Ex Nihilo

Vector Output

After some idle speculation about taking my last posted sketch further, I’ve been going back and forth with a boutique print site called Wall Blank about doing a run of prints. This may be as far as I take them, or it may just be the tip of the iceberg; but more on that later (whenever I figure it out).

The immediate challenge was outputting something usable in print. I saw two options; figure out a way to use a canvas thousands of pixels across for the sake of saving out a bitmapped screen grab as a file high-resolution enough to print, or, instead find a way to output as vector.

The latter is clearly the better option and it turns out Processing has a built in PDF library that does all the hard work for you. It’s not totally straightforward; you can’t just dump the screen contents to a file, instead you have to capture the entire draw loop from the start and save that out. But even that is fairly simple. My draw loop ended up something like this:

void draw() {

  // setup the PDF save
  if (writePDF) {
    beginRecord(PDF, "frame-####.pdf");
  };

      // draw things here

  // now that the draw buffer is full,
  // dump the contents to a file
  if (writePDF) {
    endRecord();
    writePDF = false;
  };
};

The writePDF variable was an important check; without it I’d be writing PDFs on every frame. Instead I can toggle it on keypress and just capture a single frame:

void keyPressed() {
  // if 'p' is pressed, save out a PDF
  if (int(key) == 112) {
    writePDF = true;
  };
};

The resulting PDFs are surprisingly svelte; 8000 ellipses saved out to about files around 110k. My PNG screen grabs are usually at least 4 times as large.

What was particularly fun about this project is that I dared to ask whether each print could be unique, or if we were stuck working with the same source PDF for each print. I was pleasantly surprised to discover the printer was totally cool with printing a unique file for each one of the 100-print series, and happy to take advantage of that. With a slight modification to my draw loop:

void draw() {
  if ((createStuff > 0) && (createStuff < 101)) {
    beginRecord(PDF, "print-####.pdf");
  };

  if ((createStuff > 0) && (createStuff < 101)) {
    endRecord();
    createStuff++;
  };
};

...all I had to do was hit a key and wait about a minute, and voila, 100 totally unique prints, but united as a series with a common palette.

I'll make sure to mention it again on here when the prints are available for purchase, probably closer to the end of August.

Monday, August 10th, 2009 | Print | RSS 2.0

Tags: pdf, Print