Caelum Graphics System (CGS), Pre-Release Development Version (unnumbered)

// PURPOSE AND GENERAL USAGE =====================================================

CGS is a minimalist C++ wrapper for modern OpenGL (4.x). It is built around making
the sort of operations many graphics APIs (such as Ogre3D) treat as "advanced"
functionality core to its usage. This makes CGS far more efficient and powerful
than most graphical APIs, at the cost of a higher learning curve.

Examples of CGS' power-user functionality include:
* The ability to directly read and write to textures through a simplified
interface with minimal overhead
* GLSL shaders are integral to CGS' operation; there is no fixed function
* Shader programs have per-mesh state (this can however introduce some overhead 
and will be enhanced in the future to be less wasteful)
* Vertex attributes and their types are entirely defined by the user

#NOTE# CGS currently lacks what is usually considered a core component of graphics
APIs: a scene graph. As a result, it is not possible to handle transforms, moving,
sorting, clipping, and various other operations automatically. This effectively
limits CGS to 2D rendering, very controlled 3D, GUIs, fractals, and several other
applications that don't depend highly on 3D space positioning of objects. A scene
graph is planned in the near future, and the render queue is designed with
implementing one in mind.

I plan to port CGS to Vulkan in the near future. There should be minimal API
changes in this shift, as CGS was already built with an external interface
designed to be friendly to Vulkan (or similar).

CGS is not now and probably will not be thread-safe. It is possible it will be
made so during the Vulkan shift, but I am skeptical how useful a multi-threaded
graphics API really is. You can, of course, use CGS in a multi-threaded project
as long as you only access CGS (and OpenGL, if you make external calls) with one
thread. This is indeed the expected usage.

// BUILDING ======================================================================

CGS can be built either directly into your program or as a library. In either
case, it has the following dependencies:
* OpenGL 4.1+ hardware and drivers
* GLEW and GLUT (eg, freeglut)
* SDL2
* FreeImage

If building on Windows, it is strongly suggested you obtain these via MSYS2:
< http://msys2.github.io/ >. OpenGL will be provided by your video drivers
(AMD, Nvidia, Intel, etc.), so ensure those are up to date.

CGS is only officially supported for GCC compilers. It may, however, work for any
other with the proper configuration. C++11 support is required.

== Build into Project ==
The suggested way (currently) to use CGS is to build it directly into your project
(game/product/whatever). To do this:

1. Add CGS's sources (src) and headers (inc) to your build
2. Add the path to CGS' dependencies to your link search paths
3. Add CGS's dependencies to your link
(On Windows + MSYS2, these are: "glew32 glu32 opengl32 SDL2main SDL2 freeimage".
Bote that the "32" is there even if you are using mingw64 via MSYS2. Control
32 bit vs 64 bit via the search path.)
4. Build your project normally

== Build as Library ==

1. Update the provided CMakeLists.txt:
- With your system include and library paths to where the dependencies reside
(System_Include_Path and System_Library_Path)
- With any platform-specifc compiler flags
("-mwin32" is REQUIRED for MSYS2)
- Adjust Special_CXX_Flags to your liking
2. Run cmake and build CGS
(With MSYS2, use: 'cmake -G "MSYS Makefiles"')
3. Link CGS to your program as you would any other library. You may also need
to link your program directly to GLEW and GLUT for some functionality currently.
4. Ensure you place the CGS library somewhere your program will find it at
runtime. On Windows, the best place is usually the same directory as the EXE.

Currently supported/tested systems:
* Windows 7 64 bit
* ...

// CONTACT =======================================================================

Official Repo: https://github.com/WilliamKappler/caelumGraphicsSystem
(This is subject to change in the near future)
Documentation Wiki: http://onathacar.fredlawl.com/

Please email me if you have any questions, concerns, requests, or contributions
at < [email protected] >.

// LICENSE =======================================================================

CGS is licensed under the extremely permissive ISC license, which is essentially
a less wordy MIT license. See LICENSE for the proper project-wide license terms.
Note, however, that some CGS dependencies might have different licenses.

How to handle the location of the license notice for MIT/BSD-like licenses is
often a point of confusion. I will say I am not particularly concerned with how
or where you include it, nor is any particular location required by the license,
but I suggest one of the following:

* The credits scroll (games)
* A document distributed with your program (README, manual, etc.)
* The "about" dialog/page
* A "licenses" or such console command (CLI programs especially)
* Included CGS sources

Because the wording of the license might be confusing if merely included on its
own (it might imply your program is distributed under it as well), I suggest
prefixing CGS's ISC license for clairity. For example:

This program uses the Caelum Graphics System, distributed under the ISC license:
	Copyright (c) 2015-2016, William Kappler

	Permission to use, copy, modify, and/or distribute this software for any
	purpose with or without fee is hereby granted, provided that the above
	copyright notice and this permission notice appear in all copies.

	THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
	WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
	MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
	ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
	WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
	ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
	OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

The above likely holds for other MIT/BSD like licenses, but do not consider this
legal advice.