EXATAS E TECNOLÓGICAS ISSN IMPRESSO - 2359-4934 ISSN ELETRÔNICO - 2359-4942 http://dx.doi.org/10.17564/2359-4942.2018v3n2 REVISING FRAMEWORKS FOR DEVELOPING MOBILE VIRTUAL REALITY REVISANDO FRAMEWORKS PARA DESENVOLVIMENTO DE REALIDADE VIRTUAL MÓVEL REVISIÓN DE LOS ENTORNOS PARA EL DESARROLLO DE REALIDAD VIRTUAL MÓVIL Guillermo Horacio Rodriguez1 Fabio Gomes Rocha2 ABSTRACT The development of mobile virtual environments has categories so that it becomes easier to understand been enabled by recent advances in hardware and the state of art and to help identify new directions software for mobile computing. This new trend has of research. A comparison of attributes of each tech- resulted from the convergence of wear able comput- nology is also summarized. ing, wireless networking and mobile virtual reality interfaces. This work provides a survey of different mobile technologies that are useful to build virtual Keywords reality applications running through mobile devices. Our aim is to place those technologies into different Framework. Developing Mobile. Virtual Reality. Interfaces Científicas - Exatas e Tecnológicas • Aracaju • V.3 • N.2 • p. 35 - 48 • Outubro 2018 • 36 • RESUMO O desenvolvimento de ambientes virtuais móveis foi em diferentes categorias para que seja mais fácil en- possibilitado pelos recentes avanços em hardware e tender o estado da arte e ajudar a identificar novos software para computação móvel. Essa nova tendên- rumos da pesquisa. Uma comparação de atributos de cia resultou da convergência de interfaces de com- cada tecnologia também é resumida. putação portátil, redes sem fio e realidade virtual móvel. Este trabalho fornece uma pesquisa de dif- erentes tecnologias móveis úteis para criar aplicati- Palavra-chave vos de realidade virtual executados em dispositivos móveis. Nosso objetivo é colocar essas tecnologias Framework. Realidade Virtual. Desenvolvimento Mobile. Resumen El desarrollo de entornos virtuales móviles ha sido ha- tivo es colocar esas tecnologías en diferentes cate- bilitado por los recientes avances en hardware y soft- gorías para que sea más fácil comprender el estado ware para computación móvil. Esta nueva tendencia del arte y ayudar a identificar nuevas direcciones de se debe a la convergencia de la computación portátil, investigación. También se resume una comparación las redes inalámbricas y las interfaces de realidad vir- de los atributos de cada tecnología. tual móvil. Este trabajo proporciona una investigación de diferentes tecnologías móviles que son útiles para Palabra clave construir aplicaciones de realidad virtual que se eje- cutan a través de dispositivos móviles. Nuestro obje- Framework, Realidad Virtual, Desarrollo móvil Interfaces Científicas - Exatas e Tecnológicas • Aracaju • V.3 • N.2 • p. 35 - 48 • Outubro 2018 • 37 • 1 INTRODUCTION platforms. Section 3 describes frameworks for devel- oping mobile virtual reality. Section 4 described 3D Today’s mobile phones are being used as com- game development tools which integrate with mobile puters for multi-purpose functions. Not only the platforms. Section 5 compares different frameworks number of mobile Internet users is growing rapidly, analyzed. Finally, Section 6 concludes this research but also the mobile market is growing (MILOSEVIC; and identifies future lines of work. DEHGHANTANHA; KIM-KWANG, 2017). However, at the same time the market of the mobile platforms is 2 VIRTUAL REALITY ON MOBILE PLATFORM fragmented, there are many mobile operating sys- tems and programming languages. Thus, mobile de- The emergence of the Mobile Computing (MC) par- velopers need to use platform specific tools and APIs adigm has been led by the evolutions in portable com- in order to write mobile applications in different pro- puter devices technology, and the advances in wire- gramming languages on different platforms (ALLEN; less communication (DIAS JUNIOR, 2010). Constant GRAUSPERA; LUNDIRGAN, 2010). research in this area has permitted the development Reprogramming basically the same application of a great variety of portable devices that allow users into multiple mobile platforms means an increase in to work together regardless their physical location, development costs and longer development times or leading to greater freedom among users and compu- decrease in the number of supported mobile platforms tational systems. and a transfer of focus only on specific devices. The Different types of equipment such as mobile cell demand for shorter mobile application development phones with Wireless Application Protocol (WAP), process has driven the need for cross-platform solu- notebooks, palmtops, among others, have resulted in tions. The idea of cross-platform mobile programming an increased demand for new services and applica- is that