michel; COUTINHO, Edson Alyppyo Gomes; SANTOS, Selan Rodrigues dos. Developing Android Applications for AugmentedReality 2.1. Augmented Reality Application Domains AR can be applied in a lot of different domains and the researchers have proposed some ideas that will help the profissionals of many different areas. We will see some examples of these ideas now. The medical area can be considered the most important domain of AR applica tion. With the facilities that the AR systems can bring doctors can not only increase their accuracy in the diagnostic but can get it faster too. Pre-operative imaging studies of the patient can provide the surgeon with the necessary of internal anatomy, how is illustrated by Figure 5. Figure 5. AR applied on medical field. Source: University of Rochester. Military area also can be beneficiated. They have been using displays in cockpits that presents information to the pilot on the windshield of the cockpit or the visor of their flight helmet. AR can be applied in the training as well. The soldiers can visualize many precise information about the place where they are and about the groups, choosing the best strategy for the moment (Figure 6). 13

14 Tendências e Técnicas e Realidade Virtual e Aumentada, Porto Alegre, v. 2, n. 1, p. 9-28, jan./dez DUARTE, Philip Michel; COUTINHO, Edson Alyppyo Gomes; SANTOS, Selan Rodrigues dos. Developing Android Applications for AugmentedReality Figure 6. AR applied to military training. Source: augmented-reality.com. We can use AR for architecture and urban planning as well. Figure 7 repre sents the ARTHUR project from the University College London. In this project, people use some special glasses to visualize and discuss models in design meetings. The virtual models can be manipulated and the interface can develop a series of simulations and visu alisations of aspects of building performance. This interface was especially designed for interactive use and is a easy way to visualize the entire project in group [Penn et al. 2004]. Figure 7. AR applied to architetural design. Source: UCL Bartlett School of Graduate Studies. These are just some projects in AR area and you can easily find a big variety of similar projects on the internet. The area is growing fast, and the tendency is to carry on this way in the next years, which means that more ideas on the area will appear very soon. 14

15 Tendências e Técnicas e Realidade Virtual e Aumentada, Porto Alegre, v. 2, n. 1, p. 9-28, jan./dez DUARTE, Philip Michel; COUTINHO, Edson Alyppyo Gomes; SANTOS, Selan Rodrigues dos. Developing Android Applications for AugmentedReality 2.2. ARToolKit ARToolKit is a software library for building Augmented Reality (AR) applications that involve the overlay of virtual imagery on the real world. We just have to use a marker and one camera. When the user moves the marker in front of the camera, the virtual character renderized moves with it and appears attached to the real object. One of the key difficulties in developing Augmented Reality applications is the problem of tracking the users viewpoint. In order to know from what viewpoint to draw the virtual imagery, the application needs to know where the user is looking in the real world. ARToolKit uses computer vision algorithms to solve this problem. The ARToolKit video tracking libraries calculate the real camera position and orientation relative to physi cal markers in real time. This enables the easy development of a wide range of Augmented Reality applications. Some of the features of ARToolKit [ARToolKit 2011] include: Single camera position/orientation tracking; Tracking code that uses simple black squares; The ability to use any square marker patterns; Easy camera calibration code; Fast enough for real time AR applications; SGI IRIX, Linux, MacOS and Windows Operational System distributions; Distributed with complete source code. 3. AndAR AndAR is a library that empowers Android applications with Augmented Reality features. The whole project is released under the GNU General Public License (GPL). AndAR is, essentially, a ARToolKit port for Java under the Android platorm Preparing Our Development Environment For Android development, we are going to need the Eclipse IDE, the ADT plugin, the Android SDK and an Android Virtual Device. The Eclipse IDE can be downloaded free of charge from Both the ADT plugin and the latest Android SDK can be downloaded from the Android developer portal at android.com/in dex.html. The Android Virtual Device can be downloaded from the Android SDK Man ager, which comes with the SDK itself. The source code of the An- 15

16 Tendências e Técnicas e Realidade Virtual e Aumentada, Porto Alegre, v. 2, n. 1, p. 9-28, jan./dez DUARTE, Philip Michel; COUTINHO, Edson Alyppyo Gomes; SANTOS, Selan Rodrigues dos. Developing Android Applications for AugmentedReality dar project, along with the examples, can be downloaded directly from the SVN server, as shown below: svn checkout andar-read-only 3.2. Architecture of an AndAR Application AndAR is an Augmented Reality Framework for Android. It offers a pure Java, object-oriented API. The figure below shows a simplified class diagram of an application that makes use of AndAR. Figure 8. Class diagram of an AndAR application Every Android application consists of one or more Activities. An Activity is a vi sual user interface, targeted to a single purpose. Only one may be active at a time. AndAR provides a special Activity class, AndARActivity, which takes care of Augmented Real ity related features such as opening the camera, detecting the markers and displaying the video stream. One must extend AndARActivity in order to create an Augmented Reality application. The AndARActivity class also offers a method that allows the application to take screenshots. On the diagram (see Figure 1.8), the extended AndARActivity class is called CustomActivity. It must implement the method oncreate and register the objects that AndAR will process. The objects processed by AndAR are instances of classes which extend ARObject. The ARObject is an abstract class that represents an association between a marker and a 3D object. It receives the name of the marker as an argument on it s constructor 16

