International Journal of Computer Games Technology The latest articles from Hindawi Publishing Corporation © 2015 , Hindawi Publishing Corporation . All rights reserved. Development of a Car Racing Simulator Game Using Artificial Intelligence Techniques Mon, 16 Nov 2015 12:27:47 +0000 This paper presents a car racing simulator game called Racer, in which the human player races a car against three game-controlled cars in a three-dimensional environment. The objective of the game is not to defeat the human player, but to provide the player with a challenging and enjoyable experience. To ensure that this objective can be accomplished, the game incorporates artificial intelligence (AI) techniques, which enable the cars to be controlled in a manner that mimics natural driving. The paper provides a brief history of AI techniques in games, presents the use of AI techniques in contemporary video games, and discusses the AI techniques that were implemented in the development of Racer. A comparison of the AI techniques implemented in the Unity platform with traditional AI search techniques is also included in the discussion. Marvin T. Chan, Christine W. Chan, and Craig Gelowitz Copyright © 2015 Marvin T. Chan et al. All rights reserved. Game Factors and Game-Based Learning Design Model Tue, 04 Aug 2015 12:44:07 +0000 How to design useful digital game-based learning is a topic worthy of discussion. Past research focused on specific game genres design, but it is difficult to use when the target game genre differs from the default genres used in the research. This study presents macrodesign concepts that elucidates 11 crucial game-design factors, including game goals, game mechanism, game fantasy, game value, interaction, freedom, narrative, sensation, challenges, sociality, and mystery. We clearly define each factor and analyze the relationships among the 11 factors to construct a game-based learning design model. Two application examples are analyzed to verify the usability of the model and the performance of these factors. It can assist educational game designers in developing interesting games. Yen-Ru Shi and Ju-Ling Shih Copyright © 2015 Yen-Ru Shi and Ju-Ling Shih. All rights reserved. Procedural Content Graphs for Urban Modeling Wed, 17 Jun 2015 10:02:27 +0000 Massive procedural content creation, for example, for virtual urban environments, is a difficult, yet important challenge. While shape grammars are a popular example of effectiveness in architectural modeling, they have clear limitations regarding readability, manageability, and expressive power when addressing a variety of complex structural designs. Moreover, shape grammars aim at geometry specification and do not facilitate integration with other types of content, such as textures or light sources, which could rather accompany the generation process. We present procedural content graphs, a graph-based solution for procedural generation that addresses all these issues in a visual, flexible, and more expressive manner. Besides integrating handling of diverse types of content, this approach introduces collective entity manipulation as lists, seamlessly providing features such as advanced filtering, grouping, merging, ordering, and aggregation, essentially unavailable in shape grammars. Hereby, separated entities can be easily merged or just analyzed together in order to perform a variety of context-based decisions and operations. The advantages of this approach are illustrated via examples of tasks that are either very cumbersome or simply impossible to express with previous grammar approaches. Pedro Brandão Silva, Elmar Eisemann, Rafael Bidarra, and António Coelho Copyright © 2015 Pedro Brandão Silva et al. All rights reserved. Schoolcube: Gamification for Learning Management System through Microsoft SharePoint Wed, 03 Jun 2015 05:58:59 +0000 A Learning Management System (LMS) is a system which acts as an integrated platform for the management of the learning process used to facilitate the process of communication between students and instructors. Although LMS is considered an important element in learning, most students do not utilise the system to its fullest extent, finding it more convenient if the activities carried out on the system are done outside the system. These factors have contributed to the issues as to why LMSs are not being used effectively and efficiently. With the accelerating pace of information technology, educational institutions should attempt to revolutionise their teaching techniques. Furthermore, combining gaming concepts can potentially increase the LMS’s usability level helping to foster healthy competition among students and increase their interest in their daily learning. With regard to this objective, a prototype was developed as a proof of concept. The prototype