Topic: What exactly IS a game engine?

[mouse_clicker]

I didn't know where else you post this, and I figured the guys who frequent this board might be able to tell me. I always hear developers and people talk about game engines, but I don't know what they actually are. I'm guessing it involves with the way you play the games, but I don't know anything beyond that, or even if that's right. Can anyone help me?

[DRJ]

The engine can be defined as all the non-game specific technology. Think of a game engine like a car engine. The engine makes the car go, but doesnt tell you anything about what the car looks like. In fact you can use the same engine with many different car models that are all competely different. Now if you want the car to do more than it can with its specific engine, you would need a new engine.

So for example you can have a game engine for a FTS like doom or unreal and use it to make many different games with different artwork, computer AI, animation etc.

Or lets say Nintendo took the Zelda WW engine and changed all the characters and weapons, scenery to make a completely different (non-zelda) game. It would still be using the same engine, but would be completely different.

Hope that made sence.

[joeamis]

Now if you want the car to do more than it can with its specific engine, you would need a new engine.

everything he said was true, but i'd like to add that if you want a car to do more than it can with it's specific engine you can change things and upgrade it, and the same goes for videogame engines.
the most memorable story i remember is when Nintendo decided to use the Mario 64 engine for Mario Kart 64, so they optimized it...improved the draw distance, etc.

lots of times developers use the same engine for different games because it takes alot less time and $ to create the game when they don't have to create an entire new engine.
the developers of downhill domination used the same engine they had used for twisted metal black.

often when a game engine is so good, you will have complete seperate companies pay to use that same engine to make their games!  often it's a very hefty price tag.  

[mouse_clicker]

Thanks a lot guys. I've got a LOT better idea of what a game engine is. I thought the term engine was more of a figurative term and that it could be compared to a car engine so well. Thanks again.

[PIAC]

i had no idea the mario 64 engine powered mario kart (pun not intended)

some examples you  could use to see different uses for the same engine would be the Quake 3 engine, it powers Medal of Honour and Jedi Knight Outcast, if you look at those two games and at quake 3, you will see similarities, as, obviously, its the same engine.

[ThePerm]

Simply put it is a computer program.

Why do they call it an engine. Well put it this way. Every computer program in the end is exactly the same. It does some calculations and gives output. Much like a car you do certain modifications to this idea and the engine runs differntly- thats why they call it an engine.

heres soem other terms

main engine - this may or not be a game itself, it may just be the menu that gets you into playign the game. Or it runs all the other programs or subroutines.

graphics engine - this is a program(or subroutine) that does all those cool calculations and does all the bells in whistles that you see on screen.

physics engine - this does all thsoe realworld calculations like collsion detection and graviyty, etc

gameplay engine - this is a program that you interact with and accordingly it interacts with the graphics, sounds and physics engines.

sound engine - need i say?

[RockmanX]

Half-Life is built off of the origional Quake engine.

[kennyb27]

Ah, this reminds me, the great folks over at Factor5 decided to scrap the entire game engine from Rogue Squadron II (which pushed 15 million polygons per second) and in it's place create an entire new one which will come near 22 mps.  You gotta' love their desire.

[Raijin Z]

http://tenebrae.sourceforge.net/

Need I say more?

[KDR_11k]

The engine is the interface between the game logic and the hardware (often there's still an API like OpenGL or DirectX between engine and hardware, but we'll ignore that for now). The Hardware gives the engine the user's input, the engine then formats it and forwards it to the game logic. The game logic then interprets the input (e.g. stick up -> walk forward) and tells the engine the result ("Entity 0 just moved forward .25 units and changed it's animation to walk0, frame 1.7") The Engine then determines what that means (i.e. which polygons belong to said entity, how frame 1.7 looks and so on) and forwards that to the hardware ("Okay, draw a poly there, there, there and there, add lights there and there, etc."). Of course, this is a highly simplified version of the processes that are involved in the hardware and software and often parts are mixed and intertwined (e.g. does the engine or game logic handle particles?). If you need it in more detail, ask around on gamedev.net.