17 Tendências e Técnicas e Realidade Virtual e Aumentada, Porto Alegre, v. 2, n. 1, p. 9-28, jan./dez DUARTE, Philip Michel; COUTINHO, Edson Alyppyo Gomes; SANTOS, Selan Rodrigues dos. Developing Android Applications for AugmentedReality and must implement two methods: init and draw. The init method is used to initialize any members that may need a working OpenGL context. The draw is called by AndAR whenever the object associated with a specific marker needs to be rendered. Rendering with AndAR is provided through OpenGL ES 1.0. In order to draw a custom object, the method draw has to be overridden. Before this method is invoked a transformation matrix will already have been applied. This means the object will be alligned to the marker, without any further steps. This method will not be invoked, if the marker belonging to this object is not visible. The class ARRenderer is reponsible for the rendering that is not associated with AndAR markers. If you want to mix augmented with non augmented 3D objects you may provide a class implementing the OpenGLRenderer interface. There are three methods defined by this interface. initgl being called only once, when the OpenGL surface is initialized. Whereas setupenv is called once before the augmented objects are drawn. It can be used to issue OpenGL commands that shall effect all ARObjects, like initializing the lighting. In the draw method you may draw any non augmented 3D objects. It will be called once for every frame. Specifying such the described renderer is optional Using Our Own Markers Using your own markers with AndAR is easy. Just as with ARToolKit, each marker corre sponds to a file containing the necessary information for AndAR to identify the markers. Each marker file must be placed inside the assets folder of the Eclipse project. The file name corresponding to the marker must be passed as an argument in the AR- Object con structor in order to associate a marker with an object. In order to generate the marker files, one may proceed just as with ARToolKit, using the mk_patt program Programming in AndAR In order to illustrate the concepts regarding the development of Augmented Reality ap-plications in Android, we provide an in-depth walkthrough of a simple application using AndAR called ObjViewer. The purpose of this application is showing the reader how to develop a simple, yet fun AR application for Android with AndAR. The ObjViewer al lows the user to visualize 3D models built with modelling packages such as Blender or 3DS Max in an Augmented Reality context. One thing to be mentioned is that this tutorial needs an actual Android device to be properly tested, since the current Android Emulator does not feature camera support. 17

18 Tendências e Técnicas e Realidade Virtual e Aumentada, Porto Alegre, v. 2, n. 1, p. 9-28, jan./dez DUARTE, Philip Michel; COUTINHO, Edson Alyppyo Gomes; SANTOS, Selan Rodrigues dos. Developing Android Applications for AugmentedReality Step I -Planning Our App Android applications are made up of activities. Each activity manages and exibits a set of views and controls. As a rough idea, we may think of activities as realizations of use-cases from the Unified Modelling Language (UML). For the ObjViewer, we will need only one activity, which will be responsible for rendering the current frame as captured by the camera and overlaying it with the AR objects. Let us create a new android project from the Eclipse interface and name the activ ity something you like. We will use through this tutorial the name ObjActivity. You will end up with something like the source code in Figure 9. public class ObjActivity extends Activity { / Called when the activity is first created. public void oncreate ( Bundle savedinstancestate ){ super. oncreate ( savedinstancestate ); setcontentview ( R. layout. main ); } } Figure 9. Class ObjActivity. Now we must prepare the project for AndAR. There are three ways of adding An dar to our project. The first and most cumbersome is adding each of the source files to our project. The second is compiling the source yourself and generate a AndAR. jar file, which is a better approach. What we are going to do is use an already provided An-dAR.jar file, which can be found in the lib directory of the AndARModelViewer example (included in AndAR). Open up your favorite SVN client and download the source code of the AndAR project. Once the download is finished, we must add the AndAR.jar file to the CLASS PATH of our project. Right-click on the project, select Properties. Go for Java Build Path on the left menu, and pick the Libraries tab. Here, click on Add External Jar and browse through the directories to the andar-read-only/andarmodelviewer/ lib/ AndAR.jar file. After this step, we are all set. Now refer to code presented. Our app will need an Augmented Reality view, which is what the AndAR provides. Thus, our activity needs to extend AndARActivity, and not Activity. We must also call startpreview at the end of the oncreate method, in order to start fetching frames from the camera. Once you change the superclass and correct the imports, Eclipse will complain the method uncaughtexception isn t imple mented. It is an abstract method from AndARActivity, called whenever AndAR detects a severe exception on one of it s threads. We must finish the application when we receive such call (see Figure 10). 18

