3 JS幾何合併矩陣

Question

  var ShipGeometry = new THREE.Geometry(); 

      var ShipModule1geo = new THREE.SphereGeometry(150.0, 40, 30); 
       ShipGeometry.merge(ShipModule1geo); // this works 

      var ShipModule2geo = new THREE.BoxGeometry(5.0, 5.0, 600, 1, 1, 1); 
      var matrix = new THREE.Matrix4().makeTranslation(0,0,450); 
       ShipGeometry.merge(ShipModule2geo,matrix); // this works too 

      var ShipModule3geo = new THREE.CylinderGeometry(150, 150, 20, 32); 
      var matrix = new THREE.Matrix4().makeTranslation(0, 0, 850).makeRotationZ(Math.PI/2); 
       ShipGeometry.merge(ShipModule3geo,matrix); // only rotation is applyed 

      shipMesh = new THREE.Mesh(ShipGeometry, ShipMaterial); 
      .... 

我的問題，爲什麼applyed 只makeTranslation(0, 0, 850)，不makeRotationZ(Math.PI/2)在最後一種情況？

如何合併前合併？

Answer 1

您可以將兩個矩陣是這樣的：

var matrix = new THREE.Matrix4(); 
matrix.multiply(new THREE.Matrix4().makeTranslation(0, 0, 850)); 
matrix.multiply(new THREE.Matrix4().makeRotationZ(Math.PI/2));