p5.brush.js

p5.brush.js adds natural drawing tools to p5.js — pencils, charcoal, markers, watercolor fills, hatch patterns, and vector fields that bend strokes organically. It's built for generative art and high-resolution printing.

Visit the library website here! (more examples soon)

🖌️ Try the interactive Brush Maker →
Design custom brushes with live preview and generate ready-to-paste brush.add() code.

🌊 Try the interactive Flow Field Generator → Design custom vector fields with live preview and generate ready-to-paste brush.addField() code.

▶️ Check the teaser live → Live on the p5.js Web Editor, where you can read and edit code.

Two builds

p5.brush ships in two flavors:

	p5 build	Standalone build
File	dist/p5.brush.js	dist/brush.js
Requires	p5.js 2.x + WEBGL canvas	Nothing — WebGL2 browser only
Canvas setup	createCanvas(w, h, WEBGL)	brush.createCanvas(w, h)
Transforms	p5's push/pop, translate, rotate, scale	brush.push/pop, brush.translate, etc.
Angle mode	Follows p5's angleMode()	brush.angleMode(brush.DEGREES | brush.RADIANS)
Seeding	randomSeed() / noiseSeed()	brush.seed() / brush.noiseSeed()
Frame flush	Automatic	brush.render() at end of each frame
Clear	p5's background()	brush.clear(color?)

This README covers the p5 build. For the standalone build see docs/standalone.md.

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Table of Contents

• Installation
• Quick Start
• Core Concepts in 1 Minute
• Features
• Reference
• Examples
• Contributing
• License
• Acknowledgements

Installation

Important note: p5.brush requires p5.js 2.x or higher.

Local Installation

To set up your project, add p5.min.js and p5.brush.js to your HTML file. You can download the latest version of the p5.brush.js library in the dist folder. Place the script tags in the following order:

<script src="path_to/p5.min.js"></script>
<script src="path_to/p5.brush.js"></script>

Replace path_to with the actual path to the script in your project directory or the URL if you are using a CDN.

Use a hosted version of the p5.brush.js library

Alternatively, you can link to a p5.brush.js file hosted online. All versions are stored in a CDN (Content Delivery Network). You can find a history of these versions in the p5.js CDN. In this case you can change the link to:

<!-- Online version of p5.brush -->
<script src="https://cdn.jsdelivr.net/npm/p5.brush@latest"></script>

Install with NPM and other modular-based apps

Install the npm package. p5.brush requires p5.js as a peer dependency for the p5 build.

npm install p5.brush --save

The package exposes two subpaths — pick the one that matches your build:

// p5 build (default) — requires p5.js 2.x
import * as brush from 'p5.brush'

// Standalone build — no p5.js required
import * as brush from 'p5.brush/standalone'

If you are using p5 and p5.brush as modules, you will need to use instance mode. Read below.

Note for p5 instance mode

In instance mode, p5 functions are scoped to a variable instead of the global namespace — useful when mixing with other libraries or using p5 as an ES module.

Call brush.instance(p) inside your sketch function before setup and draw. After that, all brush.* calls work normally without any p. prefix.

const sketch = (p) => {
  // Tell p5.brush which p5 instance to use
  brush.instance(p);

  p.setup = () => {
    // Canvas must be in WEBGL mode — brush initializes automatically
    p.createCanvas(700, 410, p.WEBGL);
  };

  p.draw = () => {
    p.background(240);
    brush.set("HB", "#333", 1);
    brush.line(100, 100, 400, 300);
  };
};

new p5(sketch);

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Quick Start

If you already know the basics of p5, this is the shortest path to drawing with p5.brush:

1. Create a WEBGL canvas.
2. Pick a brush with brush.set(name, color, weight).
3. Draw with a primitive like brush.line(), brush.rect(), or brush.circle().

function setup() {
  createCanvas(700, 410, WEBGL);
  background("#f6f1e8");
  brush.scaleBrushes(3);

  brush.set("HB", "#2f2a26", 1.4);
  brush.line(-220, -80, 180, 40);

  brush.fill("#d7c3a3", 120);
  brush.noStroke();
  brush.circle(120, 20, 70);

  brush.set("rotring", "#1f4b99", 0.8);
  brush.noFill();
  brush.hatch(7, 35);
  brush.rect(-140, 40, 120, 90, "center");
}

If you are new to the library, a good first sequence is:

• brush.scaleBrushes(...) if you are using built-in brushes
• brush.set(...) to choose the stroke brush
• brush.fill(...) or brush.hatch(...) if you want interior texture
• brush.line(), brush.rect(), brush.circle(), or brush.polygon() to draw

Core Concepts in 1 Minute

• p5.brush follows p5's drawing model: first you set drawing state, then you draw shapes.
• brush.set(), brush.stroke(), brush.strokeWeight(), brush.fill(), brush.hatch(), and related functions configure how upcoming shapes should look.
• brush.line(), brush.rect(), brush.circle(), brush.arc(), brush.beginShape(), and brush.polygon() actually draw geometry.
• brush.noStroke(), brush.noFill(), brush.noHatch(), and brush.noWash() turn parts of that state back off.
• Vector fields are optional. If you never call brush.field(...), your shapes still draw normally.
• Most sketches only need a small subset of the API: choose a brush, maybe add fill or hatch, then draw primitives.

You can think of the library in three layers:

• Style: choose how marks look with brush.set(), brush.fill(), brush.hatch(), and related state functions
• Geometry: draw lines and shapes with brush.line(), brush.rect(), brush.circle(), brush.beginShape(), and more
• Advanced control: add vector fields, custom brushes, clipping, buffers, and classes when you need them

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Features

p5.brush.js enhances the p5.js framework with a set of tools that allow for sophisticated drawing and rendering techniques.

