Interactive music composition through computer graphics.

Software development for both compositional systems and computer graphics has been extensive in the computer music field. Compositional systems employ different techniques in supporting the global strategies of composers, and they require alphanumeric input. Programs in computer graphics have been concerned primarily with the representation of common music notation. A System for Interactive Music Composition Through Computer Graphics was developed to provide a composer with an interactive, compositional, graphics environment.Musical constructs are not depicted in the system through common music notation, but through line-segment graphs. Since music is a temporal art, any musical parameter can be represented as a function of time. The process of visually/aurally perceiving structure is enhanced by using graphs instead of strings or tables of numbers as traditionally used in computer music. There are also no notational restrictions on frequency and rhythm like those encountered with common music notation. The system provides a way for the composer to organize the large amount of data needed in computer music composition.There are visual transformations in computer graphics which correlate to aural transformations in music. Algorithms for translation, scaling, and rotation support the musical transformations of transposition, augmentation, diminution, inversion, retrograde, and retrograde-inversion. The windowing algorithm is used throughout the system for inserting and extracting structures. This algorithm is also used in editing a portion of a structure in which that section is displayed on the graph for a finer level of detail. Structures can be created through entering points interactively, generating transformations of an existing structure, realizing a statistical distribution, or extracting a section from an existing structure. Editing possibilities include inserting or deleting points, lines, and curves, inserting one structure within another, or generating transformations of one structure within each line segment of another. These options help make the system both efficient and flexible.When the composer becomes familiar with the system, a large amount of data can be generated in a short time. It is a very powerful tool for organizing and manipulating musical constructs. The system can be used with relative ease by beginning as well as advanced composers.Thesis (D.A.