Ray Casting is a technique used to draw a 3D world using "rays" of light originating from the viewer (or more correctly, a view plane). By solving a linear equation, it can be determined if a ray intersects with a surface or not, and if so, where in 3D space the intersection occurs.

The technique is in many ways similar to Ray Tracing. The most notable difference is that with Ray Casting the rays are never reflected off the objects they hit, nor will anything cast shadows (although the latter can be simulated by using pre-rendered texture maps). Also, while a ray can theorhetically intersect with any kind of surface, most Ray Casting engines limit themselves to polygons or triangles to keep rendering times low.

Another advantage Ray Casting has over traditional polygon rendering is that there is no need to calculate hidden surfaces, or to keep a Z buffer. Nor is it required to scale or rotate textures beforehand, as the solution to the mentioned "ray equation" give the final coordinates for the texture.

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