• Custom Configuration: Customize your drawing strokes with the ability to select different buffers and leverage a custom random number generator to introduce variability in procedural designs.
• Vector Field Integration: Direct the motion of your brush strokes with vector fields, crafting fluid, dynamic visuals within your sketches.
• Dynamic Brush System: Select from an array of brushes, each offering distinct characteristics, to create a variety of effects and textures.
• Brush and Field Management: Manage and switch between brushes and vector fields with ease, adapting to the needs of your project seamlessly.
• Extensibility: Expand the library's capabilities by integrating your own custom brushes and vector fields, tailoring the toolset to your artistic vision.
• Custom Brush Tips: Load and use your own custom brush tip assets.
• Interactive Brush Tips: Utilize pressure-sensitive brush tips for interactive drawing, adding a level of responsiveness to your canvas work.
• Hatch Patterns: Implement hatching techniques with precision control over the patterns' density and orientation, enhancing your artwork with automated detailing.
• Intuitive Spline and Curve Generation: Generate smooth and accurate curves and splines effortlessly, simplifying the process of intricate path creation.
• Watercolor Fill System: Achieve the subtle nuances of watercolor with a digital fill system designed to blend and diffuse colors in a naturally fluid way.

With p5.brush.js, your digital canvas becomes a playground for innovation and expression, where each tool is fine-tuned to complement your unique creative process.

Reference

p5.brush.js provides a comprehensive API for creating complex drawings and effects. Below are the categorized functions and classes available in the library.

Table of Functions

Section	Functions	Section	Functions
Configuration	brush.load(), brush.scaleBrushes(), brush.instance()	Fill Operations	brush.fill(), brush.noFill(), brush.wash(), brush.noWash(), brush.fillBleed(), brush.fillTexture()
Vector Fields	brush.field(), brush.noField(), brush.refreshField(), brush.listFields(), brush.addField(), brush.wiggle()	Hatch Operations	brush.hatch(), brush.noHatch(), brush.hatchStyle(), brush.mass(), brush.noMass()
Brush Management	brush.box(), brush.add(), brush.clip(), brush.noClip()	Primitives	brush.line(), brush.flowLine(), brush.beginStroke(), brush.move(), brush.endStroke(), brush.spline(), brush.rect(), brush.circle(), brush.arc(), brush.beginShape(), brush.vertex(), brush.endShape(), brush.polygon()
Stroke Operations

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Configuration

This section covers functions for initializing the drawing system and configuring how the library behaves in your sketch. In particular, brush.scaleBrushes() is usually important when you use the built-in brushes.

Seeding: p5.brush automatically hooks into p5's randomSeed() and noiseSeed(). Calling either of those functions seeds both p5 and the library simultaneously — no separate brush.seed() call is needed.

• brush.load(buffer)

  • Description: Redirects brush drawing to a secondary canvas target. Not needed for the main canvas — the library initializes on the first brush drawing operation after createCanvas(..., WEBGL). Pass a p5.Graphics buffer or an active p5.Framebuffer to draw into that target instead; call brush.load() with no argument to switch back to the main canvas. Framebuffers created from p5.Graphics are not supported.

  • Parameters:

    • buffer (p5.Graphics | p5.Framebuffer): Optional. An offscreen target to draw into.

  • How to use it:

    • p5.Graphics: create it with WEBGL, call brush.load(pg), draw with brush functions, then call brush.load() to restore the main canvas before presenting it with image(pg, ...).
    • p5.Framebuffer: create it from the main sketch with createFramebuffer(...), enter its draw() or begin() / end() scope, call brush.load(fb) while it is active, draw with brush functions, then call brush.load() again after leaving the framebuffer scope.
    • brush.load(...) only changes the target used by p5.brush. If you also use native p5 drawing calls, call them on the same target yourself, for example pg.background(...) for p5.Graphics.
    • pg.createFramebuffer() is not supported.

  • Example (draw into a buffer):

    function setup() {
      createCanvas(400, 400, WEBGL);
      brush.load();
      brush.set("HB", "black", 1);
      brush.rect(40, 40, 150, 100);
    
      // Switch to a buffer
      let buffer = createGraphics(200, 300, WEBGL);
      brush.load(buffer);
      brush.set("HB", "black", 1);
      brush.rect(40, 40, 150, 100);
      image(buffer, 20, 40);
    
      // Switch back to main canvas
      brush.load();
    }
    

  • Example (draw into a framebuffer):

    function setup() {
      createCanvas(400, 400, WEBGL);
      brush.load();
    
      const layer = createFramebuffer({ width: 200, height: 200 });
    
      layer.draw(() => {
        brush.load(layer);
        brush.set("HB", "black", 1);
        brush.circle(100, 100, 80);
      });
    
      brush.load();
      image(layer, 20, 20);
    }
    

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• brush.scaleBrushes(scale)
  • Description: Adjusts the global scale of all currently registered brush parameters, including weight, scatter, and spacing, based on the given scaling factor.
  • Parameters:
    • scale (Number): The scaling factor to be applied to the brush parameters.
  • Important: If you are using the built-in brushes, brush.scaleBrushes() is usually not optional in practice. Without it, the built-in brushes will often look much too small or otherwise wrong for your canvas size. For a 600x600 canvas, brush.scaleBrushes(3) is a good starting point, but the final value should still be confirmed visually.
  • Note: This affects the brushes that already exist when you call it. If you only want the built-in brushes scaled, call it before adding custom brushes. If you add custom brushes later, call brush.scaleBrushes() again to scale them too.
  • Usage:

    // Usually needed when working with built-in brushes
    brush.scaleBrushes(3);
    

    Use brush.scaleBrushes() early in setup() so the built-in brushes match your canvas scale before you start drawing.

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• brush.instance(p)
  • Description: Call this inside your sketch function before setup and draw when using p5 in instance mode. Tells p5.brush which p5 instance to render into. After calling this, all brush.* functions work normally — no need to prefix them with p..
  • Parameters:
    • p (p5): The p5 instance passed as the argument to your sketch function.
  • Example:

    const sketch = (p) => {
      // Must be called before setup/draw
      brush.instance(p);
    
      p.setup = () => {
        // Canvas must be WEBGL
        p.createCanvas(700, 410, p.WEBGL);
        brush.load();
      };
    
      p.draw = () => {
        p.background(240);
        brush.set("HB", "#333", 1);
        brush.line(100, 100, 400, 300);
      };
    };
    
    new p5(sketch);
    

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Vector Fields

Vector fields let you bend and redirect strokes so they follow a flow across the canvas. If you do not use them, p5.brush still works like a normal drawing library.

