LatheGeometry constructor
LatheGeometry(
- dynamic points, {
- dynamic segments = 12,
- dynamic phiStart = 0,
- double phiLength = Math.PI * 2,
Implementation
LatheGeometry(points,
{segments = 12, phiStart = 0, double phiLength = Math.PI * 2})
: super() {
parameters = {
"points": points,
"segments": segments,
"phiStart": phiStart,
"phiLength": phiLength
};
segments = Math.floor(segments);
// clamp phiLength so it's in range of [ 0, 2PI ]
phiLength = MathUtils.clamp(phiLength, 0, Math.PI * 2);
// buffers
var indices = [];
List<double> vertices = [];
List<double> uvs = [];
var initNormals = [];
List<double> normals = [];
// helper variables
var inverseSegments = 1.0 / segments;
var vertex = Vector3();
var uv = Vector2(null, null);
var normal = Vector3();
var curNormal = Vector3();
var prevNormal = Vector3();
double dx = 0;
double dy = 0;
// pre-compute normals for initial "meridian"
for (var j = 0; j <= (points.length - 1); j++) {
// special handling for 1st vertex on path
if (j == 0) {
dx = points[j + 1].x - points[j].x;
dy = points[j + 1].y - points[j].y;
normal.x = dy * 1.0;
normal.y = -dx;
normal.z = dy * 0.0;
prevNormal.copy(normal);
normal.normalize();
initNormals.addAll([normal.x, normal.y, normal.z]);
} else if (j == points.length - 1) {
// special handling for last Vertex on path
initNormals.addAll([prevNormal.x, prevNormal.y, prevNormal.z]);
} else {
// default handling for all vertices in between
dx = points[j + 1].x - points[j].x;
dy = points[j + 1].y - points[j].y;
normal.x = dy * 1.0;
normal.y = -dx;
normal.z = dy * 0.0;
curNormal.copy(normal);
normal.x += prevNormal.x;
normal.y += prevNormal.y;
normal.z += prevNormal.z;
normal.normalize();
initNormals.addAll([normal.x, normal.y, normal.z]);
prevNormal.copy(curNormal);
}
}
// generate vertices, uvs and normals
// generate vertices and uvs
for (var i = 0; i <= segments; i++) {
var phi = phiStart + i * inverseSegments * phiLength;
var sin = Math.sin(phi);
var cos = Math.cos(phi);
for (var j = 0; j <= (points.length - 1); j++) {
// vertex
vertex.x = points[j].x * sin;
vertex.y = points[j].y;
vertex.z = points[j].x * cos;
vertices.addAll(
[vertex.x.toDouble(), vertex.y.toDouble(), vertex.z.toDouble()]);
// uv
uv.x = i / segments;
uv.y = j / (points.length - 1);
uvs.addAll([uv.x.toDouble(), uv.y.toDouble()]);
// normal
var x = initNormals[3 * j + 0] * sin;
var y = initNormals[3 * j + 1];
var z = initNormals[3 * j + 0] * cos;
normals.addAll([x, y, z]);
}
}
// indices
for (var i = 0; i < segments; i++) {
for (var j = 0; j < (points.length - 1); j++) {
var base = j + i * points.length;
var a = base;
var b = base + points.length;
var c = base + points.length + 1;
var d = base + 1;
// faces
indices.addAll([a, b, d]);
indices.addAll([c, d, b]);
}
}
// build geometry
setIndex(indices);
setAttribute('position',
Float32BufferAttribute(Float32Array.from(vertices), 3, false));
setAttribute(
'uv', Float32BufferAttribute(Float32Array.from(uvs), 2, false));
setAttribute('normal',
Float32BufferAttribute(Float32Array.from(normals), 3, false));
}