is a web-based software and can be accessed via the Internet at all times. The teacher monitors the students’ performance through the analysis of test results or tutorials conducted by the system. In conclusion, this study will present the modules that have been built into the system that could improve the overall process of education. Mohd Amir Azmi and Dalbir Singh Copyright © 2015 Mohd Amir Azmi and Dalbir Singh. All rights reserved. Organizational Gameplay: The Player as Designer of Character Organizations Mon, 11 May 2015 07:26:17 +0000 Looking at the ways in which players interact with computer games (the gameplays), we perceive predominance of character-centered and/or microcontrolled modes of interaction. Despite being well established, these gameplays tend to structure the games in terms of challenges to be fulfilled on an individual basis, or by thinking collectively but having to microcontrol several characters at the same time. From this observation, the paper presents a complementary gameplay in which the player is urged to face collective challenges by designing character organizations. The basic idea is to make the player structure and control group of characters by defining organizational specifications (i.e., definitions of roles, collective strategies, and social norms). During the game, commanded by the player, artificial agents are then instantiated to play the roles and to follow the strategies and norms as defined in the organizational specification. To turn the idea into practice, the paper proposes an abstract architecture comprising three components or layers. This architecture is materialized in a proof of concept prototype that combines the Minecraft game server, JADE agent platform, and MOISE+ organizational model. Variations and possibilities are discussed and the proposal is compared to related work in the literature. Luciano R. Coutinho, Victor M. Galvão, Antônio de Abreu Batista Jr., Bruno Roberto S. Moraes, and Márcio Regis M. Fraga Copyright © 2015 Luciano R. Coutinho et al. All rights reserved. Quality Measures for Improving Technology Trees Tue, 28 Apr 2015 09:21:00 +0000 The quality of technology trees in digital games can be improved by adjusting their structural and quantitative properties. Therefore, there is a demand for recognizing and measuring such properties. Part of the process can be automated; there are properties measurable by computers, and analyses based on the results (and visualizations of them) may help to produce significantly better technology trees, even practically without extra workload for humans. In this paper, we introduce useful technology tree properties and novel measuring features implemented into our software tool for manipulating technology trees. Teemu J. Heinimäki and Tapio Elomaa Copyright © 2015 Teemu J. Heinimäki and Tapio Elomaa. All rights reserved. A Comprehensive Study on Pathfinding Techniques for Robotics and Video Games Thu, 02 Apr 2015 06:52:26 +0000 This survey provides an overview of popular pathfinding algorithms and techniques based on graph generation problems. We focus on recent developments and improvements in existing techniques and examine their impact on robotics and the video games industry. We have categorized pathfinding algorithms based on a 2D/3D environment search. The aim of this paper is to provide researchers with a thorough background on the progress made in the last 10 years in this field, summarize the principal techniques, and describe their results. We also give our expectations for future trends in this field and discuss the possibility of using pathfinding techniques in more extensive areas. Zeyad Abd Algfoor, Mohd Shahrizal Sunar, and Hoshang Kolivand Copyright © 2015 Zeyad Abd Algfoor et al. All rights reserved. Artificial Intelligence in Video Games: Towards a Unified Framework Thu, 12 Mar 2015 10:00:52 +0000 With modern video games frequently featuring sophisticated and realistic environments, the need for smart and comprehensive agents that understand the various aspects of complex environments is pressing. Since video game AI is often specifically designed for each game, video game AI tools currently focus on allowing video game developers to quickly and efficiently create specific AI. One issue with this approach is that it does not efficiently exploit the numerous similarities that exist between video games not only of the same genre, but of different genres too, resulting in a difficulty to handle the many aspects of a complex environment independently for each video game. Inspired by the human ability to detect analogies between games and apply similar behavior on a conceptual level, this paper suggests an approach based on the use of a unified conceptual framework to enable the development of conceptual AI which relies on