# 円から四角に変形するオブジェクト

```/**
* morphing between circle and square
*
* @author aa_debdeb
* @date 2016/12/03
*/

int pointNum = 1000;
PVector[] circlePoints;
PVector[] rectPoints;
float shapeRate = 0.0;
float shapeRateSpeed = -0.005;
color circleColor = color(0, 237, 217);
color rectColor = color(217, 0, 237);

void setup(){
size(640, 640);
noFill();
strokeWeight(20);
circlePoints = new PVector[pointNum];
for(int i = 0; i < pointNum; i++){
float angle = TWO_PI / pointNum * i;
}
rectPoints = new PVector[pointNum];
PVector[] vertices = {new PVector(radius, 0),
for(int i = 0; i < pointNum; i++){
int vi = int((float(i) / pointNum) * 4);
int vj = vi != 3 ? vi + 1: 0;
float rate = (i - (pointNum / 4.0 * vi)) / (pointNum / 4.0);
float x = lerp(vertices[vi].x, vertices[vj].x, rate);
float y = lerp(vertices[vi].y, vertices[vj].y, rate);
rectPoints[i] = new PVector(x, y);
}
}

void draw(){
background(255, 242, 200);
translate(width / 2, height / 2);
rotate(frameCount * 0.01);
float v = mapToQuart(shapeRate);
stroke(lerpColor(circleColor, rectColor, v));
beginShape();
for(int i = 0; i < pointNum; i++){
float x = lerp(circlePoints[i].x, rectPoints[i].x, v);
float y = lerp(circlePoints[i].y, rectPoints[i].y, v);
vertex(x, y);
}
endShape(CLOSE);
shapeRate = constrain(shapeRate + shapeRateSpeed, 0, 1);
}

float mapToQuart(float v){
if(v < 0.5){
return 8 * v * v * v * v;
} else {
return -8.0 * (v - 1.0) * (v - 1.0) * (v - 1.0) * (v - 1.0) + 1.0;
}
}

void mousePressed(){
shapeRateSpeed *= -1;
}
```