Regal

https://github.com/p3/regal

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Contents

• Regal
  • Summary
  • Goals
  • Deployment
  • Features
    • Emulation
    • OpenGL error checking
    • Logging
    • Multi-threading support
    • Spoofing OpenGL vendor, renderer, version and extension strings
    • Browser-based interface
    • Regal OpenGL extensions
  • Regal API
  • In Progress
  • Planned Features
  • Limitations
  • Other Information
  • Platform Notes
    • Windows
    • Linux
    • OS X
    • Android
    • iOS
    • PPAPI and NaCl
  • Questions and Answers
    • STL, Standard C++ Library, Boost
    • Alternatives for OpenGL Loading
    • Related Efforts
  • License and Credits

Summary

OpenGL portability layer for OpenGL 2.x, 3.x, 4.x, Core contexts and ES 2.0

Warning

Regal is pre-alpha software, it is available here for evaluation and to play with the examples. Don't use it in your projects yet. You have been warned.

Goals

Regal is a portable OpenGL layer on top of existing OpenGL implementations. Compile and link an app against Regal and deploy on various OpenGL implementations including compatibility, core and ES 2.0 OpenGL contexts.

• Portability

  Consistent OpenGL API that runs on all major platforms: Windows, Linux, Mac, iOS, and Android

• Compatible

  Immediate mode, fixed function, GL_QUADS work everywhere, emulated as necessary.

• Modern OpenGL API

  Direct State Access (DSA) and Vertex Array Object (VAO), emulated as necessary.

• Open Source

  There is nothing behind the curtain. You can see what Regal is doing and change it if needed.

• Ease of Use

  Set breakpoints on OpenGL functions. Step into the code. Inspect state.

• Efficiency

  If it cannot be implemented efficiently in Regal, it is not universally supported. For example, tessellation support requires tessellation hardware.

Deployment

• Most code remains unchanged.
• Optionally #include <GL/Regal.h>
• Link with regal32.dll, libRegal.so or libRegal.dylib

From an application developer's perspective, Regal just looks like an OpenGL implementation. You link with it instead of your platform's OpenGL library or framework, and that's really all you have to do to use Regal. The rest of your code can remain unchanged.

Features

Emulation

• Fixed function texturing, lighting and fog.

• Direct State Access extension

  http://www.opengl.org/registry/specs/EXT/direct_state_access.txt

• GL_EXT_debug_marker extension

  http://www.khronos.org/registry/gles/extensions/EXT/EXT_debug_marker.txt

• Fixed function and DSA emulation enabled by default, except when compatibility context with DSA extension detected.

• Build-time configuration:

  • REGAL_EMULATION -- Enable/disable the use of emulation
  • REGAL_FORCE_EMULATION -- Force the use of emulation, even for compatibility contexts with DSA

• Environment variable configuration:

  • REGAL_EMULATION -- Enable/disable the use of emulation
  • REGAL_FORCE_EMULATION -- Force the use of emulation, even for compatibility contexts with DSA

• Runime configuration via GL_REGAL_enable:

  • GL_EMULATION_REGAL -- glEnable/glDisable emulation

OpenGL error checking

• Disabled by default.
• Build-time configuration: REGAL_ERROR
• Environment variable configuration: REGAL_ERROR
• Runtime configuration via GL_REGAL_enable: GL_ERROR_REGAL

Logging

Regal supports detailed logging for development purposes.

• Error -- Fatal and non-fatal Regal runtime errors.
• Warning -- Non-fatal Regal warnings.
• Info -- Informational messages.
• App -- Application calls into Regal.
• Driver -- Regal calls into OpenGL.
• Internal -- Internal Regal calls.
• Http -- HTTP traffic logging.

Build-time configuration:

• REGAL_LOG_ERROR
• REGAL_LOG_WARNING
• REGAL_LOG_INFO
• REGAL_LOG_APP
• REGAL_LOG_DRIVER
• REGAL_LOG_INTERNAL
• REGAL_LOG_HTTP

• Debug mode: All logging supported with error, warning, info and http logging enabled.
• Release mode: Support for application, driver and internal logging disabled by default.

Environment variable configuration:

• REGAL_LOG_ERROR
• REGAL_LOG_WARNING
• REGAL_LOG_INFO
• REGAL_LOG_APP
• REGAL_LOG_DRIVER
• REGAL_LOG_INTERNAL
• REGAL_LOG_HTTP
• REGAL_LOG_API --- Application + Driver OpenGL logging
• REGAL_LOG_NONE --- enable or disable all logging

Environment variable lookup is globally disabled by defining REGAL_NO_GETENV at compile-time.