Basic vector-field functions

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• brush.field(name)
  • Description: Activates a named vector field. When a vector field is active, it influences the flow and direction of the brush strokes for shapes drawn thereafter. It is important to note that certain shapes may be exempt from this influence; such exceptions will be clearly documented in the API for each specific geometry.
  • Parameters:
    • name (String): The identifier for the vector field to be activated. This can be a name of one of the predefined fields or a custom field created with brush.addField().
  • Default Fields: The library comes with a set of built-in vector fields: hand, curved, zigzag, waves, seabed, spiral, and columns. These, as well as any custom fields added, can be activated using this function.
  • Usage:

    // To activate the "waves" vector field
    brush.field("waves");
    
    // To activate a custom vector field named "myCustomField"
    brush.field("myCustomField");
    

    Once a vector field is activated, it affects how the subsequent shapes are drawn, aligning them with its directional flow, unless stated otherwise in the documentation

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• brush.noField()
  • Description: Deactivate the currently active vector field, returning the drawing behavior to its default state where shapes are not influenced by any vector field.
  • Usage:

    brush.noField();
    

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• brush.wiggle(wiggle)
  • Description: Activate the built-in "hand" vector field with a given wiggle intensity. A shorthand for adding a subtle hand-drawn wobble to strokes without calling brush.field("hand") directly.
  • Parameters:
    • wiggle (Number): Intensity of the wobble, e.g. 1–10.
  • Usage:

    brush.wiggle(3);
    

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• brush.refreshField(time)
  • Description: Updates the current vector field values using its time-dependent generator function. Ideal for animations that require the vector field to change over time, influencing the movement of strokes and shapes in a natural way.
  • Parameters:
    • time (Number): The time input for the vector field generator function, typically related to the frame count.
  • Usage:

    // In the draw loop, refresh the vector field based on the frame count
    function draw() {
      brush.refreshField(frameCount / 10);
      // Additional drawing code
    }
    

    This function will invoke the generator function of the active vector field with the provided time argument, allowing the field to evolve and create fluid, dynamic animations in the rendering.

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• brush.listFields()
  • Description: Retrieve an array containing the names of all available vector fields, including built-in fields and any custom fields added with brush.addField().
  • Returns: Array<string> - An array of vector field names.
  • Usage:

    let fieldNames = brush.listFields();
    for (let name of fieldNames) {
      console.log(name);
    }
    

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Advanced vector-field functions

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• brush.addField(name, generatorFunction, options)
  • Description: Creates your own custom vector field. A vector field is just a grid of angles — each cell tells the brush "point in this direction". You give the field a name and a function that fills the grid. Once added, activate it with brush.field(name) just like any built-in field.
  • Parameters:
    • name (String): Any name you want, e.g. "myField".
    • generatorFunction (Function): A function (t, field) => field that fills every cell of the grid with an angle and returns it. t is a time value you can use for animation (pass it via brush.refreshField(t)).
    • options (Object): Optional configuration for custom field angles.
      • angleMode: "degrees" (default) or "radians". This controls how the values written into field[column][row] are interpreted.
  • How the grid works: field is a 2D array — field[column][row]. You loop through every column and row and set each cell to an angle. By default those angles are interpreted as degrees. Small angles (±10°) make subtle curves; large ones (±90° or more) make dramatic bends.
  • Simplest example — a diagonal flow that slowly rotates over time:

    brush.addField("diagonal", function(t, field) {
        for (let col = 0; col < field.length; col++) {
            for (let row = 0; row < field[0].length; row++) {
                field[col][row] = 45 + t * 10; // 45° angle, changes with time
            }
        }
        return field; // always return field at the end!
    });
    
    brush.field("diagonal"); // activate it
    

  • Tip: You don't have to use t at all if you don't need animation. Just fill the grid and return it.

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Brush Management

This section covers choosing brushes, adding your own brushes, and clipping where strokes are allowed to appear.

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• brush.box()
  • Description: Retrieves an array containing the unique names of all available brushes. This function is useful for accessing the variety of brushes included in the library, which range from different pencil types to markers and specialized brushes like the hatch brush. Of course, the function will also return the custom brushes you've created.
  • Returns: Array<string> - An array listing the names of all brushes.
  • Default Brushes: The library includes a default set of 11 brushes: 2B, HB, 2H, cpencil, pen, rotring, spray, marker, marker2, charcoal, and hatch_brush (for clean hatching).
  • Usage:

    // Retrieve a list of all available brush names
    let brushes = brush.box();
    console.log(brushes); // Logs the array of brush names
    

    brush.box() allows you to explore and select from the various brushes, facilitating the choice of the appropriate brush for different artistic needs.

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• brush.add(name, params) — Design your brush visually with the Brush Maker ↗

  • Description: Creates a new brush with your own settings. Once added, you use it just like any built-in brush with brush.set("myBrush", color, size).

  • Parameters:

    • name (String): A name for your brush — pick anything you like.
    • params (Object): An object with the brush settings:
      • type: The kind of brush tip. Choose one: "default" (pencil-like), "spray" (scattered dots), "marker" (flat solid), "custom" (you draw the tip shape), "image" (use a photo as the tip).
      • weight: How thick the brush is, in canvas units.
      • scatter: How much the stroke wobbles sideways. Higher = more spread. (in canvas units)
      • sharpness: A number from 0 to 1. Lower = softer/fuzzier edge. Only matters for "default" type.
      • grain: Controls how dense the texture is. Higher = smoother, more continuous line. Only matters for "default" and "spray" types.
      • opacity: How opaque each mark is, from 0 to 255. Pressure also affects this.
      • spacing: Gap between brush tip stamps along the stroke. 1 means no overlap, lower values create denser strokes.
      • pressure: Controls how the brush size changes from start to end of a stroke. Use a simple array — the easiest way:
        • [start, end] — e.g. [2, 0.5] starts thick and gets thin.
        • [start, middle, end] — e.g. [0.5, 2, 0.5] starts thin, swells in the middle, ends thin.
        • Or a function (t) => value where t goes from 0 (start) to 1 (end), for full control.
        • These simple/custom pressure modes include a subtle amount of per-stroke variation automatically, so repeated strokes feel less mechanical.
        • Advanced option for power users: use the library's built-in Gaussian pressure profile explicitly with an object like { mode: "gaussian", curve: [0.15, 0.2], min_max: [1.1, 0.9] }. curve adjusts the wobble and asymmetry of the pressure envelope, while sets the mapped pressure range. This is the same family of pressure logic used by the built-in brushes.

