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diff --git a/processing.html.markdown b/processing.html.markdown new file mode 100644 index 00000000..fc5dc997 --- /dev/null +++ b/processing.html.markdown @@ -0,0 +1,421 @@ +--- +language: processing +filename: learnprocessing.pde +contributors: + - ["Phone Thant Ko", "http://github.com/phonethantko"] +--- +## Introduction + +Processing is a programming language for creation of digital arts and multimedia content, allowing non-programmers to +learn fundamentals of computer programming in a visual context. +While the language is based on Java language, +its syntax has been largely influenced by both Java and Javascript syntaxes. [See more here](https://processing.org/reference/) +The language is statically typed, and also comes with its official IDE to compile and run the scripts. + +```processing +/* --------- + Comments + --------- +*/ + +// Single-line comment starts with // + +/* + Since Processing is based on Java, + the syntax for its comments are the same as Java (as you may have noticed above)! + Multi-line comments are wrapped as seen here. +*/ + +/* --------------------------------------- + Writing and Running Processing Programs + --------------------------------------- + */ + +// In Processing, your program's entry point is a function named setup() with a void return type. +// Note! The syntax looks strikingly similar to that of C++. +void setup() { + // This prints out the classic output "Hello World!" to the console when run. + println("Hello World!"); // Another language with a semi-column trap, ain't it? +} + +// Normally, we put all the static codes inside the setup() method as the name suggest since it only runs once. +// It can range from setting the background colours, setting the canvas size. +background(color); // setting the background colour +size(width,height,[renderer]); // setting the canvas size with optional parameter defining renderer +// You will see more of them throughout this document. + +// If you want to run the codes indefinitely, it has to be placed in draw() method. +// draw() must exist if you want the code to run continuously and obviously, there can only be one draw() method. +int i = 0; +void draw() { + // This block of code loops forever until stopped + print(i); + i++; // Increment Operator! +} + +// Now that we know how to write the working script and how to run it, +// we will proceed to explore what data types and collections are supported in Processing. + +/* ------------------------ + Datatypes & collections + ------------------------ +*/ + +// According to Processing References, Processing supports 8 primitive datatypes as follows. + +boolean booleanValue = true; // Boolean +byte byteValueOfA = 23; // Byte +char charValueOfA = 'A'; // Char +color colourValueOfWhiteM = color(255, 255, 255); // Colour (Specified using color() method) +color colourValueOfWhiteH = #FFFFFF; // Colour (Specified using hash value) +int intValue = 5; // Integer (Number without decimals) +long longValue = 2147483648L; // "L" is added to the number to mark it as a long +float floatValue = 1.12345; // Float (32-bit floating-point numbers) +double doubleValue = 1.12345D; // Double (64-bit floating-point numbers) + +// NOTE! +// Although datatypes "long" and "double" work in the language, +// processing functions do not use these datatypes, therefore +// they need to be converted into "int" and "float" datatypes respectively, +// using (int) and (float) syntax before passing into a function. + +// There is a whole bunch of default composite datatypes available for use in Processing. +// Primarily, I will brief through the most commonly used ones to save time. + +// String +// While char datatype uses '', String datatype uses "" - double quotes. +String sampleString = "Hello, Processing!"; +// String can be constructed from an array of char datatypes as well. We will discuss array very soon. +char source = {'H', 'E', 'L', 'L', 'O'}; +String stringFromSource = new String(source); // HELLO +// As in Java, strings can be concatenated using the "+" operator. +print("Hello " + "World!"); // Hello World! + +// Array +// Arrays in Processing can hold any datatypes including Objects themselves. +// Since arrays are similar to objects, they must be created with the keyword "new". +int[] intArray = new int[5]; +int[] intArrayWithValues = {1, 2, 3}; // You can also populate with data. + +// ArrayList +// Functions are similar to those of array; arraylists can hold any datatypes. +// The only difference is arraylists resize dynamically, +// as it is a form of resizable-array implementation of the Java "List" interface. +ArrayList<Integer> intArrayList = new ArrayList<Integer>(); + +// Object +// Since it is based on Java, Processing supports object-oriented programming. +// That means you can basically define any datatypes of your own and manipulate them to your needs. +// Of course, a class has to be defined before for the object you want. +// Format --> ClassName InstanceName +SomeRandomClass myObject // then instantiate later +//or +SomeRandomClass myObjectInstantiated = new SomeRandomClass(); + +// Processing comes up with more collections (eg. - Dictionaries and Lists) by default, +// for the simplicity sake, I will leave them out of discussion