conceptual views and actions to define basic yet reasonable and robust behavior. The approach is illustrated using two video games, Raven and StarCraft: Brood War. Firas Safadi, Raphael Fonteneau, and Damien Ernst Copyright © 2015 Firas Safadi et al. All rights reserved. Real-Time Human Motion Capture Driven by a Wireless Sensor Network Wed, 18 Feb 2015 11:38:57 +0000 The motion of a real object model is reconstructed through measurements of the position, direction, and angle of moving objects in 3D space in a process called “motion capture.” With the development of inertial sensing technology, motion capture systems that are based on inertial sensing have become a research hot spot. However, the solution of motion attitude remains a challenge that restricts the rapid development of motion capture systems. In this study, a human motion capture system based on inertial sensors is developed, and the real-time movement of a human model controlled by real people’s movement is achieved. According to the features of the system of human motion capture and reappearance, a hierarchical modeling approach based on a 3D human body model is proposed. The method collects articular movement data on the basis of rigid body dynamics through a miniature sensor network, controls the human skeleton model, and reproduces human posture according to the features of human articular movement. Finally, the feasibility of the system is validated by testing of system properties via capture of continuous dynamic movement. Experiment results show that the scheme utilizes a real-time sensor network-driven human skeleton model to achieve the accurate reproduction of human motion state. The system also has good application value. Peng-zhan Chen, Jie Li, Man Luo, and Nian-hua Zhu Copyright © 2015 Peng-zhan Chen et al. All rights reserved. Mining Experiential Patterns from Game-Logs of Board Game Thu, 22 Jan 2015 10:06:10 +0000 In board games, game-logs record past game processes, which can be regarded as an accumulation of experience. Similar to a real person, a computer player can gradually increase its skill by learning from game-logs. Therefore, the game becomes more interesting. This paper proposes an extensible approach to mine experiential patterns from increasing game-logs. The computer player improves its strategies by utilizing these growing patterns, just as it acquires experience. To evaluate the effect and performance of the approach, we designed a sample board game as a test platform and elaborated an experiment consisting of a series of tests. Experimental results show that our approach is effective and efficient. Liang Wang, Yu Wang, and Yan Li Copyright © 2015 Liang Wang et al. All rights reserved. Real-Time Incompressible Fluid Simulation on the GPU Sun, 18 Jan 2015 14:28:22 +0000 We present a parallel framework for simulating incompressible fluids with predictive-corrective incompressible smoothed particle hydrodynamics (PCISPH) on the GPU in real time. To this end, we propose an efficient GPU streaming pipeline to map the entire computational task onto the GPU, fully exploiting the massive computational power of state-of-the-art GPUs. In PCISPH-based simulations, neighbor search is the major performance obstacle because this process is performed several times at each time step. To eliminate this bottleneck, an efficient parallel sorting method for this time-consuming step is introduced. Moreover, we discuss several optimization techniques including using fast on-chip shared memory to avoid global memory bandwidth limitations and thus further improve performance on modern GPU hardware. With our framework, the realism of real-time fluid simulation is significantly improved since our method enforces incompressibility constraint which is typically ignored due to efficiency reason in previous GPU-based SPH methods. The performance results illustrate that our approach can efficiently simulate realistic incompressible fluid in real time and results in a speed-up factor of up to 23 on a high-end NVIDIA GPU in comparison to single-threaded CPU-based implementation. Xiao Nie, Leiting Chen, and Tao Xiang Copyright © 2015 Xiao Nie et al. All rights reserved. Investigating Variations in Gameplay: Cognitive Implications Thu, 15 Jan 2015 13:51:13 +0000 There is increasing interest in creating computer games for learning, problem solving, and other high-level cognitive activities. When investigating whether gameplay is conducive to such activities, gameplay is often studied as a whole. As a result, cognitive implications can be linked to the game but not to its structural elements. Given that gameplay arises from interaction between the player and the game, it is the structural components of interaction that should be investigated to better understand the design of