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• brush.clip(clippingRegion)
  • Description: Sets a rectangular clipping region for all subsequent brush strokes. When this clipping region is active, brush strokes outside this area will not be rendered. This is particularly useful for ensuring that strokes, such as lines and curves, are contained within a specified area. The clipping affects only stroke and hatch operations, not fill operations. The region is interpreted in the same coordinate space as your brush drawing calls, with the current p5 transform captured when brush.clip() is called. The clipping remains in effect for all strokes drawn after the call to brush.clip() until brush.noClip() is used.
  • Parameters:
    • clippingRegion (Array): An array defining the clipping region as [x1, y1, x2, y2], with (x1, y1) and (x2, y2) being the corners of the clipping rectangle.
  • Usage:

    // Set a clipping region
    brush.clip([10, 10, 250, 200]);
    // Draw a line - it will be clipped according to the region
    brush.line(100, 90, 300, 40);
    
    // Remove the clipping region
    brush.noClip();
    // Draw another line - it will not be clipped
    brush.line(0, 0, 200, 300);
    

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• brush.noClip()
  • Description: Disables the current clipping region, allowing subsequent brush strokes to be drawn across the entire canvas without being clipped. Use this function to revert to the default state where strokes are unrestricted.
  • Usage:

    // Disable the clipping region
    brush.noClip();
    

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Stroke Operations

These functions control stroke appearance: which brush is active, what color it uses, and how thick it should be.

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• brush.set(brushName, color, weight)
  • Description: Selects and sets up the current brush with a specific name, color, and weight. This function is crucial for preparing the brush to draw strokes with the desired characteristics.
  • Parameters:
    • brushName (String): The name of the brush to be used.
    • color (String|p5.Color): The color for the brush, which can be specified as a HEX string or a p5.Color object.
    • weight (Number): The weight or size of the brush.
  • Note: This function will automatically activate stroke mode for subsequent geometries.
  • Usage:

    // Set the "HB" brush with a specific blue color and weight factor 1
    brush.set("HB", "#002185", 1);
    

    By using brush.set(), you can quickly switch between different brushes, colors, and sizes, allowing for dynamic and varied stroke applications in your artwork.

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• brush.pick(brushName)
  • Description: Selects the current brush type based on the specified name. This function is used to change the brush type without altering its color or weight.
  • Parameters:
    • brushName (String): The name of the brush to set as current.
  • Usage:

  // Set the current brush to "charcoal"
  brush.pick("charcoal");
  

  Use brush.pick() to switch between different brush types while maintaining the current color and weight settings.

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• brush.stroke(r, g, b) or brush.stroke(color)
  • Description: Sets the color of the current brush. This function can take either RGB color components or a CSS color string/p5.Color object. It also activates stroke mode for subsequent shapes.
  • Parameters:
    • r (Number|String|p5.Color): The red component of the color, a CSS color string, or a p5.Color object.
    • g (Number): Optional. The green component of the color.
    • b (Number): Optional. The blue component of the color.
  • Usage:

    // Set the brush color using RGB values
    brush.stroke(105, 111, 34);
    // Or set the brush color using a HEX string
    brush.stroke("#002185");
    

    Use brush.stroke() to define the color of your brush strokes, enabling a diverse palette for your artwork.

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• brush.noStroke()
  • Description: Disables the stroke for subsequent drawing operations. This function is useful when you want to draw shapes without an outline.
  • Usage:

    // Disable stroke for the upcoming shapes
    brush.noStroke();
    

    brush.noStroke() is essential for creating drawings where only fill and no outline is desired.

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• brush.strokeWeight(weight)
  • Description: Sets the weight or size of the current brush. The specified weight acts as a multiplier to the base size of the brush, allowing for dynamic adjustments.
  • Parameters:
    • weight (Number): The weight to set for the brush.
  • Returns: None.
  • Usage:

    // Set the brush stroke weight to 2.3 times the base size
    brush.strokeWeight(2.3);
    

    brush.strokeWeight() provides the flexibility to easily adjust the thickness of your brush strokes, enhancing the expressiveness of your drawing tools.

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Fill Operations

These functions control how closed shapes are filled. fill() paints watercolour: each shape is grown from Tyler Hobbs' layered-polygon method and painted as a dried wash, with an irregular edge, a pigment ring where it dried, granulation, pooling, occasional drops and blooms, and pigments that separate into slightly different hues. wash() paints flat colour.

Fills drawn in the same frame interact: a fill whose edge touches a recent one that is still wet loses its edge there and feathers into it. The paper dries at every brush.render() (and at the end of p5's draw()). Fills are seeded: call brush.seed() with the same value each frame to keep an animated fill's look stable.

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• brush.fill(a, b, c, d) or brush.fill(color, opacity)
  • Description: Sets the fill color and opacity for subsequent shapes, activating fill mode. This function can accept either RGB color components with opacity or a CSS color string/p5.Color object with an optional opacity.
  • Parameters:
    • a (Number|String|p5.Color): The red component of the color or grayscale value, a CSS color string, or a p5.Color object.
    • b (Number): Optional. The green component of the color or grayscale opacity if two arguments are used.
    • c (Number): Optional. The blue component of the color.
    • d (Number): Optional. The opacity of the color, 0 - 255.
  • Usage:

    // Set the fill color using RGB values and opacity
    brush.fill(244, 15, 24, 75);
    // Or set the fill color using a HEX string and opacity
    brush.fill("#002185", 110);
    

    brush.fill() allows for detailed control over the color and transparency of the fill.

