Computer Graphics Programming

TO COMPUTER GRAPHICS BASED ONGKS Part I gives an introduction to basic concepts of computer graph­ ics and to the principles and concepts of GKS. The aims of this part are twofold: to provide the beginner with an overview of the terminology and concepts of computer graphics, based on GKS, and to give the computer graphics expert an introduc­ tion to the GKS standard. In the early chapters of this part, the main areas of computer graphics, the various classes of com­ puter graphics users, the interfaces of GKS and its underlying design concepts are discussed and important terms are defined. The later chapters give an informal introduction to the main concepts of GKS and their interrelationships: output, attributes, coordinate systems, transformations, input, segments, metafile, state lists, and error handling. This introduction to the GKS framework will prepare the ground for the detailed description of 2D GKS functions in Part III and the 3D extensions to GKS in Part IV. 1 WHAT IS COMPUTER GRAPHICS? 1. 1 Defmition of Computer Graphics The Data Processing Vocabulary of the International Organization for Stan­ dardization (ISO) [ISO 84] defines Computer Graphics as follows: "Methods and techniques for converting data to and from a graphic display via computer. " This definition refers to three basic components of any computer graphics system - namely "data", "computer", and "display".

Contenu

I - Introduction to Computer Graphics Based on GKS.- What Is Computer Graphics?.- 1.1 Definition of Computer Graphics.- 1.2 Areas of Computer Graphics.- 1.3 Impact of the Graphical Kernel System on Computer Graphics.- 2 Aims and Contents of Part I.- 3 The Computer Graphics User.- 4 Interfaces of the Graphical Kernel System.- 5 Principles and Goals of the Graphical Kernel System.- 6 Main Concepts of the Graphical Kernel System.- 7 Creating Graphical Output.- 7.1 Line Graphics and Raster Graphics.- 7.2 Output Primitives and Attributes.- 7.2.1 Output Primitives.- 7.2.2 Output Primitive Attributes.- 7.3 Indices, Bundles, and Tables.- 8 Coordinate Systems and Transformations.- 8.1 Coordinate Systems.- 8.2 Transformations.- 8.3 The Normalization Transformation.- 8.4 Clipping.- 9 The Graphical Workstation.- 9.1 Routing Output to Workstations.- 9.2 Types of GKS Workstations.- 9.3 The Workstation Transformation.- 9.4 The Deferral State.- 9.5 Addressing Special Workstation Capabilities.- 10 Input.- 10.1 Interactive Computer Graphics.- 10.2 Logical Input Device Classes.- 10.3 Operating Modes.- 10.4 Echoes, Prompts, and Input Device Initialisation.- 11 Segments.- 11.1 Structuring Pictures.- 11.2 Manipulating Segments.- 11.3 Segment Attributes.- 11.4 Segment Transformations.- 11.5 Workstation-Dependent and Workstation-Independent Segment Storage.- 11.6 Copying Segments.- 12 The GKS Metafile.- 12.1 Graphics Metafiles.- 12.2 GKSM and CGM.- 12.3 The Metafile Interface.- 12.4 The Metafile Formats.- 13 States and State Lists.- 13.1 The GKS Operating State.- 13.2 The State Lists.- 13.3 Inquiry Functions for State List Values.- 14 Error Handling.- 15 3D Extensions to GKS.- II - The Process of Generating a Standard.- 1 The Evolution of Computer Graphics.- 1.1 Graphical Devices.- 1.2 Graphics Software.- 1.3 SEILLAC I.- 2 Committees, People, and Events.- 2.1 Graphics Standardization Committees.- 2.2 People.- 2.3 Overview of the Main Events.- 3 GKS Review - Problems and Their Solutions.- 3.1 Scope of the Standard.- 3.2 Output Primitives.- 3.3 Segmentation.- 3.4 Input.- 3.5 Transformations.- 3.6 Workstation Concept.- III - Graphical Kernel System Programming.- 1 Format and Structure of Part III.- 1.1 Contents of Part III.- 1.2 Format of GKS Function Definitions.- 1.2.1 Example of the Definition of GKS Functions.- 1.2.2 Format of Language-Independent Definition.- 1.2.3 Format of FORTRAN Definition.- 1.3 Format of Examples.- 1.3.1 Example of an Example.- 1.3.2 Format of Pascal Examples.- 1.3.3 Format of FORTRAN Examples.- 1.4 Exercises.- 2 Levels.