19 Tendências e Técnicas e Realidade Virtual e Aumentada, Porto Alegre, v. 2, n. 1, p. 9-28, jan./dez DUARTE, Philip Michel; COUTINHO, Edson Alyppyo Gomes; SANTOS, Selan Rodrigues dos. Developing Android Applications for AugmentedReality public class ObjActivity extends AndARActivity { / Called when the activity is first created. public void oncreate ( Bundle savedinstancestate ){ super. oncreate ( savedinstancestate ); startpreview () ; public void uncaughtexception ( Thread arg0, Throwable arg1 ){ finish () ; } } Figure 10. Class ObjActivity modified. This code should already compile and execute. After deploying the application into an Android device, one should see the frames captured by the camera. No augmented reality feature is displayed, however. That is due to the fact that we did not register any objects to be detected by AndAR at all. On Step II we will go through the details of setting up lights and render states in OpenGL, and on Step III we will learn how to actually load, register and display 3D models Step II -Setting Up The Scene It is time to set up the scene. Thus, what we want to do in this step is setup the lighting of our scene. Granted, the 3D objects will be displayed in an augmented reality context. But the same can not be said about the lights. AndAR will not detect light sources on the frames captured by the camera, and we must set those manually if we expect to see our objects. AndAR provides an interface, called OpenGLRenderer, which we can imple ment in order to detect and react to specific rendering events. Specifically, it has 3 meth ods: initgl, setupenv and draw. The initgl method is called once the OpenGL surface is created. The setupenv method is called just before an AR object is rendered. The draw method is called at the end of the rendering process. We will use the OpenGLRenderer to setup our lighting. We will use the initgl method to setup a few OpenGL states that remain unchanged throughout the application, such as face-culling, smooth shading and depth testing. The setupenv will be mainly used to setup the light. We also disable texturing on setupenv, since we won t be loading any textures. We will leave the draw method empty, since we won t be doing any non-ar rendering this time. The code listing in Figure 11 shows how we setup our scene. One thing to keep in mind are the FloatBuffers. On regular OpenGL with C/C++, one need not deal with them. They are allocated on native memory, and act as an optimization often made by Java ports of OpenGL, preventing and intermediary copy from managed arrays to native memory. 19

20 Tendências e Técnicas e Realidade Virtual e Aumentada, Porto Alegre, v. 2, n. 1, p. 9-28, jan./dez DUARTE, Philip Michel; COUTINHO, Edson Alyppyo Gomes; SANTOS, Selan Rodrigues dos. Developing Android Applications for AugmentedReality public class CustomRenderer implements OpenGLRenderer { // Light definitions private float [] ambientlight1 = {.3 f,.3 f,.3 f,1f }; private float [] diffuselight1 = {.7 f,.7 f,.7 f,1f }; private float [] specularlight1 = {0.6 f, 0.6 f, 0.6 f,1f }; private float [] lightposition1 = {20.0 f, 40.0f,100.0 f,1 f }; private FloatBuffer lightpositionbuffer1 = GraphicsUtil. makefloatbuffer ( lightposition1 ); private FloatBuffer specularlightbuffer1 = GraphicsUtil. makefloatbuffer ( specularlight1 ); private FloatBuffer diffuselightbuffer1 = GraphicsUtil. makefloatbuffer ( diffuselight1 ); private FloatBuffer ambientlightbuffer1 = GraphicsUtil. makefloatbuffer ( ambientlight1 ); // Do non Augmented Reality stuff here. Will be called once after all AR objects have // been drawn. The transformation matrices may have to be reset. public final void draw ( GL10 gl ){} // Directly called before each object is drawn. Used to setup lighting and // other OpenGL specific things. public final void setupenv ( GL10 gl ){ gl. glenable ( GL10. GL_LIGHTING ); gl. gllightfv ( GL10. GL_LIGHT1, GL10. GL_AMBIENT, ambientlightbuffer1 ); gl. gllightfv ( GL10. GL_LIGHT1, GL10. GL_DIFFUSE, diffuselightbuffer1 ); gl. gllightfv ( GL10. GL_LIGHT1, GL10. GL_SPECULAR, specularlightbuffer1 ); gl. gllightfv ( GL10. GL_LIGHT1, GL10. GL_POSITION, lightpositionbuffer1 ); gl. glenable ( GL10. GL_LIGHT1 ); gl. gldisableclientstate ( GL10. GL_TEXTURE_COORD_ARRAY ); gl. gldisable ( GL10. GL_TEXTURE_2D ); } } } // Called once when the OpenGL Surface was created. public final void initgl ( GL10 gl ){ gl. gldisable ( GL10. GL_COLOR_MATERIAL ); gl. glenable ( GL10. GL_CULL_FACE ); gl. glshademodel ( GL10. GL_SMOOTH ); gl. gldisable ( GL10. GL_COLOR_MATERIAL ); gl. glenable ( GL10. GL_LIGHTING ); gl. glenable ( GL10. GL_CULL_FACE ); gl. glenable ( GL10. GL_DEPTH_TEST ); gl. glenable ( GL10. GL_NORMALIZE ); Figure 11. Class CustomRenderer Now that we already have our CustomRenderer implemented, it is time to make use of it! Open up ObjActivity.java and locate the oncreate method. Here, instanciate a CustomRenderer object and pass it as the sole argument of the method setnonarrenderer of the AndARActivity super class. You will end up with something like the code in Figure 12. public void oncreate ( Bundle savedinstancestate ){ super. oncreate ( savedinstancestate ); CustomRenderer renderer = new CustomRenderer () ; super. setnonarrenderer ( renderer ); startpreview () ; } Figure 12. Method oncreate 20