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• brush.noFill()
  • Description: Disables the fill for subsequent drawing operations. Useful for creating shapes or lines without a fill.
  • Usage:

    // Disable fill for the upcoming shapes
    brush.noFill();
    

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• brush.wash(color, opacity)
  • Description: Enables a fast solid fill pass for subsequent shapes. Unlike fill(), wash() does not simulate watercolor bleed or texture; it draws a direct flat color with the given opacity.
  • Parameters:
    • color (String|p5.Color): The wash color.
    • opacity (Number): Opacity from 0 to 255.
  • Usage:

    brush.wash("#f7e4a0", 255);
    brush.circle(width / 2, height / 2, 180);
    brush.noWash();
    

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• brush.noWash()
  • Description: Disables wash mode for subsequent geometry.
  • Usage:

    brush.noWash();
    

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• brush.fillBleed(strength, direction, angle)
  • Description: Adjust the bleed intensity for the fill operation, mimicking the edge diffusion of watercolor paints.
  • Parameters:
    • strength (Number): The intensity of the bleed effect, ranging from 0 to 1.
    • direction (String): Optional. "out" or "in". Defines the direction of the bleed effect.
    • angle (Number): Optional. Sets the watercolor wash direction in the current angle mode; omit for random direction.
  • Usage:

    brush.fillBleed(0.3, "out", 0); // left to right
    

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• brush.fillTexture(textureStrength, borderIntensity, scatter?, split?)
  • Description: Adjusts the texture of watercolour fills.
  • Parameters:
    • textureStrength (Number): Granulation (pigment settling in the paper's grain) and, at higher values, reticulation (a fine cell pattern), from 0 to 1.
    • borderIntensity (Number): Strength of the pigment ring left at the edge as the wash dried, from 0 to 1.
    • scatter (Boolean, optional, default true): Whether to draw the sparse scattered polygon layers that add texture inside the shape. Set to false for a cleaner gradient.
    • split (Number, optional, default 0.15): How far the paint separates into a warmer and a cooler pigment across the wash, from 0 (one pigment) to 1.
  • Usage:

    // Set the fill texture and border intensity
    brush.fillTexture(0.6, 0.4);
    
    // Disable scatter layers for a cleaner gradient
    brush.fillTexture(0.6, 0.4, false);
    
    // Stronger hue variation inside each wash
    brush.fillTexture(0.6, 0.4, true, 0.4);
    

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Hatch Operations

These functions control hatching and massing inside shapes, using repeated lines or layered marks to build tone and texture.

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• brush.hatch(dist, angle, options)
  • Description: Activates hatching with specified parameters for subsequent geometries. This function enables the drawing of hatching patterns with controlled line spacing, angle, and additional stylistic options.
  • Parameters:
    • dist (Number): The distance between hatching lines, in canvas units.
    • angle (Number): The angle at which hatching lines are drawn. It is interpreted using p5's current angleMode() when brush.hatch() is called.
    • options (Object): Optional settings to affect the hatching style, including:
      • rand: Randomness in line placement (0 to 1 or false).
      • continuous: Whether to connect the end of a line with the start of the next.
      • gradient: Modifies the distance between lines to create a gradient effect (0 to 1 or false).
      • Defaults to {rand: false, continuous: false, gradient: false}.
  • Usage:

    // Set hatching with specific distance, angle, and options
    brush.hatch(5, 30, {rand: 0.1, continuous: true, gradient: 0.3});
    

---

• brush.noHatch()
  • Description: Disables hatching for subsequent shapes. Use this function to return to normal drawing modes without hatching.
  • Usage:

    // Disable hatching for upcoming shapes
    brush.noHatch();
    

---

• brush.hatchStyle(brushName, color, weight)
  • Description: Set the brush type, color, and weight specifically for hatching. If not called, hatching will use the parameters defined by the current stroke settings.
  • Parameters:
    • brushName (String): The name of the brush to use for hatching.
    • color (String|p5.Color): The color for the brush, either as a CSS string or a p5.Color object.
    • weight (Number): The weight or size of the brush for hatching.
  • Usage:

    brush.hatchStyle("rotring", "green", 1.3);
    

---

• brush.mass(brushName, color, options)
  • Description: Enables massing for subsequent shapes. Massing builds layered hand-filled value using internally generated hatch geometry and curved gestures rather than explicit watercolor fills.
  • Parameters:
    • brushName (String): Brush used for the mass strokes.
    • color (String|p5.Color): Color of the mass.
    • options (Object): Optional settings:
      • precision: 0 to 1. Higher values reduce jitter and randomness.
      • strength: 0 to 1. Controls how many of the three internal layers are drawn.
      • gradient: 0 to 1. Passed through to hatch generation for spacing variation.
      • outline: true or false. If true, the first polygon is also outlined.
      • style: "arcs" (default) or "scribble" (experimental). Arcs sweep across the whole shape in a few layers. Scribble builds the fill from many short, hand-like back-and-forth gestures that start at evenly scattered points, drift in direction and size, and are cut where they leave the shape. With scribble, strength sets how much the gestures overlap, gradient makes them lighter and shorter across the shape, and precision is not used.
      • length (scribble only): the longest a single gesture can be, in canvas pixels. Gestures vary between about 40% and 100% of it. When omitted, gestures are sized to the shape.
      • follow (scribble only): 0 to 1. How much gestures near the outline turn to run along it. Default 0.25.
  • Usage:

    brush.mass("pastel", "#4b6cb7", {
      precision: 0.55,
      strength: 0.9,
      gradient: 0.35,
      outline: true,
    });
    brush.circle(width / 2, height / 2, 180);
    
    // Experimental scribble style
    brush.mass("HB", "#2a2a2a", { style: "scribble", length: 60, follow: 0.3 });
    brush.rect(100, 100, 200, 150);
    

---

• brush.noMass()
  • Description: Disables massing for subsequent geometry.
  • Usage:

    brush.noMass();
    

---

In essence, the hatching system activates hatches for subsequent shapes, similarly to stroke and fill operations. However, you can also directly hatch multiple objects at once, including their intersections, as described below.

