Function makeSphere

examples/pbr-spheres/main.ts:133–170

(segs: number, rings: number)

// `new Array(N)` + index assignment is documented as working
// (per the perry-llvm fix history).
function makeSphere(segs: number, rings: number): {
  vertices: number[]; vertexCount: number;
  indices: number[];  indexCount: number;
} {
  const vCount = (rings + 1) * (segs + 1);
  const iCount = rings * segs * 6;
  const verts: number[] = new Array(vCount * 12);
  const inds:  number[] = new Array(iCount);
  let vi = 0;
  for (let r = 0; r <= rings; r = r + 1) {
    const phi = PI * r / rings;
    const sp = Math.sin(phi);
    const cp = Math.cos(phi);
    for (let s = 0; s <= segs; s = s + 1) {
      const theta = TWO_PI * s / segs;
      const x = sp * Math.cos(theta);
      const y = cp;
      const z = sp * Math.sin(theta);
      verts[vi]      = x; verts[vi + 1]  = y; verts[vi + 2]  = z;       // pos
      verts[vi + 3]  = x; verts[vi + 4]  = y; verts[vi + 5]  = z;       // normal
      verts[vi + 6]  = 1; verts[vi + 7]  = 1; verts[vi + 8]  = 1;
      verts[vi + 9]  = 1;                                                // color rgba
      verts[vi + 10] = s / segs; verts[vi + 11] = r / rings;             // uv
      vi = vi + 12;
    }
  }
  let ii = 0;
  for (let r = 0; r < rings; r = r + 1) {
    for (let s = 0; s < segs; s = s + 1) {
      const a = r * (segs + 1) + s;
      const b = a + segs + 1;
      inds[ii]     = a; inds[ii + 1] = b; inds[ii + 2] = a + 1;
      inds[ii + 3] = b; inds[ii + 4] = b + 1; inds[ii + 5] = a + 1;
      ii = ii + 6;
    }
  }
  return { vertices: verts, vertexCount: vCount, indices: inds, indexCount: iCount };
}

function initSharedMeshes(): void {
  const sphere = makeSphere(24, 16);