1、语法介绍：与java很相近，可以认为就是java。

2、运行命令（linux）：

processing-java --output=/tmp/processing-xx --run --force --sketch={问存在路径}

3、sketch:

每个sketch（草稿）就是保存在电脑相应文件夹中的，存放有相关processing代码的文件，后缀为：pde以及影音文件（另外存放在data文件夹中）。

4、变量：

1）、区分大小写。

2）、类型包括：整形（int）,浮点型（float）,字符串（String），布尔型（boolean）

5、坐标（Coordinates）：

x轴向右渐增，y轴向右渐增，z轴向外渐增。

// Sets the screen to be 640 pixels wide and 360 pixels high 窗口大小
size(640, 360);

// Set the background to black and turn off the fill color背景颜色
background(0);
noFill();

// The two parameters of the point() method each specify coordinates.
// The first parameter is the x-coordinate and the second is the Y
stroke(255);//画笔颜色
point(width * 0.5, height * 0.5);
point(width * 0.5, height * 0.25);

// Coordinates are used for drawing all shapes, not just points.
// Parameters for different functions are used for different purposes.
// For example, the first two parameters to line() specify
// the coordinates of the first endpoint and the second two parameters
// specify the second endpoint
stroke(0, 153, 255);
line(0, height*0.33, width, height*0.33);

// By default, the first two parameters to rect() are the
// coordinates of the upper-left corner and the second pair
// is the width and height
stroke(255, 153, 0);
rect(width*0.25, height*0.1, width * 0.5, height * 0.8);//矩形

6、判断：

< == > != >=  <=  && || !

7、类：

Object 和 class

8、3D:

pushMatrix();

translate(width/2,height/2);

rotateX(1);

box(150);

popMatrix();

lights();//在draw里面调用即可。

9、循环：

void setup(){
size(600,600);
background(0);

}
void draw(){
for (int i=0;i<20;i++){
for (int j=0;j<20;j++){
if(i<10){
fill(255,0,0);
}else{
fill(255,255,0);
}
ellipse(i*20,j*20,20,20);
}
}
}

10、函数

函数可以写在函数里面：

Ball myBall;
void setup(){
size(600,600);
background(0);
myBall = new Ball(500,100);
}
void draw(){
myBall.display();
}
class Ball{
int x= 500;
int y= 500;
//construct
Ball(int x, int y){
this.x = x;
this.y = y;
}
void display(){
ellipse(x,y,20,20);
}
}

11、Ball bounce and graity 跳跃和重力

//When the shape hits the edge of the window, it reverses its direction.

int rad = 60; // Width of the shape
float xpos, ypos; // Starting position of shape

float xspeed = 2.8; // Speed of the shape
float yspeed = 2.2; // Speed of the shape

int xdirection = 1; // Left or Right
int ydirection = 1; // Top to Bottom

void setup()
{
size(640, 360);
noStroke();
frameRate(30);
ellipseMode(RADIUS);
// Set the starting position of the shape
xpos = width/2;
ypos = height/2;
}

void draw()
{
background(102);

// Update the position of the shape
xpos = xpos + ( xspeed * xdirection );
ypos = ypos + ( yspeed * ydirection );

// Test to see if the shape exceeds the boundaries of the screen
// If it does, reverse its direction by multiplying by -1
if (xpos > width-rad || xpos < rad) { xdirection *= -1; } if (ypos > height-rad || ypos < rad) {
ydirection *= -1;
}

// Draw the shape
ellipse(xpos, ypos, rad, rad);
}

12、数组

myBalls = new Ball[100];
for(int i=0;i<myBalls.length;i++){
myBalls[i] = new Ball(xpos,ypos);
}

13、ArrayList

ArrayList myList;

mylist.add(new Ball(200,200));

mylist.size();

mylist.get(1);

14、声明和注解

// The size function is a statement that tells the computer
// how large to make the window.
// Each function statement has zero or more parameters.
// Parameters are data passed into the function
// and are used as values for telling the computer what to do.
size(640, 360);

// The background function is a statement that tells the computer
// which color (or gray value) to make the background of the display window
background(204, 153, 0);

