Basic Tutorial

Here is a simple rotating box sketch using Camera3D.

First, import the library and create a variable for Camera3D:

import camera3D.Camera3D;

Camera3D camera3D;

Now create a PGraphics object and some floats. We'll need these for our sketch.

PGraphics label;

float rotX = 0;
float rotY = 0;
float rotZ = 0;

Next, the setup method. Notice in the size method I select P3D as the renderer. This is necessary.

Create an instance of Camera3D and tell it what color the background should be. The default color is white. In this example we use color(192), making the background a light gray.

Then use the default anaglyph renderer and configure some options. We are setting the divergence, or the gap between the left and right images, to 1 degree. This is the angle between the camera's target location and the left and right camera positions. Typical values are small positive numbers.

All default camera settings (position, target, perspective, etc) are identical to the regular Processing defaults.

void setup() {
  size(500, 500, P3D);
  camera3D = new Camera3D(this);

Finish the setup method by adding some text to the label PGraphics object.

  label = createGraphics(140, 50);
  label.textAlign(LEFT, TOP);
  label.text("Rotating Cube", 0, 0);

Now, something new: an optional preDraw method.

If this method is included in your sketch, it will be called ONCE before any calls to the draw method. Any code that you want to be executed one single time per frame should be located here.

In this case, this function will update the rotation of our box. IMPORTANT: code that updates state, such as the position of objects, needs to be moved to this preDraw method. If you are adding Camera3D functionality to an existing sketch, you may have some work to do separating out this aspect of your code.

void preDraw() {
  rotX += 0.5;
  rotY += 0.1;
  rotZ += 0.3;

And the draw method.

This looks like an ordinary draw method, which it is. Only difference is, in this sketch, the draw method will be executed TWICE. Processing will call the draw method once, but Camera3D will call the draw method a second time to re-render the scene with different camera settings.

IMPORTANT: If the code in the preDraw method was in the draw method, the cube would continue rotating between the first and second draw executions, harming the results. That's why a preDraw method is needed.

void draw() {
  fill(255, 255, 255);
  translate(width / 2, height / 2, -400);

Another optional method: postDraw.

If this method is included in your sketch, it will be called ONCE after all calls to the draw method. This is useful for post-generator drawing. Here we add the label to the corner.

void postDraw() {
  copy(label, 0, 0, label.width, label.height, width - label.width,
       height - label.height, label.width, label.height);

Both the preDraw and postDraw methods are optional. Camera3D automatically detects if your sketch has these methods and will call them at the correct times if they are present. They are useful for coping with the multiple calls to the draw method, and they are necessary for some libraries like ControlP5 to work correctly in a Camera3D sketch.

Here is an overview of the basic steps that take place for every frame in this sketch:

  1. Call preDraw method.

  2. Update Processing camera position to draw the right image.

  3. Call draw method.

  4. Copy the current rendered image, called a component frame, into a temporary buffer.

  5. Erase everything using the selected background color.

  6. Update Processing camera position to draw the left image.

  7. Call draw method again.

  8. Copy the new component frame into a second temporary buffer.

  9. Send component frames to the Generator to create the composite frame.

  10. Replace the current rendered image with the Generator's composite frame output.

  11. Call postDraw method, rendering the final output.

That's really all there is too it. I designed this to be as simple as possible. There is a lot of stuff happening behind the scenes, but you don't have to worry about that. The main thing I want you to remember is that the draw method is called multiple times. Move code that should only execute once to the preDraw method. That, plus a couple of extra lines in the setup method, and you've transformed your sketch into an anaglyph animation.

Now have a look at the result. Put on your 3D Glasses and be amazed!