我正在尝试学习和理解 Three.js 的工作原理。我从创建布料模拟开始，但遇到了一个小故障。似乎将布料设置为 25 以上的宽度，使片段开始聚集。
我在 Cloth.js 文件中设置宽度var ySegs = 60;，在控制台中我收到警告“THREE.WebGLRenderer：图像不是二的幂 (1800x2819)。调整为 2048x2048”，这些问题是否相关？如果有人可以帮助我了解导致此问题的原因，将不胜感激。
// Cloth.js
var DAMPING = 0.03;
var DRAG = 1 - DAMPING;
var MASS = 0.1;
var restDistance = 25;
var xSegs = 12;
var ySegs = 25;
var clothFunction = plane( restDistance * xSegs, restDistance * ySegs );
var cloth = new Cloth( xSegs, ySegs );
var GRAVITY = 981 * 1.4;
var gravity = new THREE.Vector3( 0, - GRAVITY, 0 ).multiplyScalar( MASS );
var TIMESTEP = 18 / 1000;
var TIMESTEP_SQ = TIMESTEP * TIMESTEP;
var pins = [];
var wind = true;
var windStrength = 2;
var windForce = new THREE.Vector3( 0, 0, 0 );
var ballPosition = new THREE.Vector3( 0, - 45, 0 );
var ballSize = 60; //40
var tmpForce = new THREE.Vector3();
var lastTime;
function plane( width, height ) {
return function( u, v ) {
var x = ( u - 0.5 ) * width;
var y = ( v + 0.5 ) * height;
var z = 0;
return new THREE.Vector3( x, y, z );
};
}
function Particle( x, y, z, mass ) {
this.position = clothFunction( x, y ); // position
this.previous = clothFunction( x, y ); // previous
this.original = clothFunction( x, y );
this.a = new THREE.Vector3( 0, 0, 0 ); // acceleration
this.mass = mass;
this.invMass = 1 / mass;
this.tmp = new THREE.Vector3();
this.tmp2 = new THREE.Vector3();
}
// Force -> Acceleration
Particle.prototype.addForce = function( force ) {
this.a.add(
this.tmp2.copy( force ).multiplyScalar( this.invMass )
);
};
// Performs Verlet integration
Particle.prototype.integrate = function( timesq ) {
var newPos = this.tmp.subVectors( this.position, this.previous );
newPos.multiplyScalar( DRAG ).add( this.position );
newPos.add( this.a.multiplyScalar( timesq ) );
this.tmp = this.previous;
this.previous = this.position;
this.position = newPos;
this.a.set( 0, 0, 0 );
};
var diff = new THREE.Vector3();
function satisfyConstraints( p1, p2, distance ) {
diff.subVectors( p2.position, p1.position );
var currentDist = diff.length();
if ( currentDist === 0 ) return; // prevents division by 0
var correction = diff.multiplyScalar( 1 - distance / currentDist );
var correctionHalf = correction.multiplyScalar( 0.5 );
p1.position.add( correctionHalf );
p2.position.sub( correctionHalf );
}
function Cloth( w, h ) {
w = w || 10;
h = h || 10;
this.w = w;
this.h = h;
var particles = [];
var constraints = [];
var u, v;
// Create particles
for ( v = 0; v <= h; v ++ ) {
for ( u = 0; u <= w; u ++ ) {
particles.push(
new Particle( u / w, v / h, 0, MASS )
);
}
}
// Structural
for ( v = 0; v < h; v ++ ) {
for ( u = 0; u < w; u ++ ) {
constraints.push( [
particles[ index( u, v ) ],
particles[ index( u, v + 1 ) ],
restDistance
] );
constraints.push( [
particles[ index( u, v ) ],
particles[ index( u + 1, v ) ],
restDistance
] );
}
}
for ( u = w, v = 0; v < h; v ++ ) {
constraints.push( [
particles[ index( u, v ) ],
particles[ index( u, v + 1 ) ],
restDistance
] );
}
for ( v = h, u = 0; u < w; u ++ ) {
constraints.push( [
particles[ index( u, v ) ],
particles[ index( u + 1, v ) ],
restDistance
] );
}
this.particles = particles;
this.constraints = constraints;
function index( u, v ) {