- 2.1 Overview.- 2.2 Functionality of the GKS Levels.- 2.2.1 The Minimal or Lowest Level of GKS (Level 0 a).- 2.2.2 Level 0 b.- 2.2.3 Level 0c.- 2.2.4 Levels 1a, 1b, 1c.- 2.2.5 Levels 2a, 2b, 2c.- 2.3 The Impact on Writing Portable Application Programs.- 2.4 Exercises.- 3 States and State Lists.- 3.1 Introduction.- 3.2 Operating States.- 3.3 The Functions Allowed in Individual States.- 3.4 State Lists.- 3.5 Basic Control Functions.- 3.6 Examples.- 4 Workstations.- 4.1 Introduction.- 4.2 Workstation Description Table.- 4.3 Workstation State List.- 4.4 GKS Functions Which Involve Workstations.- 4.5 Workstation Control.- 4.6 Deferring Picture Changes.- 4.7 Addressing Workstation Capabilities Not Covered by GKS.- 4.8 Examples.- 4.9 Exercises.- 5 Transformations.- 5.1 Coordinate Systems.- 5.2 Normalization Transformation.- 5.3 Workstation Transformation.- 5.4 Clipping.- 5.5 Transformation of LOCATOR and STROKE Input.- 5.6 Examples.- 5.7 Exercises.- 6 Output Primitives.- 6.1 Introduction.- 6.2 POLYLINE Primitive.- 6.2.1 Global POLYLINE Attributes.- 6.2.2 Workstation-Dependent POLYLINE Attributes.- 6.3 POLYMARKER Primitive.- 6.3.1 Global Polymarker Attributes.- 6.3.2 Workstation-Dependent POLYMARKER Attributes.- 6.4 TEXT Primitive.- 6.4.1 TEXT Attributes for Beginners.- 6.4.2 Character Body.- 6.4.3 Text Extent Rectangle.- 6.4.4 Text Font and Precision.- 6.4.5 Setting Global Text Attributes.- 6.4.6 Workstation-Dependent TEXT Attributes.- 6.5 FILL AREA Primitive.- 6.5.1 Global FILL AREA Attributes.- 6.5.2 Workstation-Dependent FILL AREA Attributes.- 6.6 CELL ARRAY Primitive.- 6.7 Generalized Drawing Primitive (GDP).- 6.8 Attribute Setting Functions Which Concern All Primitives.- 6.8.1 Setting the Colour Table.- 6.8.2 Setting the Aspect Source Flags.- 6.8.3 Setting the Pick Identifier.- 6.8.4 Clipping Rectangle.- 6.9 Examples.- 6.10 Exercises.- 7 Segments.- 7.1 Introduction.- 7.2 How Are Segments Generated?.- 7.3 What Is Stored in a Segment?.- 7.4 When Are Primitives Taken from the Transformation Pipeline?.- 7.5 Segment Creation and Deletion.- 7.6 Manipulation of the Segment Attributes.- 7.7 The Workstation-Independent Segment Storage (WISS).- 7.8 Different Levels of Segmentation.- 7.9 Utility Functions.- 7.10 Examples.- 7.11 Exercises.- 8 Input.- 8.1 Introduction to Logical Input Devices.- 8.1.1 Identification.- 8.1.2 Logical Input Classes and Values.- 8.1.3 Operating Modes.- 8.1.4 Logical Input Device Model.- 8.1.5 Setting the Logical Input Device Mode.- 8.2 Details About Logical Input Devices.- 8.2.1 LOCATOR and STROKE Devices.- 8.2.2 Valuator.- 8.2.3 Choice.- 8.2.4 Pick.- 8.2.5 String.- 8.3 Initialising Logical Input Devices.- 8.4 Changing the Input Device Mode.- 8.5 Request Input.- 8.6 Sample Input Functions.- 8.7 Event Input.- 8.7.1 Input Queue and Current Event Report.- 8.7.2 Functions to Await and Delete Event Queue Entries.- 8.7.3 Get Input Functions.- 8.8 A Compound Example of Using the GKS Input Functions.- 8.9 Exercises.- 9 Error Handling.- 9.1 Strategy.- 9.2 The Emergency Closure Procedure.- 9.3 The ERROR HANDLING and ERROR LOGGING Procedures.- 9.4 Error Detection Within GKS Procedures.- 9.5 Reaction of Application Programs to Error Detections.- 9.6 List of GKS Error Numbers and Messages.- 9.6.1 States.- 9.6.2 Workstations.- 9.6.3 Transformations.- 9.6.4 Output Attributes.- 9.6.5 Output Primitives.- 9.6.6 Segments.- 9.6.7 Input.- 9.6.8 Metafiles.- 9.6.9 Escape.- 9.6.10 Miscellaneous Errors.- 9.6.11 System Errors.- 9.6.12 Reserved Errors.- 9.6.13 Implementation-Dependent Errors.- 9.7 Exercises.- 10 Inquiry Functions.- 10.1 State Lists and Inquiry Functions.- 10.1.1 Error Reports in Inquiry Functions.- 10.1.2 Inquiry Functions for the Settable State Lists.- 10.1.3 Inquiry Functions for the Workstation Description Table.- 10.1.4 Inquiry Functions for the Error State List and Pixel Memories.- 10.2 Description of the Inquiry Functions.- 10.2.1 Inquiry Function for Operating State.- 10.2.2 Inquiry Functions for GKS Description Table.- …