• brush.hatchArray(polygons)
  • Description: Creates a hatching pattern across specified polygons. This function applies the set hatching parameters to a single polygon or an array of polygons.
  • Parameters:
    • polygons (Array|Object): The polygon(s) to apply the hatching. Can be a single polygon object or an array of polygon objects.
  • Note: This is not the main, but an alternative way of applying hatches. Read above.
  • Usage:

    // Define an array of polygons (reference in the classes section)
    let myPolygons = []
    for (let i = 0; i < 10; i++) {
       // We're creating 10 random triangles here
    			let p = new brush.Polygon([
          [random(width), random(height)],
          [random(width), random(height)],
          [random(width), random(height)],  
       ])
       myPolygons.push(p)
    }
    // Create hatching across specified polygons
    brush.hatchArray(myPolygons);
    

    brush.hatchArray() provides an efficient way to apply complex hatching patterns to a set of defined shapes.

---

• brush.massArray(polygons)
  • Description: Applies the current mass() state to a single brush.Polygon or an array of brush.Polygon objects as one combined multi-layer gesture. The array is treated as combined layers: the first polygon defines the outer boundary, additional polygons act as holes or inner layers via even-odd logic.
  • Parameters:
    • polygons (Array|Object): A single brush.Polygon or an array of brush.Polygon objects to mass.
  • Note: Like hatchArray(), this is an alternative to letting shapes pick up mass state automatically — use it when you need to treat multiple polygons as a single gesture.
  • Usage:

    // Define two nested polygons — outer boundary and inner hole
    let outer = new brush.Polygon([[50,50],[350,50],[350,350],[50,350]]);
    let inner = new brush.Polygon([[100,100],[300,100],[300,300],[100,300]]);
    let myPolygons = [outer, inner];
    
    // Apply mass to both as one combined gesture
    brush.mass("HB", "#002185", { strength: 1 });
    brush.massArray(myPolygons);
    

    brush.massArray() treats the array as layered geometry, so the inner polygon creates a hole via even-odd logic rather than being massed independently.

---

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Primitives

These are the functions that actually draw lines, paths, and shapes using the current stroke, fill, and hatch settings.

Lines, Strokes, Splines, and Plots

The following functions are only affected by stroke() operations, completely ignoring fill() and hatch().

---

• brush.line(x1, y1, x2, y2)
  • Description: Draws a line from one point to another using the current brush settings. This function is affected only by stroke operations and will not produce any drawing if noStroke() has been called.
  • Parameters:
    • x1 (Number): The x-coordinate of the start point.
    • y1 (Number): The y-coordinate of the start point.
    • x2 (Number): The x-coordinate of the end point.
    • y2 (Number): The y-coordinate of the end point.
  • Usage:

    // Set the brush color and draw a line
    brush.stroke("red");
    brush.line(15, 10, 200, 10);
    

---

• brush.flowLine(x, y, length, dir)
  • Description: Draws a flow line that adheres to the currently selected vector field. Flow lines are defined by a starting point, length, and direction. They are useful for creating strokes that dynamically follow the flow of the vector field.
  • Parameters:
    • x (Number): The x-coordinate of the starting point.
    • y (Number): The y-coordinate of the starting point.
    • length (Number): The length of the line.
    • dir (Number): The direction in which to draw the line, measured anticlockwise from the x-axis and interpreted using the current p5 angleMode().
  • Usage:

    // Set a vector field and draw a flow line
    brush.field("seabed");
    brush.flowLine(15, 10, 185, 0);
    

---

These three functions provide advanced control over the creation of strokes/paths, allowing for custom pressure and direction at different points along the path. Think of them as bodily movements performed with the hands. You can create two types of strokes: "curve" or "segments". For curved strokes, the curvature at any point is interpolated between the nearest control points.

These functions allow for the creation of strokes with varied pressures and directions, mimicking the organic nature of hand-drawn strokes. For an application of these principles, see: Enfantines II

• brush.beginStroke(type, x, y)

  • Description: Initializes a new stroke, setting the type and starting position. The type determines the kind of Plot to create, either a "curve" or "segments".
  • Parameters:
    • type (String): The type of the stroke, either "curve" or "segments".
    • x (Number): The x-coordinate of the starting point of the stroke.
    • y (Number): The y-coordinate of the starting point of the stroke.
  • Usage:

    // Begin a new curve stroke
    brush.beginStroke("curve", 15, 30);
    

• brush.move(angle, length, pressure)

  • Description: Add a segment to the stroke, defining its path by specifying the angle, length, and pressure. Use between brush.beginStroke() and brush.endStroke() to outline the stroke's trajectory and characteristics.
  • Parameters:
    • angle (Number): The initial angle of the segment, relative to the canvas, measured anticlockwise from the x-axis.
    • length (Number): The length of the segment.
    • pressure (Number): The pressure at the start of the segment, influencing properties like width.
  • Usage:

    brush.move(30, 150, 0.6);
    brush.move(75, 40, 1.1);
    

• brush.endStroke(angle, pressure)

  • Description: Completes the stroke path and triggers its rendering. This function defines the angle and pressure at the last point of the stroke path.
  • Parameters:
    • angle (Number): The angle of the curve at the end point of the stroke path.
    • pressure (Number): The pressure at the end of the stroke.
  • Usage:

    // Complete the stroke with a specific angle and pressure
    brush.endStroke(-45, 0.8);
    

---

• brush.spline(array_points, curvature)
  • Description: Draw a spline curve through a series of control points. The curve connects the start and end points directly, using intermediate points to shape the path. These splines are segmented paths with rounded corners.
  • Parameters:
    • array_points (Array<Array>): An array of points, where each point is [x, y] or [x, y, pressure]. The optional pressure value at each point influences brush width along the curve.
    • curvature (Number): Optional. The curvature of the spline, ranging from 0 to 1. A value of 0 produces straight segments.
  • Returns: brush.Plot — the rendered plot. Store it to apply .hatch(), .mass(), .fill(), or .draw() later at a different position.
  • Note: This is a simplified alternative to beginShape() - endShape() operations, useful for certain stroke() applications.
  • Usage:

    let points = [[30, 70], [85, 20, 1.5], [130, 100], [180, 50]];
    brush.spline(points, 0.5);
    

---

Shapes and Polygons

The following functions are affected by stroke(), fill() and hatch() operations.