return u + v * ( w + 1 );
}
this.index = index;
}
function simulate( time ) {
if ( ! lastTime ) {
lastTime = time;
return;
}
var i, il, particles, particle, pt, constraints, constraint;
// Aerodynamics forces
if ( wind ) {
var face, faces = clothGeometry.faces, normal;
particles = cloth.particles;
for ( i = 0, il = faces.length; i < il; i ++ ) {
face = faces[ i ];
normal = face.normal;
tmpForce.copy( normal ).normalize().multiplyScalar( normal.dot( windForce ) );
particles[ face.a ].addForce( tmpForce );
particles[ face.b ].addForce( tmpForce );
particles[ face.c ].addForce( tmpForce );
}
}
for ( particles = cloth.particles, i = 0, il = particles.length; i < il; i ++ ) {
particle = particles[ i ];
particle.addForce( gravity );
particle.integrate( TIMESTEP_SQ );
}
// Start Constraints
constraints = cloth.constraints;
il = constraints.length;
for ( i = 0; i < il; i ++ ) {
constraint = constraints[ i ];
satisfyConstraints( constraint[ 0 ], constraint[ 1 ], constraint[ 2 ] );
}
// Ball Constraints
ballPosition.z = - Math.sin( Date.now() / 600 ) * 90 ; //+ 40;
ballPosition.x = Math.cos( Date.now() / 400 ) * 70;
if ( sphere.visible ) {
for ( particles = cloth.particles, i = 0, il = particles.length; i < il; i ++ ) {
particle = particles[ i ];
var pos = particle.position;
diff.subVectors( pos, ballPosition );
if ( diff.length() < ballSize ) {
// collided
diff.normalize().multiplyScalar( ballSize );
pos.copy( ballPosition ).add( diff );
}
}
}
// Floor Constraints
for ( particles = cloth.particles, i = 0, il = particles.length; i < il; i ++ ) {
particle = particles[ i ];
pos = particle.position;
if ( pos.y < - 250 ) {
pos.y = - 250;
}
}
// Pin Constraints
for ( i = 0, il = pins.length; i < il; i ++ ) {
var xy = pins[ i ];
var p = particles[ xy ];
p.position.copy( p.original );
p.previous.copy( p.original );
}
}
/* Testing */
var pinsFormation = [];
var pins = [ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12];
pinsFormation.push( pins );
pins = pinsFormation[ 0 ];
function togglePins() {
pins = pinsFormation[ ~~ ( Math.random() * pinsFormation.length ) ];
}
var colours = [
{bg: 'rgb(56, 255, 211)', flag:'assets/images/rectangle_3.png'},
{bg: 'rgb(255, 190, 73)', flag:'assets/images/rectangle_1.png'},
{bg: 'rgb(227, 195, 255)', flag:'assets/images/rectangle_2.png'}
];
var colourChoice = colours[ ~~ ( Math.random() * colours.length ) ];
if ( ! Detector.webgl ) Detector.addGetWebGLMessage();
var container, stats;
var camera, scene, renderer;
var clothGeometry;
var sphere;
var object;
init();
animate();
function init() {
container = document.createElement('div');
container.setAttribute("id", "canvas-cnt");
document.body.appendChild( container );
// scene
scene = new THREE.Scene();
scene.background = new THREE.Color(colourChoice.bg);
// camera
camera = new THREE.PerspectiveCamera( 45, window.innerWidth / window.innerHeight, 1, 10000 );
camera.position.x = 0;
camera.position.y = -300;
camera.position.z = 1800;
scene.add(camera);
// lights
var light, materials;
scene.add( new THREE.AmbientLight( 0x666666 ) );
light = new THREE.DirectionalLight( 0xdfebff, 1.75 );
light.position.set( 50, 200, 100 );
light.position.multiplyScalar( 1.3 );
