三个js定义几何轴 [英] Three js define axis of the geomatry

问题描述

我有一个盒子几何体，

我想定义几何体的前面在哪里，设置一个框:

I want to define where is the front of my geometry, setting a box:

var materialArray = [];
    materialArray.push(new THREE.MeshBasicMaterial( { map: THREE.ImageUtils.loadTexture( 'test/Three.js/images/xpos.png' ) }));
    materialArray.push(new THREE.MeshBasicMaterial( { map: THREE.ImageUtils.loadTexture( 'test/Three.js/images/xneg.png' ) }));
    materialArray.push(new THREE.MeshBasicMaterial( { map: THREE.ImageUtils.loadTexture( 'test/Three.js/images/ypos.png' ) }));
    materialArray.push(new THREE.MeshBasicMaterial( { map: THREE.ImageUtils.loadTexture( 'test/Three.js/images/yneg.png' ) }));
    materialArray.push(new THREE.MeshBasicMaterial( { map: THREE.ImageUtils.loadTexture( 'test/Three.js/images/zpos.png' ) }));
    materialArray.push(new THREE.MeshBasicMaterial( { map: THREE.ImageUtils.loadTexture( 'test/Three.js/images/zneg.png' ) }));
    var MovingCubeMat = new THREE.MeshFaceMaterial(materialArray);
    var MovingCubeGeom = new THREE.BoxGeometry( 100*meter, 50*meter, 300*meter, 1, 1, 1, materialArray );
    myMesh = new THREE.Mesh( MovingCubeGeom, MovingCubeMat );       
    scene.add( myMesh );    

当我使用 myMesh.lookAt(myTarget) 瞄准目标时，带有纹理zneg.png"(应该是物体的正面)的一侧在背面，物体是定向的通过zpos.png"面向目标的一面.

When i use myMesh.lookAt(myTarget) for aiming a target, side with texture "zneg.png" (which should be a front of object) is on the back side, object is oriented by "zpos.png" side facing to the target.

如何定义对象的正面和底部，或顶部和背面，以便简单地使用旋转?

How can i define front and bottom, or top and back side of my object, for simple using rotations?

谢谢.

推荐答案

当一个对象处于其默认方向时，它被认为是在看其内部的正 z 轴的方向.(相机是个例外，它正朝着其内部负 z 轴的方向看.)

When an object is in its default orientation, it is considered to be looking in the direction of its internal, positive z-axis. (The exception is the camera, which is looking in the direction of its internal negative z-axis.)

当你调用 object.lookAt( target ) 时，对象被旋转，所以它的内部 z 轴指向目标的方向.

When you call object.lookAt( target ), the the object is rotated so its internal z-axis points in the direction of the target.

如果您希望几何体的另一侧面向内部正 z 轴，请在创建几何体后立即对其应用变换.

If you want a different side of your geometry to face the internal positive z-axis, apply a transform to your geometry right after you create it.

geometry.applyMatrix( new THREE.Matrix4().makeRotation( 0, Math.PI, 0 ) );

您还可以使用其中一种内置方法.例如，

You can also use one of the built-in methods. For example,

geometry.rotateY( Math.PI );

three.js r.100

three.js r.100

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