EDSS is a system that allows you to display 2-dimensional sprites in the 3D world in the way used in some oldschool FPS games.
The creators of the first computer games implemented in 3D technology, encountered many problems related to the efficiency of the equipment at the time. The mere rendering of the three-dimensional world of the game absorbed most of the computing power of the computer without leaving it much for the rest of the calculations. Therefore, to display characters and other models, it was decided to use the so-called sprites (ghosts) or two-dimensional images representing a given character or model. It was so-called 2.5D characters.
The character's animation took place through a fast, continuous replacement of the images of a given sprite. For the character, eight separate animations were prepared - one for each of the eight different directions in which the character could be oriented. All pictures for a given character or game model (all animations) were stored in one texture - so-called atlas. The clever system of calculating the image number allowed to display the picture appropriate for a given frame of animation and the angle resulting from the direction of camera observation and the direction in which the given model was returned.
It should be noted that due to the high demand for images, some of the animations of a given character were prepared only as 1-directional. During such animation, the given actor was always facing the camera, no matter what position in the world and what direction the camera had. With this animation, it was not possible to look at the given character from the side or from the back. EDSS supports both: 8- and 1-directional animations as well as 1-frame model positions without any animation.