15、setup & draw

int y = 100;

// The statements in the setup() function
// execute once when the program begins //只执行一次
void setup() {
size(640, 360); // Size must be the first statement
stroke(255); // Set line drawing color to white
frameRate(30); //帧率
}
// The statements in draw() are executed until the
// program is stopped. Each statement is executed in
// sequence and after the last line is read, the first
// line is executed again.//一直执行直到程序停止，每一个变量以队列的方式被读取来执行，直到最后一个，然后又去执行第一个。
void draw() {
background(0); // Clear the screen with a black background
y = y - 1;
if (y < 0) {
y = height;
}
line(0, y, width, y);
}

16、No Loop：让draw()方法只执行一次。

float y;

// The statements in the setup() function
// execute once when the program begins
void setup()
{
size(640, 360); // Size should be the first statement
stroke(255); // Set line drawing color to white
noLoop();

y = height * 0.5;
}

// The statements in draw() are executed until the
// program is stopped. Each statement is executed in
// sequence and after the last line is read, the first
// line is executed again.
void draw()
{
background(0); // Set the background to black
y = y - 1;
if (y < 0) { y = height; }
line(0, y, width, y);
}

17、Loop：让draw()方法持续执行。下面列子：在鼠标点击是让draw（）持续执行：****

float y = 100;

// The statements in the setup() function
// run once when the program begins
void setup() {
size(640, 360); // Size should be the first statement
stroke(255); // Set stroke color to white
noLoop();

y = height * 0.5;
}

// The statements in draw() are run until the
// program is stopped. Each statement is run in
// sequence and after the last line is read, the first
// line is run again.
void draw() {
background(0); // Set the background to black
line(0, y, width, y);

y = y - 1;
if (y < 0) {
y = height;
}
}

void mousePressed() {
loop();
}

18、Redraw：让draw()执行一次。下面列子：当鼠标点击时，执行draw():

float y;

// The statements in the setup() function
// execute once when the program begins
void setup() {
size(640, 360); // Size should be the first statement
stroke(255); // Set line drawing color to white
noLoop();
y = height * 0.5;
}

// The statements in draw() are executed until the
// program is stopped. Each statement is executed in
// sequence and after the last line is read, the first
// line is executed again.
void draw() {
background(0); // Set the background to black
y = y - 4;
if (y < 0) { y = height; }
line(0, y, width, y);
}

void mousePressed() {
redraw();
}

19、方法调用：

void setup() {
size(640, 360);
background(51);
noStroke();
noLoop();
}

void draw() {
drawTarget(width*0.25, height*0.4, 200, 4);
drawTarget(width*0.5, height*0.5, 300, 10);
drawTarget(width*0.75, height*0.3, 120, 6);
}

void drawTarget(float xloc, float yloc, int size, int num) {
float grayvalues = 255/num;
float steps = size/num;
for (int i = 0; i < num; i++) {
fill(i*grayvalues);
ellipse(xloc, yloc, size - i*steps, size - i*steps);
}
}

20、Recursion （递归）：

void setup() {
size(640, 360);
noStroke();
noLoop();
}

void draw() {
drawCircle(width/2, 280, 6);
}

void drawCircle(int x, int radius, int level) {
float tt = 126 * level/4.0;
fill(tt);
ellipse(x, height/2, radius*2, radius*2);
if(level > 1) {
level = level - 1;
drawCircle(x - radius/2, radius/2, level);
drawCircle(x + radius/2, radius/2, level);
}
}

21、Create Graphics.（画图）：

PGraphics pg;

void setup() {
size(640, 360);
pg = createGraphics(400, 200);
}

void draw() {
fill(0, 12);
rect(0, 0, width, height);
fill(255);
noStroke();
ellipse(mouseX, mouseY, 60, 60);

pg.beginDraw();
pg.background(51);
pg.noFill();
pg.stroke(255);
pg.ellipse(mouseX-120, mouseY-60, 60, 60);
pg.endDraw();

// Draw the offscreen buffer to the screen with image()
image(pg, 120, 60);
}