gameplay. Furthermore, minor variations in the components of interaction can have significant cognitive implications. However, such variation has not been studied yet. Thus, to gain a better understanding of how we can study the effect of interaction on the cognitive aspect of gameplay, we conducted an exploratory investigation of two computer games. These games were isomorphic at a deep level and only had one minor difference in the structure of their interaction. Volunteers played these games and discussed the cognitive processes that emerged. In one game, they primarily engaged in planning, but in the other game they primarily engaged in visualizing. This paper discusses the results of our investigation as well as its implications for the design of computer games. Kamran Sedig, Robert Haworth, and Michael Corridore Copyright © 2015 Kamran Sedig et al. All rights reserved. Rigid Body Interaction for Large-Scale Real-Time Water Simulation Sun, 14 Dec 2014 00:10:14 +0000 Simulating large amounts of water in real time is often achieved using heightfield methods. Allowing the water to interact with rigid bodies is essential for applications such as games, but traditional heightfield interaction methods concentrate on water-to-body effects by letting water flow through the bodies. We instead take an approach where the bodies block water. Our earlier method is improved in several ways, taking steps toward a single method to create both water-to-body and body-to-water effects. The new method is also visually compared to a traditional method by Thürey et al. A drawback of our method is that it has some grid aliasing artifacts that appear especially when the method is used for floating bodies. However, our method is demonstrated to work together with the Thürey method, which allows us to get the best of both worlds to simulate both floating and blocking bodies in a single scene. The method runs in real time for large areas of water even with a very limited GPU budget. Timo Kellomäki Copyright © 2014 Timo Kellomäki. All rights reserved. Evaluating Multiple Aspects of Educational Computer Games: Literature Review and Case Study Sun, 07 Dec 2014 14:13:46 +0000 Evaluation is an important step in the life cycle of software, once through this practice it is possible to find issues that could compromise the user experience. With educational computer games, the same rule is applied. The use of educational games is increasing, and it is important to verify these tools to provide users with the most adequate learning environments. This verification can be made through the evaluation of multiple aspects of these tools. This work presents a literature review about evaluation of multiple aspects of software, followed by a more specific review focused on multiple aspects of educational computer games. Then, a case study is presented, in which an evaluation method is applied with an educational computer game, aiming to verify the positives and the issues to be improved in the game. The reviews and the description of the process to use the method intend to help and guide other researchers to choose evaluation methods that can fit their own context and needs. Juvane Nunes Marciano, Leonardo Cunha de Miranda, and Erica Esteves Cunha de Miranda Copyright © 2014 Juvane Nunes Marciano et al. All rights reserved. Interactive Digital Serious Games for the Assessment, Rehabilitation, and Prediction of Dementia Mon, 24 Nov 2014 12:44:01 +0000 Dementia is a serious, progressive, and often debilitating illness with no known cure, having a severe adverse effect on memory, behaviour, reasoning, and communication. A comprehensive review of current refereed research material in the use of games in this area is scarce and suffers from being orientated towards commercially available games or derivatives such as “Dr. Kawashima’s brain training.” There is much lesser concern for bespoke research grade alternatives. This review will attempt to assess the current state of the art in research orientated games for dementia, importantly identifying systems capable of prediction before the onset of the disease. It can be ascertained from the literature reviewed that there are clearly a large number of interactive computer game based mechanisms used for dementia. However, these are each highly intrusive in terms of affecting normal living and the patient is aware of being tested; furthermore their long-term or real benefits are unknown as is their effect over conventional tests. It is important to predict cognitive impairment at a stage early enough to maximise benefit from treatment and therapeutic intervention. Considering the availability, use, and increasing power of modern mobile smartphones, it is logically plausible to explore this platform for dementia healthcare. Sayed Kazmi, Hassan Ugail, Valerie