Hybrid Programming refers to py5’s ability to augment your py5 Sketch with Java code. This is very much like creating custom Processing extensions to enhance py5.

Hybrid Programming is documented on py5's website. The first two examples are code samples from the online documentation.

Here is a quick example of a py5 draw() method that uses Hybrid Programming:

def draw():
    colors = (255 * np.random.rand(N, 3)).astype(np.int32)
    points = np.random.rand(N, 2).astype(np.float32) * [py5.width, py5.height]
    # call Py5Utilities Java method
    py5.utils.drawColoredPoints(colors, points)

The drawColoredPoints() method is not a builtin method in py5; it is a user-created extension implemented in a special Java Py5Utilities class:

package py5utils;

import py5.core.Sketch;

public class Py5Utilities {

  public Sketch sketch;

  public Py5Utilities(Sketch sketch) {
    // This constructor is called before the sketch starts running. DO NOT use
    // Processing methods here, as they may not work correctly.
    this.sketch = sketch;
  }

  public void drawColoredPoints(int[][] colors, float[][] coords) {
    // iterate through the colors and coords arrays to draw multicolored points
    sketch.pushStyle();
    sketch.beginShape(Sketch.POINTS);
    for (int i = 0; i < colors.length; i++) {
      sketch.stroke(colors[i][0], colors[i][1], colors[i][2]);
      sketch.vertex(coords[i][0], coords[i][1]);
    }
    sketch.endShape();
    sketch.popStyle();
  }

}

The main idea is that any methods added to this Java Py5Utilities class will be made available to you through the py5.utils attribute. Use of this feature can greatly enhance the performance and capabilities of your py5 Python code. Refer to the online Hybrid Programming documentation to learn more.