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YetAnotherGameEngineQuestion

Started by Tha_Kurious_One Aug 6, 2003 at 12:00 PM 7 replies 1k views

Original Post

Aug 6, 2003 at 12:00 PM

I know that a game engine basically loads stuff from disk and passes it to some api like OpenGL to render a scene. But what i really want to know is how much work does the engine do and what is left to the api. Take the case of rendering a scene. If an api like OpenGL has all the functions to do the actual rendering then what part does the engine code play? The way i see it, the engine is just good enough to load stuff and feed it to the api. Then why call it engine ? wouldn''t "Loader" or "Feeder" be good enough ? Please clear this whole Engine deal for me.

Sneftel

Aug 6, 2003 at 12:19 PM

OpenGL is a graphics API, not a scene management API. All it can do, basically, is draw triangles where you tell it to draw triangles. Also, keep in mind that a game is more than graphics; there''s sound, input, networking, etc. to consider.

From your post, it''s clear that you''re not really familiar with OpenGL. I suggest you take some time to learn its capabilities; that will probably best answer your questions.

How appropriate. You fight like a cow.

JTippetts

Aug 6, 2003 at 2:34 PM

OpenGL has no idea what a rocket is. Or a bullet. Or an armored marine. Or even a vicious, vermicious knid. The engine stands as a layer between OpenGL, which can in the end draw the polygons and fragments of said knid, and the user. The engine knows what a knid is (or at least understands the underlying attributes of a knid; the actual knid might be implemented in game content which is operated upon by the engine). Tell OpenGL to draw your knid, and it will laugh derisively at you. Tell your engine to draw a knid, and it will patiently hold OpenGL''s hand and guide it through the process, minus the mocking laughter.

There is a great deal more going on in a true engine than just loading a bunch of data and dumping it to OpenGL.

Note that there are a lot of projects out there that would pass themselves off as engines, when in truth they should much rather be called tech demos or some such. They, in truth, merely load data and feed it to OpenGL. I rather like your "Feeder" terminology in describing these.

Josh
vertexnormal AT email DOT com

Check out Golem at:
My cheapass website

Sneftel

Aug 6, 2003 at 2:43 PM

quote:
Original post by VertexNormal
Or even a vicious, vermicious knid.

I believe you''re forgetting the ARB_VERMICIOUS_KNID extension that''s going into OGL 1.5.

How appropriate. You fight like a cow.

Xsist10

Aug 6, 2003 at 5:33 PM

a graphics engine takes on the role of data management (textures / models / meshes / levels) and the system of choosing what to render to the scene (BSP / Portal / ROAM / etc). While it doesn''t seem much, it is a large part of the game programming

Radagar

Aug 7, 2003 at 9:06 AM

Just wanted to say GREAT reply VertexNormal.

~~~~~~~~~~~
Chris Vogel
~~~~~~~~~~~

superpig

Aug 7, 2003 at 10:01 AM

quote:
Original post by VertexNormal
OpenGL has no idea what a rocket is. Or a bullet. Or an armored marine. Or even a vicious, vermicious knid. The engine stands as a layer between OpenGL, which can in the end draw the polygons and fragments of said knid, and the user. The engine knows what a knid is (or at least understands the underlying attributes of a knid; the actual knid might be implemented in game content which is operated upon by the engine). Tell OpenGL to draw your knid, and it will laugh derisively at you. Tell your engine to draw a knid, and it will patiently hold OpenGL''s hand and guide it through the process, minus the mocking laughter.

Ah, but IIRC vermicious knids can change shape (that''s how they did the letters in the elevators, remember), so they could just turn into triangles and then OpenGL would know how to render them... no engine required

Superpig
- saving pigs from untimely fates, and when he''s not doing that, runs The Binary Refinery.
Enginuity1 | Enginuity2 | Enginuity3 | Enginuity4

JTippetts

Aug 11, 2003 at 9:35 AM

quote:
Original post by superpig

Ah, but IIRC vermicious knids can change shape (that''s how they did the letters in the elevators, remember), so they could just turn into triangles and then OpenGL would know how to render them... no engine required

Yes, you must be wary of those rotten knids. Change into triangles, they may, but trust them, I do not. They might decide instead to change into a trojan. Then, of course, you are left with the question of what to do about the awful Wangdoodles, and the Snozzwangers, and even the Hornswogglers, if you are so inclined to include them.

Josh
vertexnormal AT email DOT com

Check out Golem at:
My cheapass website

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