# Adobe Acrobat’s Overlooked JavaScript Capability Used to Run Doom in PDFs
In the realm of technology and gaming, there’s a rich legacy of stretching the limits of software and hardware capabilities. From executing *Doom* on calculators to refrigerators, hackers and fans have continually discovered inventive methods to introduce the legendary 1993 first-person shooter to unusual devices. The newest chapter in this illustrious saga? *Doom* operating within a PDF file.
Indeed, you read that right. Thanks to the work of developer Ading2210, you can now engage in *Doom* within the confines of a PDF document. This whimsical undertaking utilizes Adobe Acrobat’s lesser-known JavaScript functionality, a capability that has been available for decades yet is seldom employed for anything beyond mere interactivity in forms. Here’s a glimpse into how this captivating achievement was realized and its significance.
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## **The Unseen Potential of JavaScript in PDFs**
Adobe’s PDF format is widely recognized for its ability to maintain document layout across various devices and platforms. Nonetheless, many individuals are unaware that Adobe Acrobat has supported JavaScript since the early 2000s. This feature was originally created to enable dynamic components, such as form validations, calculations, and interactive buttons, within PDF files.
Although this JavaScript functionality is comprehensive, it has mostly been neglected for more imaginative uses. Recently, hackers have begun probing its potential, programming simple games like *Breakout* and *Tetris* into PDFs. Ading2210, however, has taken this experimentation to extraordinary heights by integrating *Doom* into a PDF document.
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## **The Inner Workings: A Technical Overview**
Ading2210’s endeavor exemplifies the creativity of the coding community. Here’s a detailed rundown of how *Doom* was brought to existence in a PDF:
1. **Utilizing Open Source Code**: The project kicked off with a streamlined variant of *Doom*’s open-source code, specifically the *doomgeneric* project. This rendition of *Doom* is engineered to operate on minimal systems, making it an excellent choice for unconventional devices.
2. **Recompiling with Emscripten**: By employing an older version of Emscripten, a toolchain for converting C and C++ code into JavaScript, Ading2210 transformed the *Doom* code into optimized asm.js. This enabled the game to function within the JavaScript environment available in PDFs.
3. **Simulating Video Output**: Given that PDFs are not tailored for real-time graphics, the project employs a clever workaround. The game’s video output is translated into ASCII text and displayed across 200 individual text fields, with each representing a horizontal segment of the *Doom* display. This constructs a six-color monochrome representation of the game at a playable 13 frames per second.
4. **Managing Input**: Gamers interact with the experience by typing commands into a designated text field. While this mode of input is less than ideal—rendering simultaneous actions like moving and shooting nearly unfeasible—it suffices for basic gameplay.
5. **Functionality in Chromium Browsers**: The project depends on PDFium, the PDF rendering engine utilized in Chromium-based browsers like Google Chrome and Microsoft Edge. While the PDF does not function in desktop versions of Adobe Acrobat, it operates seamlessly in these modern browsers.
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## **Constraints and Hurdles**
Even though the concept of playing *Doom* in a PDF is undoubtedly intriguing, the execution carries several constraints:
– **Input Limitations**: The dependence on text-field input renders gameplay cumbersome, as players are unable to execute multiple actions simultaneously.
– **Performance**: At 13 frames per second, the experience is playable but far from fluid. The ASCII-based visualization also restricts graphical clarity.
– **Compatibility**: The PDF fails to function in standalone versions of Adobe Acrobat, limiting its accessibility to Chromium-based browsers.
Despite these limitations, the project serves as an impressive showcase of what can be achieved with a touch of ingenuity and technical expertise.
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## **The Significance of This Development**
The *Doom*-in-a-PDF initiative is more than just an entertaining experiment—it underscores the unexplored possibilities of existing technologies. Adobe’s JavaScript functionality in PDFs, originally aimed at mundane activities such as form validation, has been creatively repurposed to accomplish something genuinely surprising. This highlights that even the most disregarded features can be utilized in innovative manners.
From a security standpoint, the project also emphasizes the need to comprehend and manage the capabilities of software. JavaScript in PDFs has long been a conduit for vulnerabilities, and initiatives like this reveal just how potent (and potentially hazardous) this feature can be.
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## **The Potential of PDF Gaming Moving Forward**
While engaging in *Doom* within a PDF may not supplant your gaming PC anytime soon, it paves the way for fresh opportunities. Could we witness more games adapted to PDFs? Perhaps even interactive educational resources or simulations?
