三个js几何合并矩阵

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 ); 
          ....

我的问题是，为什么在最后一种情况下只应用 makeTranslation(0, 0, 850)，不 makeRotationZ(Math.PI/2)？

如何在合并之前应用两者？

Answer 1

您可以像这样应用两个矩阵：

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