here. + +/* ------------ + Maths + ------------ +*/ + +// Arithmetic +1 + 1 // 2 +2 - 1 // 0 +2 * 3 // 6 +3 / 2 // 1 +3.0 / 2 // 1.5 +3.0 % 2 // 1.0 + +// Processing also comes with a set of functions that simplify mathematical operations. +float f = sq(3); // f = 9.0 +float p = pow(3, 3); // p = 27.0 +int a = abs(-13) // a = 13 +int r1 = round(3.1); // r1 = 3 +int r2 = round(3.7); // r2 = 4 +float sr = sqrt(25); // sr = 5.0 + +// Vectors +// Processing provides an easy way to implement vectors in its environment using PVector class. +// It can describe a two or three dimensional vector and +// comes with a set of methods which are useful for matrices operations. +// You can find more information on PVector class and its functions here. +// (https://processing.org/reference/PVector.html) + +// Trigonometry +// Processing also supports trigonometric operations by supplying a set of functions. +// sin(), cos(), tan(), asin(), acos(), atan() and also degrees() and radians() for convenient conversion. +// However, those functions take angle in radians as the parameter so it has to be converted beforehand. +float one = sin(PI/2); // one = 1.0 +// As you may have noticed, there exists a set of constants for trigonometric uses; +// PI, HALF_PI, QUARTER_PI and so on... + +/* ------------- + Control Flow + ------------- +*/ + +// Conditional Statements +// If Statements - The same syntax as if statements in Java. +if (author.getAppearance().equals("hot")) { + print("Narcissism at its best!"); +} else { + // You can check for other conditions here. + print("Something is really wrong here!"); +} +// A shortcut for if-else statements can also be used. +int i = 3; +String value = (i > 5) ? "Big" : "Small"; // "Small" + +// Switch-case structure can be used to check multiple conditions more concisely. +int value = 2; +switch(value) { + case 0: + print("Nought!"); // This doesn't get executed. + break; // Jumps to the next statement + case 1: + print("Getting there..."); // This again doesn't get executed. + break; + case 2: + print("Bravo!"); // This line gets executed. + break; + default: + print("Not found!"); // This line gets executed if our value was some other value. + break; +} + +// Iterative statements +// For Statements - Again, the same syntax as in Java +for(int i = 0; i < 5; i ++){ + print(i); // prints from 0 to 4 +} + +// While Statements - Again, nothing new if you are familiar with Java syntax. +int j = 3; +while(j > 0) { + print(j); + j--; // This is important to prevent from the code running indefinitely. +} + +// loop()| noLoop() | redraw() | exit() +// These are more of Processing-specific functions to configure program flow. +loop(); // allows the draw() method to run forever while +noLoop(); // only allows it to run once. +redraw(); // runs the draw() method once more. +exit(); // This stops the program. It is useful for programs with draw() running continuously. +``` +## Drawing with Processing +Since you will have understood the basics of the language by now, we will now look into the best part of Processing; DRAWING. + +```processing + +/* ------ + Shapes + ------ +*/ + +// 2D Shapes + +// Point +point(x, y); // In 2D space +point(x, y, z); // In 3D space +// Draws a point in the coordinate space. + +// Line +line(x1, y1, x2, y2); // In 2D space +line(x1, y1, z1, x2, y2, z2); // In 3D space +// Draws a line connecting two points defined by (x1, y1) and (x2, y2). + +// Triangle +triangle(x1, y1, x2, y2, x3, y3); +// Draws a triangle connecting three points defined by coordinate paramters. + +// Rectangle +rect(a, b, c, d, [r]); // With optional parameter defining the radius of all corners +rect(a, b, c, d, [tl, tr, br, bl]); // With optional set of parameters defining radius of each corner +// Draws a rectangle with {a, b} as a top left coordinate and c and d as width and height respectively. + +// Quad +quad(x, y, x2, y2, x3, y3, x4, y4); +// Draws a quadrilateral with parameters defining coordinates of each corner point. + +// Ellipse +ellipse(x, y, width, height); +// Draws an eclipse at point {x, y} with width and height specified. + +// Arc +arc(x, y, width, height, start, stop, [mode]); +// While the first four parameters are self-explanatory, +// start and end defined the angles the arc starts and ends (in radians). +// Optional parameter [mode] defines the filling; +// PIE gives pie-like outline, CHORD gives the chord-like outline and OPEN is CHORD without strokes + +// Curves +// Processing provides two implementation of curves; using curve() and bezier(). +// Since I plan to keep this simple I won't be discussing any further details. +// However, if you want to implement it in your sketch, here are the references: +// (https://processing.org/reference/curve_.html)(https://processing.org/reference/bezier_.html) + +// 3D Shapes + +// 3D space can be configured by setting "P3D" to the renderer parameter in size() method. +size(width, height, P3D); +// In 3D space, you will have to translate to the particular coordinate to render the 3D shapes. + +// Box +box(size); // Cube with same length defined by size +box(w, h, d); // Box with width, height and depth separately defined + +// Sphere +sphere(radius); // Its size is defined using the radius parameter +// Mechanism behind rendering spheres is implemented by tessellating triangles. +// That said, how much detail being rendered is controlled by function sphereDetail(res) +// More information here: (https://processing.org/reference/sphereDetail_.html) + +// Irregular Shapes +// What if you wanted to draw something that's not made available by Processing's functions? +// You can use beginShape(), endShape(), vertex(x,y) to define shapes by specifying each point. +// More information here: (https://processing.org/reference/beginShape_.html) +// You can also use custom made shapes using PShape class.