如何用相机角度移动相机？

Question

I made a simple threeJS 3d app in which you can look around and move with 4 keys. The problem is that it moves in the same direction no matter where you look to, obviously because I use:

camera.position.x += 0.1

Answer 1

You have to set the default displacement of (0.1, 0, 0) to a Vector3, then apply the camera's rotation (its quaternion) to that vector before adding it to its position. See the code below:

// Create camera
var camera = new THREE.PerspectiveCamera();

// Create displacement vector to re-use
var dispVector = new THREE.Vector3();

function onRightKey() {
    dispVector.set(0.1, 0, 0); // Right key moves 0.1 on x axis
    applyDisplacement();
}

function applyDisplacement() {
    // We apply the camera's rotation to the displacement vector
    dispVector.applyQuaternion(camera.quaternion);

    // Move the camera position by the resulting displacement vector
    camera.position.add(dispVector);
}

You can apply this same idea to the other keys: (-0.1, 0, 0) if you want to move left, or (0, 0.1, 0) if you want to move up, etc:

function onLeftKey() {
    dispVector.set(-0.1, 0, 0); // Left key moves -0.1 on x axis
    applyDisplacement();
}

function onUpKey() {
    dispVector.set(0, 0.1, 0); // Left key moves 0.1 on y axis
    applyDisplacement();
}