with the same base-code with little or no modi- tions in the most diverse areas. The evolution of MC fications a mobile application could be published into has promoted advances in the development of new multiple mobile phone platforms. hardware and software technologies, opening a range Mobile devices have become an integral part of ev- of new applications based on wireless communication eryday lives. Particularly, virtual reality, like 3D games, resources. Among those, applications for Virtual Real- has been highly used in education and entertainment ity (VR) and/or Mixed Reality (MR) in the most diverse because everybody is able to access to mobile devic- areas such as education, entertainment, visualiza- es. A new approach that is currently taking place in tion etc., are in special evidence (PAPAGIANNAKIS; education is the use of virtual worlds and virtual-re- SINGH; MAGNENAT-THALMANN, 2009). The portabil- ality-based games. These applications allow teachers ity provided by mobile devices allows the creation of a to load courses and interact with students through the Mobile Virtual Environment to exchange experiences, virtual world. This approach is known as m-Learning. information, and images, among people, in a more at- For example, some approaches have illustrated the tractive and motivating way for the user. suitability of the framework and authoring tool for sup- However, there are some problems specifically porting users without programming skills in develop- related to mobile devices limitations, which conti- ing their own apps (MOTA et al., 2018). In this light, the nue to represent a `bottleneck’ for the creation of aim of this work is to research the state of the art in VR mobile applications. The main obstacle to be cross-platforms and their development environments. transposed in the development of applications for The remainder of the paper is organized as follows. mobile devices is their heterogeneity, characteri- Section 2 gives an overview of different mobile cross- zed by limitations in terms of processing, memory, Interfaces Científicas - Exatas e Tecnológicas • Aracaju • V.3 • N.2 • p. 35 - 48 • Outubro 2018 • 38 • and battery capacity, communication bandwidth, layouts which contain widgets such as buttons, or as well as the great variety of existing software labels. Widgets are created when the activity starts, (Windows, Symbian, Palm OS etc.). Due to those and have their own event listeners. An activity can different features, it would be necessary to deve- start another, but communication between activities lop specific VR content versions for these diverse is usually done by passing parameters. environments, in accordance with the characteris- Only one activity can have focus at a time and tics of each device. activities that are idle for a long time are killed by However, the creation of different versions mi- the Activity Manager, therefore Android applica- ght not be viable and might not reach the human tions never exit upon request from the user, condition, because of the number of platforms and they are just put in background and killed if they devices available. In this context, the development remain inactive for some time. Figure 1 describes of VR applications for mobile devices becomes the components of Android architecture based on a a challenge, especially for heterogeneous devi- Layer design pattern. ces. Subsection 3.10 shows an approach to tackle the problem of heterogeneous platforms and fra- Figure 1 – Android components meworks. 3 FRAMEWORKS TO DEVELOP MOBILE VIRTUAL REALITY Particularly, this work focuses on analyzing cross-platform native frameworks. A cross-platform native framework is software that allows a com- mon development approach across platforms but that build to an application that is indistinguishable by a user from one built with native code (ALLEN; GRAUSPERA; LUNDIRGAN, 2010). Cross-platform native frameworks let a developer to create a nati- Fonte: MOTA, 2018 ve, installable and mobile application distribution platform compatible with multiple platforms using The emulator is essentially meant to test your cross-platform APIs and usually HTML/CSS/JavaS- Android applications. It resides under the `tools/’ cript frameworks. directory. The emulator also ships with a plethora of applications like a browser, a cooler-than-traditional 3.1 ANDROID phonebook and a map application, among other fe- atures. So, even if users have not yet written an An- Android is a mobile operating system developed droid application, the emulator is a must checkout. by Google, based on a modified version of the Linux Figure 2 shows an example built in the android SDK, kernel. Its API (Application Programming Interfa- a plugin of Eclipse IDE. ce) uses the Java language and consists