Watertight marching cubes like lookup table?
I'm trying to to polygonise a scalar field. Every point on the grid can only have a value of 1 or 0. I need to create an array with 256 polygon arrays for 8 points, but, unlike marching cubes, the edges of these polygons can only be at the points of the grid.
返回数组的Javascript函数需要gl-matrix.js和vec3.ceil
function () {
var polyConds = [];
var b = function () {
var v = 0;
for (var i = 0; i < arguments.length; i++) {
v |= 1 << (arguments[i] - 1);
}
return v;
};
/* 0 */
polyConds[b()] = [];
/* 1 */
polyConds[b(1)] = [];
/* 2 */
polyConds[b(1, 2)] = [];
polyConds[b(1, 4)] = [];
polyConds[b(1, 8)] = [];
/* 3 */
polyConds[b(1, 2, 3)] = [1, 2, 3];
polyConds[b(1, 2, 7)] = [1, 2, 7, 1, 7, 2];
polyConds[b(1, 4, 6)] = [1, 4, 6, 1, 6, 4];
/* 4 */
polyConds[b(1, 2, 3, 4)] = [1, 2, 3, 2, 4, 3];
polyConds[b(1, 2, 7, 8)] = [1, 2, 7, 7, 8, 2, 1, 7, 2, 7, 2, 8];
polyConds[b(1, 2, 3, 6)] = [1, 6, 3, 2, 3, 6];
polyConds[b(1, 2, 3, 8)] = [1, 2, 3, 2, 3, 8, 2, 8, 3];
polyConds[b(1, 4, 6, 7)] = [1, 4, 7, 1, 7, 4, 1, 4, 6, 1, 6, 4];
polyConds[b(1, 2, 3, 5)] = [2, 3, 5];
polyConds[b(2, 3, 4, 6)] = [2, 6, 3, 3, 6, 4];
/* 5 */
polyConds[b(1, 2, 3, 4, 5)] = [2, 3, 5, 2, 4, 3];
polyConds[b(1, 3, 4, 5, 6)] = [1, 4, 6, 3, 5, 4, 4, 5, 6];
polyConds[b(1, 4, 5, 6, 7)] = [1, 6, 7];
/* 6 */
polyConds[b(1, 2, 3, 4, 5, 6)] = [3, 5, 4, 4, 5, 6];
polyConds[b(1, 2, 4, 5, 6, 7)] = [1, 7, 4, 4, 7, 6];
polyConds[b(2, 3, 4, 5, 6, 7)] = [2, 5, 3, 4, 7, 6];
/* 7 */
polyConds[b(1, 2, 3, 4, 5, 6, 7)] = [4, 7, 6];
/* 8 */
polyConds[b(1, 2, 3, 4, 5, 6, 7, 8)] = [];
for (var k in polyConds) {
var points = [
[0, 0, 0],
[1, 0, 0],
[0, 1, 0],
[1, 1, 0],
[0, 0, 1],
[1, 0, 1],
[0, 1, 1],
[1, 1, 1],
];
polyConds[k] = polyConds[k].map(function (v) {return points[v - 1]});
}
var rotations = [
[
quat.setAxisAngle(quat.create(), vec3.fromValues(1, 0, 0), 0),
quat.setAxisAngle(quat.create(), vec3.fromValues(1, 0, 0), Math.PI/2),
quat.setAxisAngle(quat.create(), vec3.fromValues(1, 0, 0), Math.PI),
quat.setAxisAngle(quat.create(), vec3.fromValues(1, 0, 0), Math.PI/2*3),
quat.setAxisAngle(quat.create(), vec3.fromValues(0, 1, 0), Math.PI/2),
quat.setAxisAngle(quat.create(), vec3.fromValues(0, 1, 0), Math.PI/2*3),
],
[
quat.setAxisAngle(quat.create(), vec3.fromValues(0, 0, 1), 0),
quat.setAxisAngle(quat.create(), vec3.fromValues(0, 0, 1), Math.PI/2),
quat.setAxisAngle(quat.create(), vec3.fromValues(0, 0, 1), Math.PI),
quat.setAxisAngle(quat.create(), vec3.fromValues(0, 0, 1), Math.PI/2*3),
],
];
var unrotations = [
[
quat.setAxisAngle(quat.create(), vec3.fromValues(1, 0, 0), 0),
quat.setAxisAngle(quat.create(), vec3.fromValues(1, 0, 0), -Math.PI/2),
quat.setAxisAngle(quat.create(), vec3.fromValues(1, 0, 0), -Math.PI),
quat.setAxisAngle(quat.create(), vec3.fromValues(1, 0, 0), -Math.PI/2*3),
quat.setAxisAngle(quat.create(), vec3.fromValues(0, 1, 0), -Math.PI/2),
quat.setAxisAngle(quat.create(), vec3.fromValues(0, 1, 0), -Math.PI/2*3),
],
[
quat.setAxisAngle(quat.create(), vec3.fromValues(0, 0, 1), 0),
quat.setAxisAngle(quat.create(), vec3.fromValues(0, 0, 1), -Math.PI/2),
quat.setAxisAngle(quat.create(), vec3.fromValues(0, 0, 1), -Math.PI),
quat.setAxisAngle(quat.create(), vec3.fromValues(0, 0, 1), -Math.PI/2*3),
],
];
for (var i = 0; i < 256; i++)
for (var a = 0, al = rotations[0].length; a < al; a++)
for (var b = 0, bl = rotations[1].length; b < bl; b++) {
var points = [
[0, 0, 0],
[1, 0, 0],
[0, 1, 0],
[1, 1, 0],
[0, 0, 1],
[1, 0, 1],
[0, 1, 1],
[1, 1, 1],
];
var vertices = [];
for (var j = 0; j < 8; j++) {
if (i >> j & 1) {
vertices.push(points[j]);
}
}
for (var j = 0, jl = vertices.length; j < jl; j++) {
var v = vertices[j];
vec3.sub(v, v, vec3.fromValues(0.5, 0.5, 0.5));
vec3.transformQuat(v, v, rotations[0][a]);
vec3.transformQuat(v, v, rotations[1][b]);
vec3.ceil(v, v);
}
var bits = 0;
for (var j = 0, jl = vertices.length; j < jl; j++) {
bits |= 1 << (vertices[j][0] + vertices[j][1] * 2 + vertices[j][2] * 4);
}
if (polyConds[bits]) {
vertices = JSON.parse(JSON.stringify(polyConds[bits]));
for (var j = 0, jl = vertices.length; j < jl; j++) {
var v = vertices[j];
vec3.sub(v, v, vec3.fromValues(0.5, 0.5, 0.5));
vec3.transformQuat(v, v, unrotations[1][b]);
vec3.transformQuat(v, v, unrotations[0][a]);
vec3.ceil(v, v);
}
polyConds[i] = vertices;
a = Infinity; // break to first loop
b = Infinity;
}
}
return polyConds;
}
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