---

• brush.rect(x, y, w, h, mode)
  • Description: Draw a rectangle on the canvas using the current stroke, fill, and hatch settings. Rectangles are influenced by active vector fields.
  • Parameters:
    • x (Number): The x-coordinate of the rectangle.
    • y (Number): The y-coordinate of the rectangle.
    • w (Number): The width of the rectangle.
    • h (Number): The height of the rectangle.
    • mode (String): Optional. "corner" (default) positions (x, y) at the top-left corner. "center" draws the rectangle centered at (x, y).
  • Usage:

    brush.noStroke();
    brush.noHatch();
    brush.fill("#002185", 75);
    brush.rect(150, 100, 50, 35, "center");
    

---

• brush.circle(x, y, radius, r)
  • Description: Draw a circle using the current stroke, fill, and hatch settings. Circles are affected by vector fields, so their outlines follow the active field just like other field-aware shapes.
  • Parameters:
    • x (Number): The x-coordinate of the circle's center.
    • y (Number): The y-coordinate of the circle's center.
    • radius (Number): The radius of the circle.
    • r (Number|Boolean): Optional. Hand-drawn irregularity amount. Values around 0 to 1 give subtle variation; true behaves like a strong irregularity.
  • Returns: [plot, offsetX, offsetY] — the brush.Plot and the top-left drawing offset. Pass these to plot.hatch(offsetX, offsetY), plot.mass(offsetX, offsetY), etc. to reuse the geometry.
  • Usage:

    brush.circle(100, 150, 75, true);
    

---

• brush.arc(x, y, radius, start, end)
  • Description: Draw an arc (partial circle) using the current brush settings. The arc is drawn as a stroke only — fill() is not applied.
  • Parameters:
    • x (Number): The x-coordinate of the center.
    • y (Number): The y-coordinate of the center.
    • radius (Number): The radius of the arc.
    • start (Number): Start angle interpreted using the current p5 angleMode().
    • end (Number): End angle interpreted using the current p5 angleMode().
  • Returns: brush.Plot — the rendered plot, or null when start equals end (zero sweep). Store it to redraw or apply effects at a different position.
  • Usage:

    brush.arc(200, 200, 50, 0, Math.PI);
    

---

These three functions perform similarly to the p5.js beginShape(), vertex(), and endShape() functions, although their curvature calculation is very different. They allow you to draw custom shapes with fine control over brush pressure at different points of the perimeter.

• brush.beginShape(curvature)

  • Description: Initiates the creation of a custom shape by starting to record vertices. An optional curvature can be defined for the vertices.
  • Parameters:
    • curvature (Number): Optional. A value from 0 to 1 that defines the curvature of the shape's edges.
  • Returns: None.
  • Usage:

    // Begin defining a custom shape with a specified curvature
    brush.beginShape(0.3);
    

• brush.vertex(x, y, pressure)

  • Description: Adds a vertex to the custom shape currently being defined. The function is used between brush.beginShape() and brush.endShape() calls. An optional pressure parameter can be applied at each vertex.
  • Parameters:
    • x (Number): The x-coordinate of the vertex.
    • y (Number): The y-coordinate of the vertex.
    • pressure (Number): Optional. The pressure at the vertex, affecting properties like width.
  • Returns: None.
  • Usage:

    // Add vertices to the custom shape
    brush.vertex(50, 100);
    brush.vertex(100, 150, 0.5);
    brush.vertex(150, 100);
    

• brush.endShape(a)

  • Description: Complete the custom shape, finalizing the recording of vertices, and render it with the current stroke, fill, and hatch settings.
  • Parameters:
    • a (Boolean): Optional. Pass true to close the shape (connect the last vertex back to the first). Pass false or omit to leave the shape open.
  • Returns: brush.Plot — the rendered plot for the completed shape. Store it to apply .hatch(), .mass(), .fill(), or .draw() later at a different position.
  • Usage:

    // Finish the custom shape and close it
    brush.endShape(true);
    // Or leave it open
    brush.endShape(false);
    

---

• brush.polygon(pointsArray)
  • Description: Creates and draws a polygon based on a provided array of points. This function is useful for drawing shapes that are not affected by vector fields, offering an alternative to the beginShape() and endShape() approach.
  • Parameters:
    • pointsArray (Array): An array of points, where each point is an array of two numbers [x, y].
  • Returns: brush.Polygon — the polygon instance. Store it to call .hatch(), .mass(), .fill(), or .draw() later, or pass it to brush.hatchArray() / brush.massArray().
  • Note: This is a simplified alternative to beginShape() - endShape() operations, useful for certain fill() and hatch() applications.
  • Usage:

    // Define a polygon using an array of points
    let points = [[x1, y1], [x2, y2], ...];
    brush.polygon(points);
    

    brush.polygon() is ideal for drawing fixed shapes that remain unaffected by vector fields, providing precise control over their form and appearance.

---

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Composing Shapes

The drawing primitives return their geometry — a brush.Polygon from brush.polygon(), a brush.Plot from brush.arc() / brush.spline() / brush.endShape(), or [plot, x, y] from brush.circle(). Store the return value to transform, redraw, or apply effects to the same geometry later, independently of when it was drawn.

