This basic script shows how to get stated with Processing IDE and coding in general. The script offers some key elements like shape drawing, colors, mouse movement, for loops and if cases.
color my_current_color = #000000; // this variable we use variable to save current drawing color color[] my_colors = { #A5E317, #1774E3, #F4F7A0, color(150, 0, 0) }; // my color palette int brush_mode = 0; // our current brush mode // this is run only once at startup void setup() { size(600, 300); // create a new sage window background(255, 204, 0); // fill with organge } // this runs in a loop void draw() { // check if mouse is pressed if (mousePressed) { // if left mousebutton is down if (mouseButton == LEFT) { fill( my_current_color ); // change the fill color noStroke(); for ( int i = 0; i < 10; i++) { float offx = random(-20, 20 ); float offy = random(-20, 20 ); // check // --------------------------------- if(brush_mode == 0){ circle(mouseX + offx, mouseY + offy, 5); // here we draw the circle } // --------------------------------- if(brush_mode == 1){ pushMatrix(); translate(mouseX+offx, mouseY+offy); rotate( random(TWO_PI) ); rect( 0,0, 2,44 ); popMatrix(); } // --------------------------------- if(brush_mode == 2){ strokeWeight(8); // set the stroke thickness stroke(my_current_color ); // set the color of the line line( mouseX+offx,mouseY+offy, width/2, height/2 ); // draw line from point A to point B } } } // if right mousebutton is down if (mouseButton == RIGHT) { // draw a circle with the same color as the background = our cool eraser tool ;) fill(255, 204, 0); circle( mouseX, mouseY, 20); } } filter(POSTERIZE, 4); filter(BLUR, 1); } // this is some keyboard events that are executes on key input void keyPressed() { println(keyCode); if ( keyCode == 83 ) { // 83 is the equivalten of the skey for SAVE saveFrame( "shot_###.png" ); } if ( keyCode == 49 ) { // 49 is the equivalent of 1 key my_current_color = my_colors[0]; // change color to palette color 1 } if ( keyCode == 50 ) { // 50 is the equivalent of 2 key my_current_color = my_colors[1]; // change color to palette color 2 } if ( keyCode == 51 ) { // 50 is the equivalent of 3 key my_current_color = my_colors[2]; // change color to palette color 2 } if ( keyCode == 52 ) { // 50 is the equivalent of 4 key my_current_color = my_colors[3]; // change color to palette color 2 } // change the brushmode with my setup keys // 7 8 9 if ( keyCode == 55 ) { brush_mode = 0;} if ( keyCode == 56 ) { brush_mode = 1;} if ( keyCode == 57 ) { brush_mode = 2;} }