核心思路
将面分为无数个三角面 ,使用向量计算面积
/**
* data [
* [ [x,y,z],[x,y,z],[x,y,z],[x,y,z], ],
* [ [x,y,z],[x,y,z],[x,y,z],[x,y,z], ],
* [ [x,y,z],[x,y,z],[x,y,z],[x,y,z], ],
* .......
* ]
*/
// 计算表面积
const calculateFaceArea = (data) => {
let area = 0
let max_i = data.length
let max_j = data[0].length
for (let i = 1; i < max_i; i++) {
for (let j = 1; j < max_j; j++) {
let p = data[i][j]
let p1 = data[i][j - 1]
let p2 = data[i - 1][j - 1]
let p3 = data[i - 1][j]
if (p && p1 && p2) {
let a1 = getTriangleArea(...p, ...p1, ...p2)
area += a1
}
if (p && p2 && p3) {
let a1 = getTriangleArea(...p, ...p2, ...p3)
area += a1
}
}
}
return area
}
// 计算三角面面积
const getTriangleArea = (x1, y1, z1, x2, y2, z2, x3, y3, z3) => {
var v1 = [x1 - x2, y1 - y2, z1 - z2];
var v2 = [x1 - x3, y1 - y3, z1 - z3];
var crossProduct = [
v1[1] * v2[2] - v1[2] * v2[1],
v1[2] * v2[0] - v1[0] * v2[2],
v1[0] * v2[1] - v1[1] * v2[0]
];
var area = 0.5 * Math.sqrt(
crossProduct[0] * crossProduct[0] +
crossProduct[1] * crossProduct[1] +
crossProduct[2] * crossProduct[2]
);
return area;
}