Lesk, and Ian Palmer Copyright © 2014 Sayed Kazmi et al. All rights reserved. An Efficient Sleepy Algorithm for Particle-Based Fluids Wed, 12 Nov 2014 09:46:39 +0000 We present a novel Smoothed Particle Hydrodynamics (SPH) based algorithm for efficiently simulating compressible and weakly compressible particle fluids. Prior particle-based methods simulate all fluid particles; however, in many cases some particles appearing to be at rest can be safely ignored without notably affecting the fluid flow behavior. To identify these particles, a novel sleepy strategy is introduced. By utilizing this strategy, only a portion of the fluid particles requires computational resources; thus an obvious performance gain can be achieved. In addition, in order to resolve unphysical clumping issue due to tensile instability in SPH based methods, a new artificial repulsive force is provided. We demonstrate that our approach can be easily integrated with existing SPH based methods to improve the efficiency without sacrificing visual quality. Xiao Nie, Leiting Chen, and Tao Xiang Copyright © 2014 Xiao Nie et al. All rights reserved. Foggy Scene Rendering Based on Transmission Map Estimation Sun, 19 Oct 2014 00:00:00 +0000 Realistic rendering of foggy scene is important in game development and virtual reality. Traditional methods have many parameters to control or require a long time to compute, and they are usually limited to depicting a homogeneous fog without considering the foggy scene with heterogeneous fog. In this paper, a new rendering method based on transmission map estimation is proposed. We first generate perlin noise image as the density distribution texture of heterogeneous fog. Then we estimate the transmission map using the Markov random field (MRF) model and the bilateral filter. Finally, virtual foggy scene is realistically rendered with the generated perlin noise image and the transmission map according to the atmospheric scattering model. Experimental results show that the rendered results of our approach are quite satisfactory. Fan Guo, Jin Tang, and Xiaoming Xiao Copyright © 2014 Fan Guo et al. All rights reserved. An Overview of Serious Games Wed, 15 Oct 2014 07:55:44 +0000 Serious games are growing rapidly as a gaming industry as well as a field of academic research. There are many surveys in the field of digital serious games; however, most surveys are specific to a particular area such as education or health. So far, there has been little work done to survey digital serious games in general, which is the main goal of this paper. Hence, we discuss relevant work on serious games in different application areas including education, well-being, advertisement, cultural heritage, interpersonal communication, and health care. We also propose a taxonomy for digital serious games, and we suggest a classification of reviewed serious games applications from the literature against the defined taxonomy. Finally, the paper provides guidelines, drawn from the literature, for the design and development of successful serious games, as well as discussing research perspectives in this domain. Fedwa Laamarti, Mohamad Eid, and Abdulmotaleb El Saddik Copyright © 2014 Fedwa Laamarti et al. All rights reserved. A Comprehensive Review of Serious Games in Health Professions Mon, 04 Aug 2014 00:00:00 +0000 Education of healthcare professionals is of primary importance for patient safety. In some health related professions, education and training have to be practiced during the entire working period and not only limited to school years. The use of new technology such as virtual reality and e-learning brings new possibilities with significant improvement in learning outcomes. Serious gaming describes a technology that can educate and train while entertaining users. This type of training can be very useful for health professions because it improves learning outcomes creating a learner oriented approach and providing a stealth mode of teaching. In some fields it represents an ideal instrument for continuous health professions education also in terms of costs because it is cheaper than traditional training methods that use cadavers or mannequins. In this paper we make a scoping review of serious games developed for health professions and health related fields in order to understand if they are useful tools for health related fields training. Many papers confirmed that serious gaming is a useful technology that improves learning and skills development for health professionals. Francesco Ricciardi and Lucio Tommaso De Paolis Copyright © 2014 Francesco Ricciardi and Lucio Tommaso De Paolis. All rights reserved. A Practical Approach for Identity-Embodied 3D Artistic Face Modeling Tue, 24 Jun 2014 08:09:41 +0000 This paper describes a practical technique for 3D artistic