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View Full Version : why a 3D graphics engine



grady
09-03-2000, 08:29 AM
Ok I read the back of Quake 3 or something and it says ACTION PACKED and all this hoobla and NEW GRAPHICS ENGINE THAT MAKES GAMEPLAY....
Well alright you have opengl library and glut and all this stuff (i'm very new to oepngl by the way but i'm posting this in the advanced forum cause it seems advanced to me http://www.opengl.org/discussion_boards/ubb/biggrin.gif) but what exactly does a graphics engine do, I mean how can the "graphics engine" from quake be so different than the "graphics engine" from half-life if they both are made in Opengl? What i'm asking is-what does a "graphics engine" consist of and what is it supposed to do?

skw|d
09-03-2000, 10:38 AM
OpenGL renders what you tell it to. The graphics engine will take a set of data and render it on a screen. Quake3 will take the world data and preprocess it into a BSP tree. When the game is running, it uses this technology to determine which surfaces are potentialy visible and only sends that to the hardware card instead of the entire data set.

Another technology uses "portals" to draw the world from the camera's view frustum which allows for zero overdraw.

The hidden surface removal is probably the main concern for graphics engine designers and its speed defines how much of other features you can add to the engine and still maintain acceptable framerates.

/skw|d

grady
09-03-2000, 11:00 AM
Ok, thanks. What is a BSP tree by the way? http://www.opengl.org/discussion_boards/ubb/biggrin.gif

DJ Tricky S
09-03-2000, 01:46 PM
BSP = Binary Space Partition

grady
09-04-2000, 06:40 PM
Ok were can i learn more about what a binary space partition is?? http://www.opengl.org/discussion_boards/ubb/confused.gif

skw|d
09-05-2000, 09:58 PM
BSPs are used by many, but the newer technology is portal rendering. You might get more out of your time if you research that. The BSP concept goes back to the 80s and many of the new engines in production are using portals.

/skw|d