// Draw once; reuse the geometry for hatching and massing
const frame = brush.polygon([[50,50],[350,50],[350,350],[50,350]]);

// Hatch the stored polygon with the current hatch state
brush.hatch(8, Math.PI / 4);
frame.hatch();

// Mass the same geometry with the current mass state
brush.mass("pastel", "#4b6cb7", { strength: 0.8 });
frame.mass();

To apply effects to multiple polygons as a single gesture (with even-odd hole logic), pass an array to brush.hatchArray() or brush.massArray().

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Exposed Classes

Exposed Classes provide foundational elements for creating and manipulating shapes and paths, as well as interacting with vector-fields in a more advanced manner.

---

Class: brush.Polygon

• Description: Represents a polygon defined by a set of vertices. The Polygon class is essential for creating and working with multi-sided shapes, offering various methods to manipulate and render these shapes.

• Constructor:

  • brush.Polygon(pointsArray)
    • pointsArray (Array): An array of points, where each point is an array of two numbers [x, y].

• Methods:

  • .intersect(line)
    • Intersects the polygon with a given line, returning all intersection points.
    • Parameters:
      • line (Object): A line object with properties point1 and point2.
    • Returns: Array of objects, each with x and y properties, representing the intersection points.
  • .draw(brush, color, weight)
    • Draws the polygon on the canvas, following the current stroke state or the provided params.
  • .fill(color, opacity, bleed, texture, border, direction, angle)
    • Fills the polygon on the canvas, adhering to the current fill state or to the provided params.
  • .wash(color, opacity)
    • Washes the polygon on the canvas with the current wash() state or the provided params.
  • .hatch(distance, angle, options)
    • Applies hatching to the polygon on the canvas, based on the current hatch state or the provided params.
  • .mass()
    • Applies the current mass() state to the polygon.

• Attributes:

  • .vertices: An array of the polygon's vertices, each vertex being an object with x and y properties.
  • .sides: An array representing the different segments that make up the polygon.

---

Class: brush.Plot

• Description: The Plot class is crucial for the plot system, managing a collection of segments to create a variety of shapes and paths. It enables intricate designs, such as curves and custom strokes, by defining each segment with an angle, length, and pressure. Plot instances can be transformed through rotation, and their appearance controlled via pressure and angle calculations.

• Constructor:

  • brush.Plot(_type)
    • _type (String): The type of plot, either "curve" or "segments".

• Methods:

  • .addSegment(_a, _length, _pres)
    • Adds a segment to the plot.
    • Parameters:
      • _a (Number): The angle of the segment.
      • _length (Number): The length of the segment.
      • _pres (Number): The pressure of the segment.
  • .endPlot(_a, _pres)
    • Finalizes the plot with the last angle and pressure.
    • Parameters:
      • _a (Number): The final angle of the plot.
      • _pres (Number): The final pressure of the plot.
  • .rotate(_a)
    • Rotates the entire plot by a specified angle.
    • Parameters:
      • _a (Number): The angle for rotation.
  • .genPol(_x, _y)
    • Generates a polygon based on the plot.
    • Parameters:
      • _x (Number): The x-coordinate for the starting point.
      • _y (Number): The y-coordinate for the starting point.
    • Returns: Polygon - The generated polygon.
  • .draw(x, y)
    • Draws the plot on the canvas with current stroke() state.
    • Parameters:
      • x (Number): The x-coordinate to draw at.
      • y (Number): The y-coordinate to draw at.
  • .fill(x, y)
    • Fills the plot on the canvas with current fill() state.
    • Parameters:
      • x (Number): The x-coordinate to fill at.

---

Class: brush.Position

• Description: The Position class represents a point within a two-dimensional space, capable of interacting with a vector field. It includes methods for updating the position based on the field's flow, allowing for movement through the vector field in various ways.

• Constructor:

  • brush.Position(x, y)
    • x (Number): The initial x-coordinate.
    • y (Number): The initial y-coordinate.

• Methods:

  • .moveTo(_dir, _length, _step_length)
    • Moves the position along the flow field by a specified length.
    • Parameters:
      • _dir (Number): The direction of movement, with angles measured anticlockwise from the x-axis. It is interpreted using the current p5 angleMode().
      • _length (Number): The length to move along the field.
      • _step_length (Number): The length of each step.
  • .plotTo(_plot, _length, _step_length, _scale)
    • Plots a point to another position within the flow field, following a given Plot object.
    • Parameters:
      • _plot (Position): The Plot path object.
      • _length (Number): The length to move towards the target position.
      • _step_length (Number): The length of each step.
      • _scale (Number): The scaling factor for the plotting path.
  • .angle()
    • Returns vector-field angle for that position.
  • .reset()
    • Resets the plotted property to 0. This property tracks the distance moved since the last reset or the creation of the position. Important for consecutive different Plot paths.

• Attributes:

  • .x: The current x-coordinate.
  • .y: The current y-coordinate.
  • .plotted: Stores the distance moved since the last reset or the creation of the position.

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Utility Functions

---

Note for users upgrading from older versions: brush.push(), brush.pop(), brush.translate(), brush.rotate(), and brush.scale() are no longer needed. The library now automatically hooks into p5's push() and pop(), so brush state (stroke, fill, hatch settings) is saved and restored alongside p5's own state. Likewise, p5's translate(), rotate(), and scale() are automatically inherited by all brush strokes and fills.

Public brush APIs that accept angles also inherit p5's current angleMode(). With no angleMode() call, that means radians by default, matching p5 itself. The main exception is brush.addField(name, fn, { angleMode }), which lets custom field generators declare how returned angles should be interpreted before they are stored internally in degrees.

---

Examples

• Basic examples: collection in the p5.js Web Editor (more soon)
• GenArt project 1: Enfantines I
• GenArt project 2: Enfantines II
• GenArt project 3: Fuga a tientas

Contributing

We welcome contributions from the community. If you find a bug or have a feature request, please open an issue on Github.

License

p5.brush.js is released under the MIT License. See the LICENSE file for details.

Acknowledgements

• The fill() operations followed the steps explained by Tyler Hobbs here
• The realistic color blending is calculated with spectral.js, by Ronald van Wijnen
• Several p5 bugs that impacted the library have been found and solved with the help of Dave Pagurek