(https://processing.org/reference/PShape.html) + +/* --------------- + Transformations + --------------- +*/ + +// Transformations are particularly useful to keep track of the coordinate space +// and the vertices of the shapes you have drawn. +// Particularly, matrix stack methods; pushMatrix(), popMatrix() and translate(x,y) +pushMatrix(); // Saves the current coordinate system to the stack +// ... apply all the transformations here ... +popMatrix(); // Restores the saved coordinate system +// Using them, the coordinate system can be preserved and visualized without causing any conflicts. + +// Translate +translate(x, y); // Translates to point{x, y} i.e. - setting origin to that point +translate(x, y, z); // 3D counterpart of the function + +// Rotate +rotate(angle); // Rotate the amount specified by the angle parameter +// It has 3 3D counterparts to perform rotation, each for every dimension, +// namely: rotateX(angle), rotateY(angle), rotateZ(angle) + +// Scale +scale(s); // Scale the coordinate system by either expanding or contracting it. + +/* -------------------- + Styling and Textures + -------------------- +*/ + +// Colours +// As I have discussed earlier, the background colour can be configured using background() function. +// You can define a color object beforehand and then pass it to the function as an argument. +color c = color(255, 255, 255); // WHITE! +// By default, Processing uses RGB colour scheme but it can be configured to HSB using colorMode(). +// Read here: (https://processing.org/reference/colorMode_.html) +background(color); // By now, the background colour should be white. +// You can use fill() function to select the colour for filling the shapes. +// It has to be configured before you start drawing shapes so the colours gets applied. +fill(color(0, 0, 0)); +// If you just want to colour the outlines of the shapes then you can use stroke() function. +stroke(255, 255, 255, 200); // stroke colour set to yellow with transparency set to a lower value. + +// Images +// Processing can render images and use them in several ways. Mostly stored as PImage datatype. +filter(shader); // Processing supports several filter functions for image manipulation. +texture(image); // PImage can be passed into arguments for texture-mapping the shapes. + +``` +If you want to take things further, there are more things Processing is powered for. Rendering models, shaders and whatnot. +There's too much to cover in a short documentation, so I will leave them out here. Shoud you be interested, please check out the references. +```processing +// Before we move on, I will touch a little bit more on how to import libraries +// so you can extend Processing's functionality to another horizon. + +/* ------- + Imports + ------- +*/ + +// The power of Processing can be further visualized when we import libraries and packages into our sketches. +// Import statement can be written as below at the top of the source code. +import processing.something.*; + +``` +## DTC? + +Down To Code? Let's get our hands dirty! + +Let us see an example from openprocessing to visualize how much Processing is capable of within few lines of code. +Copy the code below into your Processing IDE and see the magic. + +```processing + +// Disclaimer: I did not write this program since I currently am occupied with internship and +// this sketch is adapted from openprocessing since it shows something cool with simple codes. +// Retrieved from: (https://www.openprocessing.org/sketch/559769) + +float theta; +float a; +float col; +float num; + +void setup() { + size(600,600); +} + +void draw() { + background(#F2F2F2); + translate(width/2, height/2); + theta = map(sin(millis()/1000.0), -1, 1, 0, PI/6); + + float num=6; + for (int i=0; i<num; i++) { + a =350; + rotate(TWO_PI/num); + branch(a); + } + +} + + + +void branch(float len) { + col=map(len, 0, 90, 150, 255); + fill(col, 0, 74); + stroke (col, 0, 74); + line(0, 0, 0, -len); + ellipse(0, -len, 3, 3); + len *= 0.7; + + + if (len>30) { + pushMatrix(); + translate(0, -30); + rotate(theta); + branch(len); + popMatrix(); + + pushMatrix(); + translate(0, -30); + rotate(-theta); + branch(len); + popMatrix(); + + } +} + +``` + +Processing is easy to learn and is particularly useful to create multimedia contents (even in 3D) without +having to type a lot of codes. It is so simple that you can read through the code and get a rough idea of +the program flow. +However, that does not apply when you introduce external libraries, packages and even your own classes. +(Trust me! Processing projects can get real humongous...) + +## Some useful resources: + + - [Processing Website](http://processing.org) + - [Processing Sketches](http://openprocessing.org) |