Interaction Design WikiComputer Vision

Processing Keystone

There is a simple library called Keystone for Processing that enables projection mapping.

You can download the library using the built-in library manager in Processing.

Basic Example

The following example shows a basic usage with one mapped surface:

import deadpixel.keystone.*;

Keystone ks;
CornerPinSurface surface;

PGraphics offscreen;

void setup() {
  // Keystone will only work with P3D or OPENGL renderers, 
  // since it relies on texture mapping to deform
  size(800, 600, P3D);

  ks = new Keystone(this);
  surface = ks.createCornerPinSurface(400, 300, 20);
  // We need an offscreen buffer to draw the surface we
  // want projected, note that we're matching the resolution
  // of the CornerPinSurface.
  // (The offscreen buffer can be P2D or P3D)
  offscreen = createGraphics(400, 300, P3D);

void draw() {
  // Convert the mouse coordinate into surface coordinates
  // this will allow you to use mouse events inside the 
  // surface from your screen. 
  PVector surfaceMouse = surface.getTransformedMouse();

  // Draw the scene, offscreen
  offscreen.fill(0, 255, 0);
  offscreen.ellipse(surfaceMouse.x, surfaceMouse.y, 75, 75);

  // most likely, you'll want a black background to minimize
  // bleeding around your projection area
  // render the scene, transformed using the corner pin surface

void keyPressed() {
  switch(key) {
  case 'c':
    // enter/leave calibration mode, where surfaces can be warped 
    // and moved

  case 'l':
    // loads the saved layout

  case 's':
    // saves the layout;

Multiple Surfaces

You can map multiple interfaces by using multiple CornerPinSurface and PGraphics objects.