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Wilmington, North Carolina once had a thriving Black middle class and an elected interracial government. In 1898 white supremacists used violence to overthrow that government, kill Black residents and drive many others from the city.
MORE →Reflects the personal views, recollections, and perspective of the author, Mike Davis.
This is a personal recollection on the Move fire on May 13, 1985
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OpenGL Performer, formerly known as IRIS Performer and commonly referred to simply as Performer, is an application development environment.[1][2] It is a commercial library of utility code[3] built on top of OpenGL for the purpose of enabling hard real-time visual simulation applications. OpenGL Performer was developed by SGI. OpenGL Performer is available for IRIX, Linux, and several versions of Microsoft Windows. Both ANSI C and C++ bindings are available.
Performer came about in 1991 when a group from SGI's Open Inventor project, then known as IRIS Inventor, decided to focus on performance rather than ease of programmability. Whereas Inventor delivered easy-to-use objects and various UI elements to interact with them, Performer focused on a scene graph system that could be re-arranged on the fly for performance reasons, allowing the various passes of a rendering task to be performed in parallel in multiple threads. Performer allowed the scene to describe levels of detail with hysteresis bands and fade capabilities. Frame rate and statistics were monitored and a 'stress' factor was calculated. This could be used to further weight the level of detail in the scene eliminating detail to maintain a target frame rate.
Other key features of Performer were the use of symmetric multi-processing capabilities, support multiple graphics pipes and the ability to utilize the scalable resources of high end systems. In this regard Performer was actually simple to use given the underlying complexity. Application culling and rendering could be running in different threads locked to different physical processors. In a multi-pipe (multiple graphics subsystems) configuration rendering to each graphics pipe would have a dedicated thread and similarly culling would also have a dedicated processor. Advanced features like database paging, texture paging and point light source management (for flight simulation) and intersection testing for collision detection would also have dedicated processors allowing asynchronous I/O and processing to occur without negatively impacting graphics performance. Most of this complexity was hidden beneath a simpler scene graph API with relatively high level configuration calls which could be made to set up the threads and inter-process communication.
Performer did not have a native file format, merely plugin loaders from 3rd parties such as MultiGen's OpenFlight format loader. Similarly there was no default runtime, there was sample code and the often used and often modified 'perfly' sample application. This probably contributed to its reputation for being difficult to use.
By the mid-1990s it started to become clear that there was no reason that Inventor and Performer could not be combined. This led to the Cosmo 3D project that SGI was intending to build both Inventor and Performer (now essentially API shims) out of, as well as promote as a new and higher-level standardized API for future work on the SGI platform. However, after the first beta release of Cosmo 3D, SGI joined with Intel and IBM (and later DEC) to create OpenGL++, essentially a cleaned up version of Cosmo. This project died when SGI turned their attention to an almost identical project with Microsoft known as Fahrenheit, which was also killed. Today Inventor and Performer remain separate products, and none of the combined versions ever saw the light of day.
Performer consists primarily of two libraries: the lower-level libpr and the higher-level libpf. The libpr library provides an object-oriented interface to high-speed rendering functions based on the concept of a pfGeoSet and a pfGeoState. A pfGeoSet is a collection of graphics primitives, such as polygons or lines. A pfGeoState encapsulates properties pertaining to a given pfGeoSet such as lighting, transparency, and texturing.
The libpf library includes functions for the generation and manipulation of hierarchical scene graphs, scene processing (simulation, intersection, culling, and drawing tasks), level-of-detail management, asynchronous database paging, dynamic coordinate systems, environment models, light points, and so on. This library also provides transparent support for multiple viewports spread across multiple graphics pipelines.
Other Performer libraries--libpfutil, libpfdb, libpfui, etc.--provide functions for generating optimized geometry, database conversion, device input (such as for interfacing with external flyboxes and MIL-STD-1553 mux busses), motion models, collision models, and a format-independent database interface that supports common data formats such as Open Inventor, OpenFlight, Designer's Workbench, Medit, and Wavefront .obj file.
Source: Wikipedia. Article content is retrieved live through the MediaWiki API.
OpenGL Performer, formerly known as IRIS Performer and commonly referred to simply as Performer, is an application development environment. It is a commercial library of utility code built on top of OpenGL for the purpose of enabling hard real-time visual simulation applications. OpenGL Performer was developed by SGI. OpenGL Performer is available for IRIX, Linux, and several versions of Microsoft Windows. Both ANSI C and C++ bindings are available.
Open Inventor, originally IRIS Inventor, is a C++ object-oriented retained mode 3D graphics toolkit designed by SGI to provide a higher layer of programming for OpenGL. Its main goals are better programmer convenience and efficiency. Open Inventor exists as both proprietary software and free and open-source software, subject to the requirements of the GNU Lesser General Public License (LGPL), version 2.1. The primary objective was to make 3D programming accessible by introducing an object-oriented API, allowing developers to create complex scenes without the intricacies of low-level OpenGL. The toolkit incorporated features like scene graphs, pre-defined shapes, and automatic occlusion culling to streamline scene management. While Open Inventor focused on ease of use, the OpenGL Performer project, spawned from the same context, emphasized performance optimization. The two projects later converged in an attempt to strike a balance between accessibility and performance, culminating in initiatives like Cosmo 3D and OpenGL++. These projects underwent various stages of development and refinement, contributing to the evolution of 3D graphics programming paradigms.
OpenGL (Open Graphics Library) is a cross-language, cross-platform application programming interface (API) for rendering 2D and 3D vector graphics. The API is typically used to interact with a graphics processing unit (GPU), to achieve hardware-accelerated rendering. Silicon Graphics, Inc. (SGI) began developing OpenGL in 1991 and released it on June 30, 1992. It is used for a variety of applications, including computer-aided design (CAD), video games, scientific visualization, virtual reality, and flight simulation. Since 2006, OpenGL has been managed by the non-profit technology consortium Khronos Group.
OpenGL++ was a graphics library written in C++ that supported object-oriented data structures on top of the OpenGL 3D graphics system. The project started as the result of a partnership between SGI, IBM and Intel, and later, Digital Equipment Corporation. It was intended to provide a higher level API than the "bare metal" support of OpenGL, as well as being an implementation for Java3D. Work on OpenGL++ ended when SGI decided to partner with Microsoft instead, leading to the Fahrenheit project, which also died.
Before the 1921 destruction of Tulsa’s Greenwood District, Black residents had created a remarkable center of business and community life. The district included stores, professional offices, entertainment venues and homes owned by Black citizens. Understanding Greenwood means learning what was built—not only what was burned.
MORE →The Greenwood District.