APLBAGS(ID:5648/apl010)

Graphical extensions to APL 

Graphical extensions to APL
Related languages
APL => APLBAGS   Extension of
References:
  • Bassman, M.J., "APLBAGS - An APL Basic Graphics Subroutine Package for Tektronix 4013 Storage Tube Terminal," Computer Graphics, Vol. 7, No. 4, 1973. view details Extract: Introduction
    INTRODUCTION
    This paper describes APLBAGS (pronounced "apple bags") -- a software package by means of which an APL programmer can produce graphics output for and receive input from a Tektronix 4013 Storage Tube Terminal. The introduction contains a brief description of the 4013 and describes the goals of the designer of the package. Section 2 (user's Manual) explains how an APL programmer can use the package to build and modify pictures. Section 3 (Package Logic) briefly describes how the package works.

    The Tektronix ,013 has two operating modes. In Graphic Plot mode the 4013 uses 1,024 addressable points along the x-axis and y-axis. Only 781 points (0 through 780) are visible in the y direction. In Alpha mode the coordinates x=0, y=767 are called Home position, the lower left corner of the first character position in the upper left corner of the screen. DOI
  • Neal, M. Catherine and Shapiro, Linda G. "A Portable Graphics system for minicomputers" pp704-712 view details Extract: Description
    Historically SKETCHPAD (Sutherland) was the first widely recognized general purpose graphics system. The SKETCHPAD system consists of a collection of subroutines called interactively through a menu selection process. The system allows pictures to be constructed hierarchically from other pictures and is noted for its use of a ring data structure to store picture descriptions. Kulsrud, Williams, and Giloi presented models for the definition of a general purpose graphics language, Kulsrud suggested that the first version of the proposed language have written commands and that it later be adjusted to accept input from graphics devices such as light pens and trackballs. The language she described was capable of picture description, manipulation, and analysis. Although it could be used with interactive applications programs, it was not an interactive language. Williams described a language that provided (i) data types with related operations particularly suited to graphical applications, and (2) the ability to add new data types and operations. For example, a "point,' could be a data type, and a specially defined addition operator would operate on that data type. The language was thus highly extensible, but it was not interactive. Giloi proposed a model to be used in constructing either subroutine packages for graphic display applications or graphical extensions to existing  languages. In this model, pictures were described as a hierarchy of subpictures and picture primitives. Primitives were defined as anything for which there was a hardware generator in the display processor, placing limits on the device independence  of a language developed from his model. An interactive version of the model was developed by extending APL to include graphics capabilities, and a non-interactive version was developed as a FORTRAN subroutine package.

    The general purpose graphics systems presented in recent years can be classified as (i) subroutine packages for graphics applications, (2) graphics extensions to existing languages, and (3) new languages possessing graphics capabilities. Graphics subroutine packages are most widely distributed particularly by manufacturers of graphics display hardware. Some example packages are GINO-F, GPGS, GRAF, DISSPLA, and EXPLOR. Most packages are limited to the manipulation of picture displays with few programming control or storage capabilities. Where such abilities are available they often serve specialized purposes as in WAVE, a package for waveform analysis. One exception is the VIP system where the user is able to combine the available system function subroutines into special purpose functions which can then be used in the same way that the original system functions were used.

    Extensions of an existing language such as Euler-G, IMAGE, APLBAGS, APLG, and PENCIL, provide a programmer with graphics capabilities as well as general programming features. Euler-G has excellent data structure definition facilities. IMAGE, an extension of FORTRAN, cannot  provide the data structure description capabilities  that are available in Euler-G, but it has the advantage of being based on the most widely distributed host language available. APLBAGS, APLG, and PENCIL, an extension of the MULTILANG on-line programming system, are truly conversational languages. GRASP, a PL/I extension, is a compiled language but it allows dynamic interaction. GRASP also allows the definition of models from which complex pictures can be created hierarchically. ESP3, an extension of SNOBOL4, is a non-interactive language  from which many of the high-level concepts found in PIGLI are drawn. Language extensions are found mainly in experimental installations. Two complete graphics languages are METAVISU and GLIDE. Both take characteristics from a base language (PL/I and ALGOL, respectively) and add capabilities for defining, displaying, and manipulating pictures. Full languages are less widely distributed than subroutine packages or language extensions.


          in Proceedings of the 1978 annual conference 1978, Washington, D.C., United States view details