@davepagurek/p5.buildgeometry v0.0.6

p5.buildGeometry

Create a reusable p5.Geometry using the 3D primitives you're familiar with from p5!

Why?

P5's WebGL mode uses the GPU, and the GPU is fast! However, sending data back and forth between the CPU and GPU can slow your sketch down a lot. If you have a shape that won't change from frame to frame, you can create a p5.Geometry, which you draw with model(yourGeometry), to avoid sending the same model data to the GPU every frame.

Unfortunately, p5 on its own doesn't have any easy way to make a p5.Geometry other than manually placing vertices. This library lets you build one out of all the p5 functions you already know: 3D primitives, rotate()/translate()/scale(), push()/pop(), beginShape()/vertex()/endShape(), etc!

Get the library

Add the library to your source code, after loading p5 but before loading your own code.

Via CDN

<script src="https://cdn.jsdelivr.net/npm/@davepagurek/p5.buildgeometry@0.0.6/build/p5.buildGeometry.js"></script>

Self-hosted

Download the minified or unminified source code from the releases tab, then add it to your HTML:

<script type="text/javascript" src="p5.buildGeometry.js"></script>

Via Typescript

First add the dependency:

yarn add @davepagurek/p5.buildgeometry

Yes, that's right, the dependency is named @davepagurek/p5.buildgeometry (all lowercase) even though the function name and repo name are p5.buildGeometry (with a capital G.) NPM doesn't like uppercase letters in packages 🥲

import '@davepagurek/p5.buildgeometry'

Usage

Create geometry in setup by calling buildgeometry. You need to pass in a unique id for your geometry, and a function that constructs the shape.

const myGeom = buildGeometry('myGeom', (builder) => {
  builder.push()
  builder.translate(100, -50)
  builder.scale(0.5)
  builder.rotateX(PI/4)
  builder.cone()
  builder.pop()
  builder.cone()
})

Inside of your callback, you can use the methods you'd normally use on a p5.Graphics to draw shapes.

Then, you can draw your geometry to the screen as if it was an imported model:

model(myGeom)

If you want to free your geometry from memory (allowing you to reassign its ID), call freeGeometry on it:

// If you were drawing it to the main canvas
freeGeometry(myGeom)

// If you were drawing it to a graphic:
myGraphic.freeGeometry(myGeom)

If you want to write a shader that uses the builder's vertex colors, just make sure it has an attribute vec4 aVertexColor and p5 will send the colors to your shader. For convenience, there are two shader helpers that make use of the colors that mimic p5's standard shaders:

// For full lighting (make sure you set up lights too):
shadedModelColors()

// For flat colors:
flatModelColors()

Examples

A branching tree

let tree
let button

function setup() {
  createCanvas(600, 600, WEBGL)
  button = createButton('Regenerate')
  button.mousePressed(makeTree)
  makeTree()
}

function makeTree() {
  if (tree) freeGeometry(tree)

  tree = buildGeometry('tree', (builder) => {
    const addBranch = (depth) => {
      builder.push()
      builder.translate(0, -50)
      builder.cylinder(15, 100)
      builder.translate(0, -50)
      if (depth >= 5) {
        builder.sphere(30)
      } else {
        const numChildren = round(random(1, 3))
        for (let i = 0; i < numChildren; i++) {
          builder.push()
          builder.rotateZ(random(-0.3, 0.3) * PI)
          builder.rotateY(random(TWO_PI))
          addBranch(depth + 1)
          builder.pop()
        }
      }
      builder.pop()
    }
    builder.translate(0, 200)
    builder.scale(0.7)
    addBranch(0)
  })
}

function draw() {
  background(255)
  lights()
  noStroke()
  ambientMaterial(255)
  orbitControl()
  model(tree)
}

View live

Using vertex colors

let tree
let button

function setup() {
  createCanvas(600, 600, WEBGL)
  button = createButton('Regenerate')
  button.mousePressed(makeTree)
  makeTree()
}

function makeTree() {
  if (tree) freeGeometry(tree)

  tree = buildGeometry('tree', (builder) => {
    const addBranch = (depth) => {
      builder.push()
      builder.translate(0, -50)
      builder.fill('#857259')
      builder.cylinder(15, 100)
      builder.translate(0, -50)
      if (depth >= 5) {
        builder.fill('#8ae887')
        builder.sphere(30)
      } else {
        const numChildren = round(random(1, 3))
        for (let i = 0; i < numChildren; i++) {
          builder.push()
          builder.rotateZ(random(-0.3, 0.3) * PI)
          builder.rotateY(random(TWO_PI))
          addBranch(depth + 1)
          builder.pop()
        }
      }
      builder.pop()
    }
    builder.translate(0, 200)
    builder.scale(0.7)
    addBranch(0)
  })
}

function draw() {
  background(255)
  orbitControl()
  push()
  noStroke()
  if (millis() % 2000 < 1000) {
    lights()
    ambientMaterial(255)
    shadedModelColors()
  } else {
    flatModelColors()
  }
  model(tree)
  pop()
}

Flat:

Shaded:

View live

Supported methods

• Adding geometry
  • model()
  • beginShape()
  • endShape()
  • vertex()
  • bezierVertex()
  • quadraticVertex()
  • curveVertex()
  • curveTightness()
  • normal()
  • fill() (to set vertex colors)
  • plane()
  • box()
  • sphere()
  • cylinder
  • cone()
  • torus()
  • triangle()
  • circle()
  • ellipse()
  • arc()
  • rectMode()
  • rect()
  • quad()
  • bezier()
  • curve()
  • line()
• Updating transforms
  • push()
  • pop()
  • translate()
  • scale()
  • rotate()
  • rotateX()
  • rotateY()
  • rotateZ()
  • applyMatrix()
  • resetMatrix()