face modeling where a human identity can be inserted into a 3D artistic face. This approach can automatically extract the human identity from a 3D human face model and then transfer it to a 3D artistic face model in a controllable manner. Its core idea is to construct a face geometry space and a face texture space based on a precollected 3D face dataset. Then, these spaces are used to extract and blend the face models together based on their facial identities and styles. This approach can enable a novice user to interactively generate various artistic faces quickly using a slider control. Also, it can run in real-time on an off-the-shelf computer without GPU acceleration. This approach can be broadly used in various 3D artistic face modeling applications such as a rapid creation of a cartoon crowd with different cartoon characters. Tanasai Sucontphunt Copyright © 2014 Tanasai Sucontphunt. All rights reserved. A New Methodology of Design and Development of Serious Games Sun, 01 Jun 2014 09:27:32 +0000 The development of a serious game requires perfect knowledge of the learning domain to obtain the desired results. But it is also true that this may not be enough to develop a successful serious game. First of all, the player has to feel that he is playing a game where the learning is only a consequence of the playing actions. Otherwise, the game is viewed as boring and not as a fun activity and engaging. For example, the player can catch some items in the scenario and then separate them according to its type (i.e., recycle them). Thus, the main action for player is catching the items in the scenario where the recycle action is a second action, which is viewed as a consequence of the first action. Sometimes, the game design relies on a detailed approach based on the ideas of the developers because some educational content are difficult to integrate in the games, while maintaining the fun factor in the first place. In this paper we propose a new methodology of design and development of serious games that facilitates the integration of educational contents in the games. Furthermore, we present a serious game, called “Clean World”, created using this new methodology. André F. S. Barbosa, Pedro N. M. Pereira, João A. F. F. Dias, and Frutuoso G. M. Silva Copyright © 2014 André F. S. Barbosa et al. All rights reserved. Unifying Rigid and Soft Bodies Representation: The Sulfur Physics Engine Thu, 29 May 2014 00:00:00 +0000 Video games are (also) real-time interactive graphic simulations: hence, providing a convincing physics simulation for each specific game environment is of paramount importance in the process of achieving a satisfying player experience. While the existing game engines appropriately address many aspects of physics simulation, some others are still in need of improvements. In particular, several specific physics properties of bodies not usually involved in the main game mechanics (e.g., properties useful to represent systems composed by soft bodies), are often poorly rendered by general-purpose engines. This issue may limit game designers when imagining innovative and compelling video games and game mechanics. For this reason, we dug into the problem of appropriately representing soft bodies. Subsequently, we have extended the approach developed for soft bodies to rigid ones, proposing and developing a unified approach in a game engine: Sulfur. To test the engine, we have also designed and developed “Escape from Quaoar,” a prototypal video game whose main game mechanic exploits an elastic rope, and a level editor for the game. Dario Maggiorini, Laura Anna Ripamonti, and Federico Sauro Copyright © 2014 Dario Maggiorini et al. All rights reserved. Dead Reckoning Using Play Patterns in a Simple 2D Multiplayer Online Game Mon, 12 May 2014 08:37:42 +0000 In today’s gaming world, a player expects the same play experience whether playing on a local network or online with many geographically distant players on congested networks. Because of delay and loss, there may be discrepancies in the simulated environment from player to player, likely resulting in incorrect perception of events. It is desirable to develop methods that minimize this problem. Dead reckoning is one such method. Traditional dead reckoning schemes typically predict a player’s position linearly by assuming players move with constant force or velocity. In this paper, we consider team-based 2D online action games. In such games, player movement is rarely linear. Consequently, we implemented such a game to act as a test harness we used to collect a large amount of data from playing sessions involving a large number of experienced players. From analyzing this data, we identified play patterns, which we used to create three dead reckoning algorithms. We then used an extensive set of