let tempVertices = [];

let tempVertexNormals = [];

let tempUvs = [];

let tempFaces = [];

​

function setup() {

  createCanvas(400, 400, WEBGL);

  m = createSpike();

  strokeWeight(0.5);

  noStroke();

  fill(250, 170, 0);

}

​

function draw() {

  background(80, 0, 0);

  rotateZ(frameCount * 0.01);

  rotateX(frameCount * 0.01);

  rotateY(frameCount * 0.01);

  ambientLight(140, 140, 0);

  pointLight(255, 255, 0, width/2, -height/2, width);

  scale(.5);

  model(m);

}

​

function createSpike() {

  let detailX = 14;

  let detailY = 15;

  let t = 2 * detailX - 1;

​

  return new p5.Geometry(detailX, detailY, function () {

    // bottomRadius, topRadius, c_height, detailX, offset

    buildGeometry(40, 60, 90, detailX, -200);

    for (let i = 0; i <= t; i++) {

      this.vertices.push(tempVertices[i]);

      this.vertexNormals.push(tempVertexNormals[i]);

    }

​

    buildGeometry(60, 40, 90, detailX, -110);

    for (let i = 0; i <= t; i++) {

      this.vertices.push(tempVertices[i]);

      this.vertexNormals.push(tempVertexNormals[i]);

    }

​

    buildGeometry(40, 60, 90, detailX, -20);

    for (let i = 0; i <= t; i++) {

      this.vertices.push(tempVertices[i]);

      this.vertexNormals.push(tempVertexNormals[i]);

    }

    buildGeometry(60, 100, 70, detailX, 70);

    for (let i = 0; i <= t; i++) {

      this.vertices.push(tempVertices[i]);

      this.vertexNormals.push(tempVertexNormals[i]);

    }

    buildGeometry(100, 180, 100, detailX, 140);

    for (let i = 0; i <= t; i++) {

      this.vertices.push(tempVertices[i]);

      this.vertexNormals.push(tempVertexNormals[i]);

    }

    buildGeometry(180, 150, 30, detailX, 240);

    for (let i = 0; i <= t; i++) {

      this.vertices.push(tempVertices[i]);

      this.vertexNormals.push(tempVertexNormals[i]);

    }

    buildGeometry(150, 120, -30, detailX, 270);

    for (let i = 0; i <= t; i++) {

      this.vertices.push(tempVertices[i]);

      this.vertexNormals.push(tempVertexNormals[i]);

    }

    buildGeometry(120, 0, 50, detailX, 240);

    for (let i = 0; i <= t; i++) {

      this.vertices.push(tempVertices[i]);

      this.vertexNormals.push(tempVertexNormals[i]);

    }

    let startIndex = 0;

    for (let i = 0; i < detailY; i++) {

      for (let j = 0; j < detailX; j++) {

        const nexti = (j + 1) % detailX;

        this.faces.push([startIndex + j, startIndex + nexti, startIndex + detailX + nexti]);

        this.faces.push([startIndex + j, startIndex + detailX + nexti, startIndex + detailX + j]);

      }

      startIndex += detailX;

    }

  });

}

​

function buildGeometry(bottomRadius, topRadius, c_height, detailX, offset){

  tempVertices = [];

  tempVertexNormals = [];

  tempUvs = [];

  slant = atan2(bottomRadius - topRadius, c_height);

  sinSlant = sin(slant);

  cosSlant = cos(slant);

  for (let i = 0; i <= 1; i++) {

    let y = offset + c_height * i;

    if(i == 0) radius = bottomRadius;

    else radius = topRadius;

    for(let j = 0; j < detailX; j++) {

      const ur = TWO_PI * j / (detailX - 1);

      tempVertices.push(new p5.Vector(sin(ur) * radius, y, cos(ur) * radius));

      tempVertexNormals.push(new p5.Vector(sin(ur) * cosSlant, sinSlant, cos(ur) * cosSlant));

    }

  }

}