P語言 Test2

1.使用滑鼠畫出簡單的線條
  line(mouseX, mouseY, pmouseX, pmouseY); //point start and end

2.當滑鼠按下時才畫線
加上判別式 if(mousePressed)
更改背景顏色 background(color)

3.更改筆刷顏色
藉由滑鼠位置判斷選擇顏色進一步更改筆刷顏色
if(mouseX<100 && mouseY<100) {stroke(0,255,0);}
else if(mouseX<100 && mouseY<200){stroke(0,0,255);}
else if(mouseX<100 && mouseY<300){stroke(255,255,0);}

4.更改筆刷大小
當滑鼠移到右邊時，按下滑鼠時，Y愈大，筆刷愈粗
if(mouseX>700) myBrushSize = mouseY/30;

void setup(){
  size(800,600);
  background(255);
  stroke(#FF081C);  //line color
}
float myBrushSize = 1;
color myStroke = color(0);
void draw(){
  stroke(0); strokeWeight(1);
  fill(0,255,0); rect(0,0,100,100);  //pointX,Y,w,h
  fill(0,0,255); rect(0,100,100,100);
  fill(255,255,0); rect(0,200,100,100);
  stroke(myStroke); strokeWeight(myBrushSize);
}
void mouseDragged(){ //mouse move
  line(mouseX, mouseY, pmouseX, pmouseY); //point start and end
}
void mousePressed(){  //mouse down
  if(mouseX<100 && mouseY<100) {myStroke = color(0,255,0);}
  else if(mouseX<100 && mouseY<200){myStroke = color(0,0,255);}
  else if(mouseX<100 && mouseY<300){myStroke = color(255,255,0);}
  if(mouseX>700) myBrushSize = mouseY/30;
}

5.刮畫
版本1    缺點 : 筆刷較大時會發現顏色出現斷層

版本２

PImage imgBG;
PImage imgBlack;
void setup() {
  size(800, 600);
  imgBG = loadImage("color.jpg");
  imgBlack = createImage(800, 600, ARGB);

  imgBlack.loadPixels();
  for (int i = 0; i<imgBlack.pixels.length; i++)
    imgBlack.pixels[i] = color(0, 0, 0, 255);
    imgBlack.updatePixels();
}
void draw() {
  image(imgBG, 0, 0, width, height);
  image(imgBlack, 0, 0, width, height);
}
void mouseDragged() {
  imgBlack.loadPixels();
  imgBlack.pixels[mouseX+mouseY*width] = color(0, 0, 0, 0);
 
  imgBlack.updatePixels();
}

版本 3

PImage imgBG;
PGraphics imgBlack;
void setup() {
  size(800, 600);
  imgBG = loadImage("color.jpg");
  imgBG.resize(800,600);
  imgBlack = createGraphics(800,600);
  imgBlack.beginDraw();
  imgBlack.background(0);
  imgBlack.strokeWeight(5);
  imgBlack.stroke(0,0,0,28);
  imgBlack.endDraw();
}
void draw() {
  background(0);
  imgBG.mask(imgBlack);
  if(keyPressed) image(imgBlack,0,0);
  else image(imgBG,0,0,width,height);
}
void mouseDragged() {
  imgBlack.beginDraw();
  imgBlack.strokeWeight(5);imgBlack.stroke(255);
  imgBlack.line(mouseX,mouseY,pmouseX,pmouseY);
  imgBlack.endDraw();
}