simulations to compare our algorithms with the IEEE standard dead reckoning algorithm and with the recent “Interest Scheme” algorithm. Our results are promising especially with respect to the average export error and the number of hits. Wei Shi, Jean-Pierre Corriveau, and Jacob Agar Copyright © 2014 Wei Shi et al. All rights reserved. Modeling a Virtual World for the Educational Game Calangos Thu, 24 Apr 2014 08:41:41 +0000 Ecology plays a central role in biology and deserves special attention in scientific education. Nonetheless, the teaching and learning of ecology face a number of difficulties. In order to tackle these difficulties, electronic games have recently been used to mediate ecology learning. This paper presents an electronic game that fulfills these gaps in order to make the students’ work with ecological concepts more concrete, active, and systematic. The paper presents the computational model of the ecological system included in the game, based on a real ecological case, a sand dune ecosystem located in the semiarid Caatinga biome, namely, the sand dunes of the middle São Francisco River, in the state of Bahia, Brazil. It includes various ecological relationships between endemic lizards and the physical environment, preys, predators, cospecifics, and plants. The engine of the game simulates the physical conditions of the ecosystem (dune topography and climate conditions with their circadian and circannual cycles), its biota (plant species and animal species), and ecological relationships (predator-prey encounters, cospecific relationships). We also present results from one classroom study of a teaching sequence structured around Calangos, which showed positive outcomes regarding high school students’ understanding of thermal regulation in ectothermic animals. Angelo C. Loula, Leandro N. de Castro, Antônio L. Apolinário Jr., Pedro L. B. da Rocha, Maria da Conceição L. Carneiro, Vanessa Perpétua G. S. Reis, Ricardo F. Machado, Claudia Sepulveda, and Charbel N. El-Hani Copyright © 2014 Angelo C. Loula et al. All rights reserved. Neural Network to Solve Concave Games Mon, 10 Mar 2014 13:09:28 +0000 The issue on neural network method to solve concave games is concerned. Combined with variational inequality, Ky Fan inequality, and projection equation, concave games are transformed into a neural network model. On the basis of the Lyapunov stable theory, some stability results are also given. Finally, two classic games’ simulation results are given to illustrate the theoretical results. Zixin Liu and Nengfa Wang Copyright © 2014 Zixin Liu and Nengfa Wang. All rights reserved. Analytical Ballistic Trajectories with Approximately Linear Drag Thu, 30 Jan 2014 09:44:39 +0000 This paper introduces a practical analytical approximation of projectile trajectories in 2D and 3D roughly based on a linear drag model and explores a variety of different planning algorithms for these trajectories. Although the trajectories are only approximate, they still capture many of the characteristics of a real projectile in free fall under the influence of an invariant wind, gravitational pull, and terminal velocity, while the required math for these trajectories and planners is still simple enough to efficiently run on almost all modern hardware devices. Together, these properties make the proposed approach particularly useful for real-time applications where accuracy and performance need to be carefully balanced, such as in computer games. Giliam J. P. de Carpentier Copyright © 2014 Giliam J. P. de Carpentier. All rights reserved. Analyzing the Effect of TCP and Server Population on Massively Multiplayer Games Mon, 20 Jan 2014 06:42:53 +0000 Many Massively Multiplayer Online Role-Playing Games (MMORPGs) use TCP flows for communication between the server and the game clients. The utilization of TCP, which was not initially designed for (soft) real-time services, has many implications for the competing traffic flows. In this paper we present a series of studies which explore the competition between MMORPG and other traffic flows. For that aim, we first extend a source-based traffic model, based on player’s activities during the day, to also incorporate the impact of the number of players sharing a server (server population) on network traffic. Based on real traffic traces, we statistically model the influence of the variation of the server’s player population on the network traffic, depending on the action categories (i.e., types of in-game player behaviour). Using the developed traffic model we prove that while server population only modifies specific action categories, this effect is significant enough to be observed on the overall traffic. We find that TCP Vegas is a good option for competing flows in order not to throttle the MMORPG flows and that TCP SACK