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9 years ago Jsc3d itself hasn't got any function to do this because it mainly aims at
visualization. But it's not difficult to write one since the vertex and the
face data are available in the mesh objects. I have implemented this method
for someone years before. It may also be of some use for you.
The following method compute the volume of a single mesh:
function computeVolume(mesh) {
var sum = 0;
var ibuf = mesh.indexBuffer;
var vbuf = mesh.vertexBuffer;
var i = 0, j = 0;
// walk through all faces, calculating the volume of the mesh
while(i < mesh.faceCount) {
var v0, v1, v2;
var x0, y0, z0, x1, y1, z1, x2, y2, z2;
v0 = ibuf[j++] * 3;
v1 = ibuf[j++] * 3;
// calculate volume of the polyhedron formed by the origin point and this face
do {
v2 = ibuf[j++] * 3;
x0 = vbuf[v0 ];
y0 = vbuf[v0 + 1];
z0 = vbuf[v0 + 2];
x1 = vbuf[v1 ];
y1 = vbuf[v1 + 1];
z1 = vbuf[v1 + 2];
x2 = vbuf[v2 ];
y2 = vbuf[v2 + 1];
z2 = vbuf[v2 + 2];
sum += - x2 * y1 * z0
+ x1 * y2 * z0
+ x2 * y0 * z1
- x0 * y2 * z1
- x1 * y0 * z2
+ x0 * y1 * z2;
v1 = v2;
} while (ibuf[j] != -1);
// continue to next face
j++;
i++;
}
return Math.abs(sum/6);
}
It can be used like this:
// say we are to compute the volume of the first mesh after the model is loaded completely
var mesh = viewer.getScene().getChildren()[0];
var volume = computeVolume(mesh);
console.info('the volume is ' + volume);
If you just want the total volume of all meshes all over a model, then compute
it like this:
// compute the total volume of a model after it has been loaded completely
var totalVolume = 0;
viewer.getScene().forEachChild( function(mesh) {
totalVolume += computeVolume(mesh);
} );
console.info('the total volume is: ' + totalVolume);
The algorithm is based on the assumption that all the meshes are closed.
Otherwise, the result is undefined.Original comment by Humu2...@gmail.com on 10 Sep 2014 at 2:30
Original issue reported on code.google.com by
max.lyap...@gmail.comon 9 Sep 2014 at 4:58