**1. Introduction**

282 Petri Nets – Manufacturing and Computer Science

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**6. References** 

Systems", V – 1.0

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No. 3, pp. 36-46, 2008

Computer, 1982

Thesis, NTNU, Norway, 2011

2011

Interactive Storytelling is one of most promising technologies for the development of new media and new forms of digital entertainment. Interactive Storytelling can be defined as the endeavour to develop new media in which the presentation of a narrative, and its evolution can be influenced, in real-time, by the user. In traditional forms of storytelling, a storyteller would present the scenario of a story to the audiences in a predefined way (also known as a plot), which limited the variation in character interactions and context. The story refers to the succession of actions that happen in the world represented by the narrative. The origin of computerized storytellers can be traced to the "story-generation system TALE-SPIN" (Meehan, J., 1981) which is the most popular generator of short tales. A scene of the storyline is composed of beats, where the term beat refers to the smallest unit of action that has its own complete shape. A beat is a dramatic action that occurs in a scene to achieve a narrative goal. It consists of


The growing interest in Interactive Storytelling as a Research topic and as a potential technology derives from the current competition between traditional and interactive digital media. Interactive Storytelling is of interest to broadcasters and computer game producers alike. In the former case, Interactive Storytelling will bring interactivity into traditional media, potentially revolutionizing the entertainment experience. In the latter, it would improve the narrative and "aesthetic" value of computer games, with the potential to develop new game genres and attract a wider audience. The term Interactive Storytelling is sometimes used in a broader sense in the field of new media, to reflect the fact that some

interactive systems, like computer games, can be designed to reflect an underlying narrative, which is conveyed via the gameplay, often enhanced by animation cut scenes.

State of the Art in Interactive Storytelling Technology: An Approach Based on Petri Nets 285

Story plot and character(s) are the two most important element of a story. As a consequence, several approaches, at different levels of complexity, have been developed for representing plots in games, monitoring the course of the story and controlling stories in games and

iv. Petri nets (PN) (Delmas, G. et. al, 2007; Brom, C. & Abonyi, A. 2006; Karam, H., 2010).

Several years of research are establishing Petri nets (PN) and its extension High-level PN as a process modelling formalism for a variety of application domains, for instance: network protocols, logistics, scientific workflows and gaming theory. Their power lies in their formal semantics and non semantics properties. The main contribution of this chapter is to show how workflow management concepts can be jointly utilized with Petri nets (PN) for modeling game systems and game workflow control. This is done by composing the game rules in the game's workflow environment by different triggers and effects. The idea is derived from the study of PN, game theory, workflow management, story writting, AI, and cinematography in interactive storytelling. In this contribution, interactive storytelling is viewed as a hybrid form of game design and cinematic storytelling for entertainment applications among two skills: artistic and technical. Evaluation and performance results in terms of some case study called crazy ball 2 are also demonstrated. Crazy ball 2 is a platform-type genre, much like the worldwide-known game Mario and the Konami's

Recently, interactive storytelling has become a major issue in video games development. Several categories of video games arose to either historical, editorial or narrative criteria. Within the field of Interactive Storytelling, interactive drama is a computer-based fiction where a user chooses most of the actions for the main character in a story. Interactive drama is the ultimate challenge of digital entertainment because it involves both the dynamic generation of narrative events and the integration of user inputs within the generation. This is a hard challenge, because it involves both the dynamic generation of narrative events and the integration of user inputs within the generation. Moreover, both Storytelling unfolding and player's interaction can't take place at the same time. The first relates to game designer's control of the game he/she has created as the second relates to player's control on the game he/she has bought. Each interactive drama needs a model of narrative. The challenge of interactive drama is to find a model suited to the interactive nature of computers. Interactive drama architecture has several key components: the environment, the player, the user, the writer, and the director. For successful interactive drama architecture, three requirements

storytelling applications. These techniques are summarized as follows:

i. Planning techniques (Riedl, M. & Stern, A., 2006);

iii. Finite-state machines (Sheldon, L., 2004), and

ii. Beat approach (Brom, et. al., 2007);

**2.2. Problem statement and objectives** 

are necessary (Magerko, B. & Laird, J. 2003):

Castlevania series.

iii. Computer game design, and iv. Artificial intelligence.

On the other hand, several years of research are establishing Petri nets (PN) (Tado, M., 1990; Peterson, J. L., 1997) and its extension High-level PN as a process modelling formalism for a variety of application domains. A high level PN is a Petri net extended with colour, time, and hierarchy (Jenson, K., 1997). The power of Petri nets lies in its formal semantics and non semantics properties. This chapter addresses a new application domain of PN for modeling game systems and game workflow control in the context of workflow management concept and game rules principles. It presents state-of-the-art results with respect to interactive storytelling and PN, and highlights some petri-net-based workflow tools for game design. This is done by proposing an integrated framework for deeply combining interactivity and narrative in computer games which is achieved by:


Evaluation and performance results supported by some case study called crazy ball 2 are also demonstrated. Crazy ball 2 is a platform-type genre, much like the worldwide-known game Mario and the Konami's Castlevania series.

In the reminder of this chapter we will offer insights into how workflow management concepts can be jointly utilized with Petri nets (PN) for modeling game systems and game workflow control. To do this, we first introduces the problem statatment, prior research and objectives in section 2. Section 3, briefly summarizes the background and the basic terminology and notions that will be used throughout this chapter. Section 4 introduces the methodology used. Evaluation and practical performance results are discussed in Section 5. Sections 6 concludes this chapter and outlines some directions for future work.
