THREE.js - 旋转移动3D球

Question

我是THREE.js的新手，对物理知识知之甚少 - 但我正在尝试建立一个足球游戏引擎（从顶部看），现在我正在努力控制球的运动。

当试图将球从一侧移动到另一侧时，旋转始终面向一个方向，我不明白如何使其沿着其移动的方向旋转。

我添加了一个显示此问题的简单代码。非常感谢您的帮助。

     /*
            *
            * SET UP MOTION PARAMS
            * 
            */

            var degrees = 10;
            var power = 1;
            var angleRad = degrees * Math.PI / 120;

            var velocityX = Math.cos(angleRad) * power;
            var velocityY = Math.sin(angleRad) * power;
            var velocityZ = 1;

            var friction = 1;
            var gravity = 0.2;
            var bounciness = 0.9;



            window.onload = function (params) {

                /*
                *
                * SET UP THE WORLD
                * 
                */
                
                
                
                //set up the ratio
                var gWidth = window.innerWidth;
                var gHeight = window.innerHeight;
                var ratio = gWidth / gHeight;
                var borders = [40, 24] //indicate where the ball needs to move in mirror position


                //set the scene
                scene = new THREE.Scene();
                scene.background = new THREE.Color(0xeaeaea);

                //set the camera
                var camera = new THREE.PerspectiveCamera(35, ratio, 0.1, 1000);
                camera.position.z = 120;   

                //set the light
                var light = new THREE.SpotLight(0xffffff, 1);
                light.position.set(100, 1, 0); 		
                light.castShadow = true;         
                light.position.set(0, 0, 100);
                scene.add(light);

                //  set the renderer 
                var renderer = new THREE.WebGLRenderer();

                //properties for casting shadow
                renderer.shadowMap.enabled = true;
                renderer.shadowMap.type = THREE.PCFSoftShadowMap; 

                renderer.setSize(gWidth, gHeight);
                document.body.appendChild(renderer.domElement);



                
                /*
                *
                * ADD MESH TO SCENE
                * 
                */


                // create and add the ball
                var geometry = new THREE.SphereGeometry(5, 5, 5);
                var material = new THREE.MeshLambertMaterial({ color: 'gray' });
                var ball = new THREE.Mesh(geometry, material);

                ball.castShadow = true;
                ball.receiveShadow = false;
                scene.add(ball);


                
                // create and add the field
                var margin = 20;
                var fieldRatio = 105 / 68;

                var width = 90;
                var height = width / fieldRatio;

                var material = new THREE.MeshLambertMaterial({ color: 'green' });
                var geometry = new THREE.BoxGeometry(width, height, 1);
                var field = new THREE.Mesh(geometry, material);

                field.receiveShadow = true;
                field.position.z = -1;
                scene.add(field);




                /*
                * setting up rotation axis 
                */


                var rotation_matrix = null;

                var setQuaternions = function () {
                    setMatrix();
                    ball.rotation.set(Math.PI / 2, Math.PI / 4, Math.PI / 4); // Set initial rotation
                    ball.matrix.makeRotationFromEuler(ball.rotation); // Apply rotation to the object's matrix
                }

                var setMatrix = function () {
                    rotation_matrix = new THREE.Matrix4().makeRotationZ(angleRad); // Animated rotation will be in .01 radians along object's X axis
                }

                setQuaternions();


                /*
                *
                * ANIMATION STEP
                * 
                */

                var render = function (params) {

                    // add velocity to ball
                    ball.position.x += velocityX;
                    ball.position.z += velocityZ;
                    ball.position.y += velocityY;


                    //validate if ball is stop moving
                    if (Math.abs(velocityX) < 0.02 && Math.abs(velocityY) < 0.02) {
                        console.log("DONE!");
                        return;
                    }



                    // handle boucing effect
                    if (ball.position.z < 1) {
                        velocityZ *= -bounciness;
                        ball.position.z = 1
                    }


                    // Update the object's rotation & apply it
                    ball.matrix.multiply(rotation_matrix);
                    ball.rotation.setFromRotationMatrix(ball.matrix);


                    //reducing speed by friction
                    angleRad *= friction;
                    velocityX *= friction;
                    velocityY *= friction;
                    velocityZ *= friction;


                    //set up the matrix 
                    setMatrix();
                    


                    //validate ball is withing its borders otherwise go in the mirror direction
                    if (Math.abs(ball.position.x) > borders[0]) {
                        velocityX *= -1;
                        ball.position.x = (ball.position.x < 0) ? borders[0] * -1 : borders[0];
                    }

                    if (Math.abs(ball.position.y) > borders[1]) {
                        velocityY *= -1;
                        ball.position.y = (ball.position.y < 0) ? borders[1] * -1 : borders[1];
                    }


                    // reduce ball height with gravity
                    velocityZ -= gravity;

                    

                    //render the page
                    renderer.render(scene, camera);

                    requestAnimationFrame(render);
                }

                render();

            }

body {
    padding: 0;
    margin: 0;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/three.js/96/three.min.js"></script>
<html>

<head>

</head>

<body>
</body>

</html>

Answer 1

另一答案