In optics, a caustic is the envelope of light rays reflected or refracted by a curved surface or object, or the projection of that envelope of rays on another surface. The caustic is a curve or surface to which each of the light rays is tangent, defining a boundary of an envelope of rays as a curve of concentrated light.
A piece of milled plexiglass acting as a projecting lens; via the Computer Graphics and Geometry Lab at the École Polytechnique Fédérale de Lausanne
New milling techniques applied to glass and plexiglass panels could be used to “create windows that are also cryptic projectors, summoning ghostly images from sunlight.”
[Pauly and Bompas] hope that the technique will be used in architectural design, to create windows that mould sunlight and throw images or patterns onto walls or floors,” which, if timed, milled, and manipulated just right, could produce a slowly animated sequence of images being projected by an otherwise empty window during different times of day.
To control the shape of a caustic pattern generated by a specular or refractive surface, we need to solve the inverse problem: how can we change the surface geometry, such that incident light is redirected to produce a desired caustic image?
You might think that Mario 64 was built with tickets and sprints, but, according to interviews, there was no master plan, only the principles that the game should feel good and be fun. They started with just Mario in a small room, and tuned his animations and physics until he felt nice and responsive. After that, the levels were also created as they went, with the designers, developers, and director going back and forth using sketches and prototypes.
Building like this is never a straight line. Ideas and code get left on the cutting room floor because part of innovation is questioning whether what you made should exist. The process is cyclical and iterative, looking something like this.