Laser Graffiti — draw on walls with a laser pointer

Point a projector and a webcam at any wall. Draw with a laser pointer. The projector paints your strokes — glowing neon, dripping ink, spinning in 3D. Your browser doesn't support embedded video — download the clip. Inspired by this video — laser tagging buildings with a projector, done years ago and still magical. Try it right here No projector needed for this one — your mouse (or finger) is the laser. Pick a brush, flip on a mode, or play tic-tac-toe against the computer by drawing an X in a cell. How it works Everything runs in the browser — no install, no native app. 01Set upConnect a projector as a second screen and point a webcam at the projected area. Open the control window and the projector window (press F for fullscreen).

02CalibrateOne click flashes markers into the corners of the projection; the camera finds them and computes the camera→projector mapping. Then wave the laser for 4 seconds so the detector learns its brightness and colour. 03DrawEvery frame the camera finds the laser dot, maps it onto the projector, and the projector renders the stroke — right where you pointed. Hold the laser in the ☰ corner to open an on-wall menu.

Features Six brushes: round, marker, calligraphy, neon, spray, rainbow Wet ink that drips down the wall Spin your drawing as an extruded 3D object Fade-out mode and kaleidoscope mirroring Sparkle particle trail Tic-tac-toe against the computer, on the wall Coloured border around the drawable area Snapshots: save photo + drawing, download as files Laser-operated menu — no need to touch the laptop Reflection-robust tracking for shiny floors Works with green or red lasers Zero dependencies, MIT-licensed, open source What you need A laptop with Chrome, a projector (any HDMI projector works — it's just a second screen), a webcam that can see the projected area (the built-in one is fine), and a laser pointer. Green shows up best on camera. Start Laser Graffiti →