sphericalCoordNotes.txt

Alternate method that ultimately was not easily scalable
Placed here to be referenced in the future to create a UV sphere


icoPosTop.push([0, 1, 0]); // Top     - Index 0

  const psi = Math.PI / 2 - Math.atan(1 / 2);

  for (let i = 0; i < 5; i++) {
    // Circle 2 - Index 1 - 5
    let theta = (2 / 5) * Math.PI * i;
    icoPosTop.push([
      Math.sin(psi) * Math.cos(theta),
      Math.cos(psi),
      Math.sin(psi) * Math.sin(theta),
    ]);
  }


function subdivideIco(icoPosTop) {
  const highPsi = Math.PI / 2 - (Math.PI / 2 + Math.atan(1 / 2)) / 2;
  const sideOffset = Math.PI / 5;

  for (let i = 0; i < 5; i++) {
    // Circle 1 - Index 6 - 10
    let theta = (2 / 5) * Math.PI * i;
    icoPosTop.push([
      Math.sin(highPsi) * Math.cos(theta),
      Math.cos(highPsi),
      Math.sin(highPsi) * Math.sin(theta),
    ]);
  }

  const psi = Math.PI / 2 - Math.atan(1 / 2);

  for (let i = 0; i < 5; i++) {
    // Circle 3 (z=2) - Index 11 - 15
    let theta = (2 / 5) * Math.PI * i + sideOffset;
    icoPosTop.push([
      Math.sin(psi) * Math.cos(theta),
      Math.cos(psi),
      Math.sin(psi) * Math.sin(theta),
    ]);
  }

  const offset = (2 / 20) * Math.PI;
  const middlePsi = Math.PI / 2;

  for (let i = 0; i < 10; i++) {
    // Circle 4  - Index 16 - 25
    let theta = (2 / 10) * Math.PI * i + offset;
    icoPosTop.push([
      Math.sin(middlePsi) * Math.cos(theta),
      Math.cos(middlePsi),
      Math.sin(middlePsi) * Math.sin(theta),
    ]);
  }

  return icoPosTop;
}


  let icoPos = [];
  for (let i = 0; i < icoPosTop.length; i++) {
    icoPos.push(icoPosTop[i]);
    icoPos.push([-icoPosTop[i][0], -icoPosTop[i][1], -icoPosTop[i][2]]);
  }
//console.log(icoPos);


// Generate indices (order to draw verts)
function generateIndices(programInfo, icoPos, subdivisions) {
  // Generate indices to draw faces
  let indices = [];
  const vIndex1 = [2, 4, 6, 8, 10, 2];
  const vIndex2 = [3, 5, 7, 9, 11, 3];
  const vIndex3 = [2, 9, 4, 11, 6, 3, 8, 5, 10, 7, 2, 9];
  for (let i = 0; i < 5; i++) {
    indices.push([0, vIndex1[i], vIndex1[i + 1]]);
    indices.push([1, vIndex2[i], vIndex2[i + 1]]);
    indices.push([vIndex3[i * 2], vIndex3[i * 2 + 1], vIndex3[i * 2 + 2]]);
    indices.push([vIndex3[i * 2 + 1], vIndex3[i * 2 + 2], vIndex3[i * 2 + 3]]);
  }

  const vIndex1 = [12, 14, 16, 18, 20, 12];
  const vIndex2 = [
    2, 12, 22, 4, 14, 24, 6, 16, 26, 8, 18, 28, 10, 20, 30, 2, 12,
  ];
  const vIndex3 = [
    2, 32, 22, 34, 4, 36, 24, 38, 6, 40, 26, 42, 8, 44, 28, 46, 10, 48, 30, 50,
    2, 32,
  ];
  for (let i = 0; i < 5; i++) {
    indices.push([0, vIndex1[i], vIndex1[i + 1]]);
  }
  for (let i = 0; i < 15; i += 3) {
    indices.push([vIndex2[i], vIndex2[i + 2], vIndex2[i + 1]]);
    indices.push([vIndex2[i + 2], vIndex2[i + 4], vIndex2[i + 1]]);
    indices.push([vIndex2[i + 2], vIndex2[i + 3], vIndex2[i + 4]]);
  }
  for (let i = 0; i < 20; i += 2) {
    indices.push([vIndex3[i], vIndex3[i + 1], vIndex3[i + 2]]);
    indices.push([vIndex3[i + 2], vIndex3[i + 1], vIndex3[i + 3]]);
  }

  // Create element (index) buffer
  const eleBuffer = gl.createBuffer();
  gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, eleBuffer);
  gl.bufferData(
    gl.ELEMENT_ARRAY_BUFFER,
    new Int16Array(indices.flat()),
    gl.STATIC_DRAW
  );

  return indices.length;
}