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?
The text 'added' and 'removed' drifts upwards from the toggle button and fades away.
So we all know Super Mario, right? And if you think about when you’re collecting coins in Super Mario, it doesn’t stop the game and pop up an alert dialogue and say, “You have just collected ten points, OK, Cancel”, right? It just does it. It does it in the background, but it does provide you with a feedback mechanism.
The feedback you get in Super Mario is about the number of points you’ve just gained. When you collect an item that gives you more points, the number of points you’ve gained appears where the item was …and then drifts upwards as it disappears. It’s unobtrusive enough that it won’t distract you from the gameplay you’re concentrating on but it gives you the reassurance that, yes, you have just gained points.