p5

README

p5

p5 is a simple package that provides primitives resembling the ones exposed by the p5/processing library.

License

p5 is released under the BSD-3 license.

Documentation

Documentation for p5 is served by GoDev.

Contributing

Guidelines for contributing to go-p5 the same than for the Go project.

Installation

This project relies on Gio for the graphics parts. As Gio uses system libraries to display graphics, you need to install those for your system/OS for p5 to work properly. See Gio/install for details.

Example

package main

import (
	"image/color"
	"math"

	"github.com/go-p5/p5"
)

func main() {
	p5.Run(setup, draw)
}

func setup() {
	p5.Canvas(400, 400)
	p5.Background(color.Gray{Y: 220})
}

func draw() {
	p5.StrokeWidth(2)
	p5.Fill(color.RGBA{R: 255, A: 208})
	p5.Ellipse(50, 50, 80, 80)

	p5.Fill(color.RGBA{B: 255, A: 208})
	p5.Quad(50, 50, 80, 50, 80, 120, 60, 120)

	p5.Fill(color.RGBA{G: 255, A: 208})
	p5.Rect(200, 200, 50, 100)

	p5.Fill(color.RGBA{G: 255, A: 208})
	p5.Triangle(100, 100, 120, 120, 80, 120)

	p5.TextSize(24)
	p5.Text("Hello, World!", 10, 300)

	p5.Stroke(color.Black)
	p5.StrokeWidth(5)
	p5.Arc(300, 100, 80, 20, 0, 1.5*math.Pi)
}

Documentation

Overview

Package p5 provides types and functions to draw geometrical shapes on a canvas, interact with the mouse and keyboard, with the aim to learn programming with a graphics aid.

p5 is inspired by Processing and its p5js port:

• https://processing.org
• https://p5js.org

A very simple p5 program could look like:

func main() {
    p5.Run(setup, draw)
}

func setup() {
    p5.Canvas(200, 200)
    p5.Background(color.Black)
}

func draw() {
    p5.Fill(color.White)
    p5.Square(10, 10, 50, 50)
}

p5 actually provides two set of APIs:

• one closely following the p5js API, with global functions and hidden state,
• another one based on the p5.Proc type that encapsulates state.

Index

• Variables
• func Arc(x, y, w, h float64, beg, end float64)
• func Background(c color.Color)
• func Canvas(w, h int)
• func Circle(x, y, d float64)
• func Ellipse(x, y, w, h float64)
• func Fill(c color.Color)
• func Line(x1, y1, x2, y2 float64)
• func Quad(x1, y1, x2, y2, x3, y3, x4, y4 float64)
• func Rect(x, y, w, h float64)
• func Run(setup, draw Func)
• func Screenshot(fname string)
• func Square(x, y, s float64)
• func Stroke(c color.Color)
• func StrokeWidth(v float64)
• func Text(txt string, x, y float64)
• func TextSize(size float64)
• func Triangle(x1, y1, x2, y2, x3, y3 float64)
• type Buttons
  • func (b Buttons) Contain(buttons Buttons) bool
• type Func
• type Proc
  • func (p *Proc) Arc(x, y, w, h float64, beg, end float64)
  • func (p *Proc) Background(c color.Color)
  • func (p *Proc) Canvas(w, h int)
  • func (p *Proc) Circle(x, y, d float64)
  • func (p *Proc) Ellipse(x, y, w, h float64)
  • func (p *Proc) Fill(c color.Color)
  • func (p *Proc) Line(x1, y1, x2, y2 float64)
  • func (p *Proc) Quad(x1, y1, x2, y2, x3, y3, x4, y4 float64)
  • func (p *Proc) Rect(x, y, w, h float64)
  • func (p *Proc) Run()
  • func (p *Proc) Screenshot(fname string) error
  • func (p *Proc) Square(x, y, s float64)
  • func (p *Proc) Stroke(c color.Color)
  • func (p *Proc) StrokeWidth(v float64)
  • func (p *Proc) Text(txt string, x, y float64)
  • func (p *Proc) TextSize(size float64)
  • func (p *Proc) Triangle(x1, y1, x2, y2, x3, y3 float64)

Variables

var Event struct {
	Mouse struct {
		Pressed      bool
		PrevPosition struct {
			X float64
			Y float64
		}
		Position struct {
			X float64
			Y float64
		}
		Buttons Buttons
	}
}

Event is the current event pushed from the system.

