The tremendous advantageous 3D video games have over 2D video games is the ability of moving objects to interact in three dimensions with other elements in the scene. Pre-rendered textures, in contrast, are essentially 2D images that are warped or wrapped onto 3D surfaces but still remain two-dimensional. One analogy that is apt for at least some applications is to think of a texture as being like a complex photograph pasted onto a billboard. From a distance, the photograph can look extremely realistic. However, if you walk up and touch the billboard you will immediately find out that the image is only two dimensional and cannot be interacted with in three dimensions.
We have discovered a unique way to solve this problem in the context of real-time interactive video game play. Just as Alice was able to travel into a 3D world behind her mirror in the story "Alice Through the Looking Glass", we have developed a video game play technique that allows rich pre-rendered images to create 3D worlds with depth.
In one embodiment, we use a known technique called cube mapping to pre-render images defining a 3D scene. Cube mapping is a form of environment mapping that has been used in the past to provide realistic reflection mapping independent of viewpoint. For example, one common usage of environment mapping is to add realistic reflections to a 3D-rendered scene. Imagine a mirror hanging on the wall. The mirror reflects the scene in the room. As the viewer moves about the room, his or her viewpoint changes so that different objects in the room become visible in the mirror. Cube mapping has been used in the past or provide these and other reflection effects.
We use cube mapping for a somewhat different purpose--to pre-render a three-dimensional scene or universe such as for example a landscape, the interior of a great cathedral, a castle, or any other desired realistic or fantastic scene. We then add depth to the pre-rendered scene by creating and supplying a depth buffer for each cube-mapped image. The depth buffer defines depths of different objects depicted in the cube map. Using the depth buffer in combination with the cube map allows moving objects to interact with the cube-mapped image in complex, three-dimensional ways. For example, depending upon the effect desired, moving objects can obstruct or be obstructed by some but not other elements depicted in the cube map and/or collide with such elements. The resulting depth information supplied to a panoramically-composited cube map provides a complex interactive visual scene with a degree of 3D realism and interactivity not previously available in conventional strictly 2D texture mapped games.
No, I hope something like this fits better.
