Engines

[Nick]

This sounds quite amateur of a question, but what is a graphics engine, specifically? I understand that it contains functions for drawing and using models but why use that and not something like OpenGL? Also, what differentiates a Game Engine from a Graphics Engine? I'm just trying to learn my way up to actually making games, so any advice is appreciated.

[Carlos Camacho]

3D Engine
A set of code that creates graphics that looks 3D. An engine would have all the necessary components from loading the models and data to drawing them on the screen.

Game Engine
A program code that runs all aspects of the game.


OpenGL
A graphics API, primarily used for 3D, created by Silicon Graphics which runs on most platform OSes. The prime competitor is Direct3D.

OpenGL vs. rolling your own 3D Engine
Benefit = Hard work is done by OpenGL.org, tons of tutorials, hardware accelleration support by OS and video card

Why make your own?
Your needs are very specific, you're a 3D whiz like John Carmack, it interests you
(many books and texts on creating your own 3D engine on the Internet)

Note, there are also 3rd party/independent 3D engines, such as Torque, Crystal Space Engine. See this list http://cg.cs.tu-berlin.de/~ki/engines.html

Moderators are free to edit my post for corrections. :)

[arekkusu]

OpenGL is lower level than an engine. All it knows about is drawing points, lines, and polygons, optionally with some fancy effects like lighting, texturing, and fog.

That's really about all it does. It doesn't know how to draw windows, or spheres, or models, or worlds, or anything like that.

Some of the very common functions, like drawing a sphere, or opening a window, are provided in standard libraries (GLU, GLUT) along with OpenGL. But anything higher, like loading a map, or animating a character model, you have to write an engine for.

[Josh]

Also, what differentiates a Game Engine from a Graphics Engine?The answers will probably vary a tad, but in my way of thinking the difference is that the graphics engine will drive just that -- the graphics. The game engine, on the other hand, will take care of things such as windows, events, preferences, etc.

[Nick]

Thanks for all the responses.