Projection mapping — fitting light exactly onto real objects so a box glows on its faces and a window frame becomes a portal — used to require a laptop, a capture card, and desktop software with a stage-show learning curve. If you just want your living-room wall to breathe slow plasma tonight, that's the wrong tool. Here's the phone-sized version, start to finish.
No accounts, no media server, no API keys. With RoomCanvas everything runs locally on the phone and travels over your own network.
Put the projector roughly where you want it and point it at the target — angle and keystone don't need to be perfect, because the mapping corrects for them. Then get pixels flowing: cast to the Chromecast, pick the AirPlay target, plug in HDMI, or open the app's output link in a browser on the machine driving the projector. Nearby devices show up by name; one tap and the wall is live in about three seconds.
This is the actual "mapping" part, and there are two ways to do it:
Tell the app what you're mapping — a box, a wall, a door — and it projects a glowing quad with numbered corners. Drag each corner on your phone while watching the wall, not the screen; a beacon on the output marks the corner you're holding. When the glow hugs the real edges, you're mapped. For pixel-perfect edges, a calibrate mode walks corner by corner with fine trackpad-style control.
Point your phone's camera at the projected area and run a room scan. The projector flashes a short sequence of structured-light patterns (Gray codes), the camera decodes them, and every surface the projector can reach becomes a mapped shape — no dragging at all. It's the same technique 3D scanners use, running between your projector and your phone. Surfaces it finds can still be nudged afterward like any hand-drawn shape.
Each mapped surface takes its own content: live GPU shader looks (plasma, tunnels, aurora, neon skylines — 30+ of them), photos and videos from your library, or live widgets like a clock and weather that need zero API keys. Tap a look and it plays on the surface instantly, warped correctly to the shape you fit. Different surfaces can run different looks at the same time — rainbow in the window, soft plasma across the wall.
No. Mapping happens in software — the app pre-warps the image so it lands squarely on the surface regardless of where the projector sits. Brighter helps in lit rooms; that's the only spec that really matters.
Not for home-scale mapping. Those are professional stage tools. A phone that maps, renders, and casts directly replaces the whole desktop chain for walls, windows, boxes, and displays.
Then you don't need mapping — you need casting. Our free, open-source macOS app WallCast gets local files, your screen, or a live link onto any DLNA TV with every control free forever.
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Chromecast projection mapping: the three-second wall → · Support & troubleshooting