is more respectful with game flows than other TCP variants, namely, Tahoe, Reno, and New Reno. Other tests show that MMORPG flows do not significantly reduce their sending window size when competing against UDP flows. Additionally, we study the effect of RTT unfairness between MMORPG flows, showing that it is less important than in the case of network-limited TCP flows. Mirko Suznjevic, Jose Saldana, Maja Matijasevic, Julián Fernández-Navajas, and José Ruiz-Mas Copyright © 2014 Mirko Suznjevic et al. All rights reserved. Desirable Elements for a Particle System Interface Sun, 05 Jan 2014 14:37:49 +0000 Particle systems have many applications, with the most popular being to produce special effects in video games and films. To permit particle systems to be created quickly and easily, Particle System Interfaces (PSIs) have been developed. A PSI is a piece of software designed to perform common tasks related to particle systems for clients, while providing them with a set of parameters whose values can be adjusted to create different particle systems. Most PSIs are inflexible, and when clients require functionality that is not supported by the PSI they are using, they are forced to either find another PSI that meets their requirements or, more commonly, create their own particle system or PSI from scratch. This paper presents three original contributions. First, it identifies 18 features that a PSI should provide in order to be capable of creating diverse effects. If these features are implemented in a PSI, clients will be more likely to be able to accomplish all desired effects related to particle systems with one PSI. Secondly, it introduces a novel use of events to determine, at run time, which particle system code to execute in each frame. Thirdly, it describes a software architecture called the Dynamic Particle System Framework (DPSF). Simulation results show that DPSF possesses all 18 desirable features. Daniel Schroeder and Howard J. Hamilton Copyright © 2014 Daniel Schroeder and Howard J. Hamilton. All rights reserved. Procedural Audio in Computer Games Using Motion Controllers: An Evaluation on the Effect and Perception Mon, 23 Dec 2013 11:28:52 +0000 A study has been conducted into whether the use of procedural audio affects players in computer games using motion controllers. It was investigated whether or not (1) players perceive a difference between detailed and interactive procedural audio and prerecorded audio, (2) the use of procedural audio affects their motor-behavior, and (3) procedural audio affects their perception of control. Three experimental surveys were devised, two consisting of game sessions and the third consisting of watching videos of gameplay. A skiing game controlled by a Nintendo Wii balance board and a sword-fighting game controlled by a Wii remote were implemented with two versions of sound, one sample based and the other procedural based. The procedural models were designed using a perceptual approach and by alternative combinations of well-known synthesis techniques. The experimental results showed that, when being actively involved in playing or purely observing a video recording of a game, the majority of participants did not notice any difference in sound. Additionally, it was not possible to show that the use of procedural audio caused any consistent change in the motor behavior. In the skiing experiment, a portion of players perceived the control of the procedural version as being more sensitive. Niels Böttcher, Héctor P. Martínez, and Stefania Serafin Copyright © 2013 Niels Böttcher et al. All rights reserved. Reconstructing 3D Tree Models Using Motion Capture and Particle Flow Thu, 07 Nov 2013 15:41:59 +0000 Recovering tree shape from motion capture data is a first step toward efficient and accurate animation of trees in wind using motion capture data. Existing algorithms for generating models of tree branching structures for image synthesis in computer graphics are not adapted to the unique data set provided by motion capture. We present a method for tree shape reconstruction using particle flow on input data obtained from a passive optical motion capture system. Initial branch tip positions are estimated from averaged and smoothed motion capture data. Branch tips, as particles, are also generated within a bounding space defined by a stack of bounding boxes or a convex hull. The particle flow, starting at branch tips within the bounding volume under forces, creates tree branches. The forces are composed of gravity, internal force, and external force. The resulting shapes are realistic and similar to the original tree crown shape. Several tunable parameters provide control over branch shape and arrangement. Jie Long and Michael D. Jones Copyright © 2013 Jie Long and Michael D. Jones. All rights reserved.