REVISIONS AND ADDITIONS TO DIGITAL DAGUERREOTYPES VERSION 1.1 4 September 1992 This release of the Digital Daguerreotypes prologue, DIGIDA.INI or DIGIDA.PS, includes the following revisions and additions: REVISIONS --------- LIMITCHECK ERROR SOLVED. Certain procedures in Version 1.0 invoking the strokepath operator resulted in a limitcheck error when run on Adobe PostScript Level 1 devices; Version 1.1 resolves this problem by calling an explicit flattenpath before the strokepath to reduce the level of path complexity. POSTSCRIPT LEVEL 2 COMPATIBILITY FOR HALFTONE SCREENS. As Adobe Systems has documented, typical PostScript Level 1 routines for determining the current halftone screen spot function and then invoking this spot function as a parameter for the setscreen operator may provoke a typecheck error on PostScript Level 2 devices. Version 1.1 uses a new ChooseSpot procedure compatible with PostScript Level 1 and PostScript Level 2 devices alike. MORE CONVENIENT TREATMENT OF RBEZIER PROCEDURE. The RBezier procedure has been enhanced to permit the convenient drawing of closed paths combining lineto and rcurveto elements (e.g. a representation of the spine of a book), and an RBezierP procedure added for defining one or more rcurveto segments as part of a path where the currentpoint is already defined. TREATMENT OF CTM BY SBLEND PROCEDURE. The SBlend procedure now optionally concludes with the current transformation matrix (CTM) set to its state at the end of the procedure, but with the gray level restored to its state at the start of the procedure. CORRECTION OF UNMATCHED GSAVE IN POLYLATHE PROCEDURE. An unbalanced GS (gsave) operator has been corrected; the new code restores the gray level and linewidth values to their settings at the start of the procedure. ADDITIONS --------- NEW EQUILATERAL TRIANGLE PROCEDURE. A convenience operator Equilateral has been added for the drawing of equilateral triangles. PROTOTYPE 3-D COORDINATE SYSTEM. With release 1.1, Digital Daguerreotypes incorporates a true three-dimensional world coordinate system, including procedures for 3-D scaling, translation, rotation, or shearing; and one-point, two-point, or three-point perspectives. Sample artwork files demonstrate some true 3-D techniques, including Interior Surface Management (ISM), which permits showing exterior and exposed interior surfaces of a cube or other object with separate definitions for rendering the exterior and interior surfaces of a given facet of the object. --------------------------------------------- For more information, please see PROTO3D.TXT. --------------------------------------------- ************************ NEW ARTWORK (.EPD) FILES Version 1.01 includes 22 new artwork files, some demonstrating the new 3-D coordinate system in applications such as imaging a cube with Interior Surface Management (ISM), and generating a shaded surface plot of a two-variable function. The files ADMIRAL.EPD and SPCUGLGO.EPD, while designed using the standard PostScript coordinate system as opposed to "true 3-D," may be of interest both as illustrations of complex designs, and as "benchmarks" for various PostScript language implementations. M. P. S.