Runtime configuration via GL_REGAL_log extension: (glEnable/glDisable/glIsEnabled)

• GL_LOG_ERROR_REGAL
• GL_LOG_WARNING_REGAL
• GL_LOG_INFO_REGAL
• GL_LOG_APP_REGAL
• GL_LOG_DRIVER_REGAL
• GL_LOG_INTERNAL_REGAL
• GL_LOG_HTTP_REGAL

Other compile-time or runtime configuration of logging:

• REGAL_LOG --- enable or disable logging
• REGAL_LOG_FILE --- log to specified filename
• REGAL_LOG_MAX_LINES --- limit the number of lines of multi-line messages (shaders, etc)
• REGAL_LOG_JSON --- log in JSON mode
• REGAL_LOG_JSON_FILE --- JSON log to specified filename

Multi-threading support

• Enabled by default.
• Build-time configuration: REGAL_NO_TLS

Spoofing OpenGL vendor, renderer, version and extension strings

Build-time configuration

• REGAL_GL_VENDOR
• REGAL_GL_RENDERER
• REGAL_GL_VERSION
• REGAL_GL_EXTENSIONS

Environment variable configuration:

• REGAL_GL_VENDOR
• REGAL_GL_RENDERER
• REGAL_GL_VERSION
• REGAL_GL_EXTENSIONS

Environment variable lookup is globally disabled by defining REGAL_NO_GETENV at compile-time.

Browser-based interface

• Enabled by default.
• REGAL_NO_HTTP --- Build-time and environment variable enable/disable.
• REGAL_HTTP_PORT --- Port for HTTP connections (8080 by default)
• REGAL_HTTP_LOG_LIMIT --- Number of lines of logging buffered
• http://127.0.0.1:8080/log --- View log
• http://127.0.0.1:8080/glEnable?GL_LOG_APP_REGAL --- Enable/disable application logging
• http://127.0.0.1:8080/glEnable?GL_LOG_DRIVER_REGAL --- Enable/disable driver logging
• http://127.0.0.1:8080 --- State information

Regal OpenGL extensions

• GL_REGAL_error_string for GLU-style GLenum to error string conversion.
• GL_REGAL_extension_query for GLEW-style extension checking.
• GL_REGAL_log for Regal logging configuration.
• GL_REGAL_enable for Regal feature configuration.

Regal API

• RegalSetErrorCallback --- Optionally set the per-context error callback function.
• RegalShareContext --- OpenGL contexts are shared.
• RegalMakeCurrent --- Set an OpenGL context as current for the thread.
• RegalDestroyContext --- Cleanup Regal context resources.

In Progress

• Context sharing support
• Pointer-based API
• glPushAttrib emulation

Planned Features

• Debug label.
• Debug output.
• Web browser-based debugging tools.
• Display list emulation.

Limitations

• Incomplete implementation, so far.
• Shared OpenGL contexts supported for single-threaded only.
• Limited GLSL language support.
• GL_QUADS only works in immediate mode or with DrawArrays for ES and core profiles.

Other Information

• #AltDevBlogADay blog: Bringing Regal OpenGL to Native Client.
• opengl.org forum thread: Introducing Regal.
• Slides - Regal for Software Development.

Platform Notes

Windows

Linux

• RedHat/Fedora recommended packages:

• 32-bit:

$ sudo yum install zlib-devel libpng-devel

• 64-bit

$ sudo yum install zlib-devel.i686 libpng-devel.i686 $ sudo yum install zlib-devel.x86_64 libpng-devel.x86_64

• Ubuntu/Debian/Mint recommended packages:

$ apt-get install libxmu-dev libxi-dev

• Use GNU make with Makefile

$ make -f Makefile CCACHE=ccache STRIP=

• Set LD_LIBRARY_PATH

$ export LD_LIBRARY_PATH=`pwd`/lib

• Run the dreamtorus example

$ REGAL_FORCE_EMULATION=1; bin/dreamtorus

$ REGAL_FORCE_EMULATION=0; bin/dreamtorus

$ REGAL_LOG_DRIVER=1; bin/dreamtorus

OS X

Android

iOS

PPAPI and NaCl

Questions and Answers

STL, Standard C++ Library, Boost

• For and against STL.
• For and against Boost.

Alternatives for OpenGL Loading

• GLEW.
• OpenGL Loader Generator.

Related Efforts

• Mesa3D mail thread: Mesa as part of OpenGL-on-OpenGL ES 2.0

License and Credits

Regal code, API database and generators are BSD licensed.

Copyright (c) 2011-2012 NVIDIA Corporation
Copyright (c) 2011-2012 Cass Everitt
Copyright (c) 2012 Scott Nations
Copyright (c) 2012 Mathias Schott
Copyright (c) 2012 Nigel Stewart
All rights reserved.

Redistribution and use in source and binary forms, with or without modification,
are permitted provided that the following conditions are met:

  Redistributions of source code must retain the above copyright notice, this
  list of conditions and the following disclaimer.

  Redistributions in binary form must reproduce the above copyright notice,
  this list of conditions and the following disclaimer in the documentation
  and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
OF THE POSSIBILITY OF SUCH DAMAGE.

Boost is licensed under Boost Software License.

zlib by Jean-loup Gailly and Mark Adler is licensed under zLib License.

libpng by Glenn Randers-Pehrson et. al. is licensed under libpng license.

lookup3 by Bob Jenkins is public domain.

GLEW is licensed under BSD and MIT License.

GLU is licensed under SGI FREE SOFTWARE LICENSE B.

GLUT license:

/* Copyright (c) Mark J. Kilgard, 1994, 1995, 1996, 1998. */

/* This program is freely distributable without licensing fees  and is
   provided without guarantee or warrantee expressed or  implied. This
   program is -not- in the public domain. */

Dreamtorus example program is public domain.