An ruby-processing extension for scripting storyboarded explanatory visualizations. In progress.
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README.rdoc

Storyboard

Storyboard is an animation language, for creating mathematical explanatory narratives – movies that display a sequence of display objects, intended to illustrate or explicate different aspects of an underlying model or idea, in an order that the author designs when she creates the animation.

The emphasis of Storyboard is on explanatory visualizations, mostly in two dimensions. (Storyboard is intended to work with a variety of back-end rendering systems, but Storyboard itself makes no specific contribution to 3-dimensional rendering or animation.) Storyboard is not intended as a framework for the well-served aspect of character animation.

Furthermore, Storyboard is intended for animations that contain a sequence of scenes or panels, where each panel contains different elements and different labels. It is not intended as a replacement for the many capable systems that display, or allow the user to interact with, the visual display of a single model or set of models using a single technique.

The goal of Storyboard is that a reasonably industrious programmer, who is able to envision an animated visual explanation for a mathematical concept, should be able to create a fluid, attractive movie that demonstrates this concept. Furthermore, the work that goes into creating this movie should also be useful in creating cartoons, interactive applications, or illustrations for a web page or academic paper.

Specifically, the author has had several such ideas for visual explanations, and found himself unable to communicate these because of the difficulty of finding an existing animation system that was targeted towards this specific domain. The first use of Storyboard will be to realize these explanations.

Some longer-term goals include the exploration of the relationships between mathematical explanations and more conventional forms of narrative, of relationships between pedagogical animations and dramatic sequences, and the use of concepts, such as split-screen and montage, from the vocabulary of film. Concepts such as unity of time and space, the relationship between visual shots and narrative beats, and the introduction of display objects (or characters) that are then cut away from to build suspense, will be explored from the top down (by building in system-level constructs that represent these concepts) and from the bottom up (by using system-provided abstractions to build and explore them).

Overview

Storyboard is a text-based language. It is largely declarative, and, as such, could be used as the basis for a graphical animation construction tool, but it is designed as an authoring language, and to be human-readable. It is intended to embody the concepts and abstractions that make the creation of animations directly tractable, independently of the use of tools other than a text editor.

Key Concepts

The key concepts in Storyboard are the display object, the stage, and the panel. These describe, respectively, the what, the where, and the when.

A display object is an object that knows how to draw itself. Storyboard provides a set of basic display objects that correspond to 2D primitives, and to objects (such as callouts) from the vocabulary of illustration. Any particular implementation of Storyboard will additional binds against a graphics API (such as Processing, OpenGL, MathPlotLib, or Vtk) that can be used to create additional display objects.

A stage is a partition of space into different blocks, to which different display objects or categories of objects can be assigned. Just as a panel partitions a storyboard by time, a stage partitions the spatial extent of the display area into blocks.

A panel represents the display state during a period of time (its “duration”). A panel encapsulates a set of display objects that are drawn during a particular portion of the animation, and describes the way that these objects change during the duration of the panel.

The storyboard is a collection of panels, display objects, and stages; together with metadata (the script's title, author, date). The storyboard corresponds to the document in a document-based system such as a text editor or word processor (although a single storyboard may consist of multiple files).

Additional Concepts

Each panel has an optional caption, that narrates the information that the panel displays. The caption can be displayed on the screen, or collected into a narration script.

A scene is a sequence of panels. The scene is convenience for organizing large storyboards. The names and descriptions of scenes can also be used as an index for rendering part of a storyboard, and in the construction of a table of contents for a movie or comic.

An animation variable (or “avar”) is a variable whose value changes continuously as a function of time, or of other variables. Animation variables are used “under the hood” in order to resize, or reposition objects. They are also exposed as a tool for code that defines more complex effects as a function of time.

Animation variables can be eased.

A display object may be derived from a model, which is a description only of a set of values related to or derived from an object, not how they are described. The derivation may be implemented by writing code, or defining equations that relate the display properties of the display object to the values of the model. Several display objects may display the same model at the same or different times.

Output Formats

A storyboard can be displayed as:

A movie is a non-interactive linear display of the frames of the storyboard, that is intended for continuous display from beginning to end (although the viewer may pause and resume it, or play only a portion). Each panel is generally rendered into a sequence of frames; these are appended to each other in the same order as the panels are ordered within the storyboard.

The scene descriptions and panel captions can be composited onto the frames, or exported as a separate script for a narrator to read as a voiceover.

The display can also incorporate the names of scenes, and their relative position within the script, or order to orient the viewer within the logical structure of the movie.

The meta-information within the screenplay may be used to provide start or end titles or credits.

An applet is an interactive presentation of the information in the storyboard. In addition to the properties of a movie, it might provide user interface elements to navigate between the scenes in non-linear order, to manipulate the camera position and field of view independently from the specifications in the storyboard, and to manipulate the positions of display objects or the values of models.

An image set is a set of images, one for each of the storyboard's panels or scenes. The images are intended for use in a web page or an article. They are dumped into a directory, whence they can be included into a LaTeX or other document.

A cartoon is a set of images that are layed out within a page, and annotated with scene descriptions and panel captions. A cartoon is similar to an image set, except that it also includes the document that includes (and lays out) the images.

API

Storyboard is implemented as a set of definitions within the Ruby programming language. The current implementation of Storyboard uses the Processing library as a display back end (and therefore requires Ruby-Processing).

The storyboard keyword defines a storyboard. There should be only one of these. storyboard accepts a block. Within the block, code can use the size, background, frame_rate, author, title, date keywords, and can make other Processing calls (such as color_mode).

A display object is an instance of any Ruby class that implements a draw method. draw uses the functions of the Processing library.

The panel keyword defines a panel. panel takes a block argument, whose contents , and add display objects to the stage (via stage).

Within a panel definition, the caption and duration keywords define the panel caption and duration, respectively. The duration is in seconds, and defaults to 1s if it is not otherwise specified.

An object that is created within a panel is drawn within all subsequent panels within the same scene, until a panel calls the unstage or clear_stage function. unstage function removes its argument or arguments from the stage. clear_stage removes all display objects from the stage.

Status

So far, I'm developing this solely to support a personal project (visualizing the geometry of the Discrete Fourier Transform). There aren't enough examples, and it isn't yet baked.

Storyboard metadata is not implemented. Movie creation is not integrated into the framework. See the TODO file for a longer list of known omissions.