目前，我在三维笛卡尔坐标系中具有顶点的ArrayList。多边形是随机的。它可以是汽车，杯子甚至是龙。
假设密度不变，如何计算此3D对象的质心（x，y，z）？
我将面和顶点存储在ArrayList中。
public ArrayList<stlFace> StlFaces = new ArrayList<stlFace>();
public ArrayList<VertexGeometric> VertexList = new ArrayList<VertexGeometric>();
最佳答案
我使用this来计算与每个面或三角形的质量成比例的表面。为了计算每个三角形的重心和整个对象的重心，我使用了this。我在Face类中添加了辅助方法getCenter（）和getSurface（）来封装仅针对一个面/三角形的计算。
public static class Vertex {
public float x = 0;
public float y = 0;
public float z = 0;
public Vertex(float x, float y, float z) {
this.x = x;
this.y = y;
this.z = z;
}
}
public static class Face {
public Vertex v1;
public Vertex v2;
public Vertex v3;
public Face(Vertex v1, Vertex v2, Vertex v3) {
this.v1 = v1;
this.v2 = v2;
this.v3 = v3;
}
public Vertex getCenter() {
Vertex triangleCenter = new Vertex(0, 0, 0);
triangleCenter.x += v1.x;
triangleCenter.x += v2.x;
triangleCenter.x += v3.x;
triangleCenter.y += v1.y;
triangleCenter.y += v2.y;
triangleCenter.y += v3.y;
triangleCenter.z += v1.z;
triangleCenter.z += v2.z;
triangleCenter.z += v3.z;
triangleCenter.x /= 3;
triangleCenter.y /= 3;
triangleCenter.z /= 3;
return triangleCenter;
}
public float getSurface() {
float x1 = v1.x - v2.x;
float x2 = v1.y - v2.y;
float x3 = v1.z - v2.z;
float y1 = v1.x - v3.x;
float y2 = v1.y - v3.y;
float y3 = v1.z - v3.z;
return (float) Math.sqrt(
Math.pow(x2 * y3 - x3 * y2, 2) +
Math.pow(x3 * y1 - x1 * y3, 2) +
Math.pow(x1 * y2 - x2 * y1, 2)
) / 2f;
}
}
public static Vertex calculateMassCenter(List<Face> faces) {
Vertex massCenter = new Vertex(0, 0, 0);
float mass = 0;
for (Face face : faces) {
Vertex triangleCenter = face.getCenter();
float faceMass = face.getSurface();
mass += faceMass;
massCenter.x += faceMass * triangleCenter.x;
massCenter.y += faceMass * triangleCenter.y;
massCenter.z += faceMass * triangleCenter.z;
}
massCenter.x /= mass;
massCenter.y /= mass;
massCenter.z /= mass;
return massCenter;
}