Functions

func Arc

func Arc(x, y, w, h float64, beg, end float64)

Arc draws an ellipsoidal arc centered at (x,y), with the provided width and height, and a path from the beg to end radians. Positive angles denote a counter-clockwise path.

func Background

func Background(c color.Color)

Background defines the background color for the painting area. The default color is transparent.

func Canvas

func Canvas(w, h int)

Canvas defines the dimensions of the painting area, in pixels.

func Circle

func Circle(x, y, d float64)

Circle draws a circle at (x,y) with a diameter d.

func Ellipse

func Ellipse(x, y, w, h float64)

Ellipse draws an ellipse at (x,y) with the provided width and height.

func Fill

func Fill(c color.Color)

Fill sets the color used to fill shapes.

func Line

func Line(x1, y1, x2, y2 float64)

Line draws a line between (x1,y1) and (x2,y2).

func Quad

func Quad(x1, y1, x2, y2, x3, y3, x4, y4 float64)

Quad draws a quadrilateral, connecting the 4 points (x1,y1), (x2,y2), (x3,y3) and (x4,y4) together.

func Rect

func Rect(x, y, w, h float64)

Rect draws a rectangle at (x,y) with width w and height h.

func Run

func Run(setup, draw Func)

Run executes the user functions setup and draw. Run never exits.

func Screenshot

func Screenshot(fname string)

Screenshot saves the current canvas to the provided file. Supported file formats are: PNG, JPEG and GIF.

func Square

func Square(x, y, s float64)

Square draws a square at (x,y) with size s.

func Stroke

func Stroke(c color.Color)

Stroke sets the color of the strokes.

func StrokeWidth

func StrokeWidth(v float64)

StrokeWidth sets the size of the strokes.

func Text

func Text(txt string, x, y float64)

Text draws txt on the screen at (x,y).

func TextSize

func TextSize(size float64)

TextSize sets the text size.

func Triangle

func Triangle(x1, y1, x2, y2, x3, y3 float64)

Triangle draws a triangle, connecting the 3 points (x1,y1), (x2,y2) and (x3,y3) together.

Types

type Buttons

type Buttons uint8

Buttons is a set of mouse buttons.

const (
	ButtonLeft Buttons = 1 << iota
	ButtonRight
	ButtonMiddle
)

func (Buttons) Contain

func (b Buttons) Contain(buttons Buttons) bool

Contain reports whether the set b contains all of the buttons.

type Func

type Func func()

Func is the type of functions users provide to p5.

type Proc

type Proc struct {
	Setup Func
	Draw  Func
	Mouse Func
	// contains filtered or unexported fields
}

Proc is a p5 processor.

Proc runs the bound Setup function once before the event loop. Proc then runs the bound Draw function once per event loop iteration.

func (*Proc) Arc

func (p *Proc) Arc(x, y, w, h float64, beg, end float64)

Arc draws an ellipsoidal arc centered at (x,y), with the provided width and height, and a path from the beg to end radians. Positive angles denote a counter-clockwise path.

func (*Proc) Background

func (p *Proc) Background(c color.Color)

Background defines the background color for the painting area. The default color is transparent.

func (*Proc) Canvas

func (p *Proc) Canvas(w, h int)

Canvas defines the dimensions of the painting area, in pixels.

func (*Proc) Circle

func (p *Proc) Circle(x, y, d float64)

Circle draws a circle at (x,y) with a diameter d.

func (*Proc) Ellipse

func (p *Proc) Ellipse(x, y, w, h float64)

Ellipse draws an ellipse at (x,y) with the provided width and height.

func (*Proc) Fill

func (p *Proc) Fill(c color.Color)

Fill sets the color used to fill shapes.

func (*Proc) Line

func (p *Proc) Line(x1, y1, x2, y2 float64)

Line draws a line between (x1,y1) and (x2,y2).

func (*Proc) Quad

func (p *Proc) Quad(x1, y1, x2, y2, x3, y3, x4, y4 float64)

Quad draws a quadrilateral, connecting the 4 points (x1,y1), (x2,y2), (x3,y3) and (x4,y4) together.

func (*Proc) Rect

func (p *Proc) Rect(x, y, w, h float64)

Rect draws a rectangle at (x,y) with width w and height h.

func (*Proc) Run

func (p *Proc) Run()

func (*Proc) Screenshot

func (p *Proc) Screenshot(fname string) error

Screenshot saves the current canvas to the provided file. Supported file formats are: PNG, JPEG and GIF.

func (*Proc) Square

func (p *Proc) Square(x, y, s float64)

Square draws a square at (x,y) with size s.

func (*Proc) Stroke

func (p *Proc) Stroke(c color.Color)

Stroke sets the color of the strokes.

func (*Proc) StrokeWidth

func (p *Proc) StrokeWidth(v float64)

StrokeWidth sets the size of the strokes.

func (*Proc) Text

func (p *Proc) Text(txt string, x, y float64)

Text draws txt on the screen at (x,y).

func (*Proc) TextSize

func (p *Proc) TextSize(size float64)

TextSize sets the text size.

func (*Proc) Triangle

func (p *Proc) Triangle(x1, y1, x2, y2, x3, y3 float64)

Triangle draws a triangle, connecting the 3 points (x1,y1), (x2,y2) and (x3,y3) together.