light.castShadow = true;
light.shadow.mapSize.width = 1024;
light.shadow.mapSize.height = 1024;
var d = 300;
light.shadow.camera.left = - d;
light.shadow.camera.right = d;
light.shadow.camera.top = d;
light.shadow.camera.bottom = - d;
light.shadow.camera.far = 1000;
scene.add( light );
// cloth material
var loader = new THREE.TextureLoader();
var clothTexture = loader.load(colourChoice.flag);
clothTexture.wrapS = clothTexture.wrapT = THREE.RepeatWrapping;
clothTexture.anisotropy = 16;
var clothMaterial = new THREE.MeshPhongMaterial( {
specular: 0x030303,
map: clothTexture,
side: THREE.DoubleSide,
alphaTest: 0.5
} );
// cloth geometry
clothGeometry = new THREE.ParametricGeometry( clothFunction, cloth.w, cloth.h );
clothGeometry.dynamic = true;
console.log(cloth.w, cloth.h);
var uniforms = { texture: { value: clothTexture } };
var vertexShader = document.getElementById( 'vertexShaderDepth' ).textContent;
var fragmentShader = document.getElementById( 'fragmentShaderDepth' ).textContent;
// cloth mesh
object = new THREE.Mesh( clothGeometry, clothMaterial );
object.position.set( 0, 130, 0 );
object.rotateZ( Math.PI / 2 );
object.castShadow = true;
scene.add( object );
object.customDepthMaterial = new THREE.ShaderMaterial( {
uniforms: uniforms,
vertexShader: vertexShader,
fragmentShader: fragmentShader,
side: THREE.DoubleSide
} );
// sphere
var ballGeo = new THREE.SphereGeometry( ballSize, 20, 20 );
var ballMaterial = new THREE.MeshPhongMaterial( { color: 0xaaaaaa } );
sphere = new THREE.Mesh( ballGeo, ballMaterial );
sphere.castShadow = true;
sphere.receiveShadow = true;
scene.add( sphere );
// renderer
renderer = new THREE.WebGLRenderer( { antialias: true } );
renderer.setPixelRatio( window.devicePixelRatio );
renderer.setSize( window.innerWidth, window.innerHeight );
renderer.shadowMap.renderSingleSided = false;
container.appendChild( renderer.domElement );
renderer.gammaInput = true;
renderer.gammaOutput = true;
renderer.shadowMap.enabled = true;
// controls
var controls = new THREE.OrbitControls( camera, renderer.domElement );
controls.maxPolarAngle = Math.PI * 0.5;
controls.minDistance = 1000;
controls.maxDistance = 7500;
// performance monitor
stats = new Stats();
container.appendChild( stats.dom );
//
window.addEventListener( 'resize', onWindowResize, false );
sphere.visible = ! true;
}
//
function onWindowResize() {
camera.aspect = window.innerWidth / window.innerHeight;
camera.updateProjectionMatrix();
renderer.setSize( window.innerWidth, window.innerHeight );
}
//
function animate() {
requestAnimationFrame( animate );
var time = Date.now();
var windStrength = 40;
windForce.set( 1000, 1000, 4200 )
windForce.normalize()
windForce.multiplyScalar( windStrength );
simulate( time );
render();
stats.update();
}
function render() {
var p = cloth.particles;
for ( var i = 0, il = p.length; i < il; i ++ ) {
clothGeometry.vertices[ i ].copy( p[ i ].position );
}
clothGeometry.computeFaceNormals();
clothGeometry.computeVertexNormals();
clothGeometry.normalsNeedUpdate = true;
clothGeometry.verticesNeedUpdate = true;
camera.lookAt( scene.position );
renderer.render( scene, camera );
}<script type="x-shader/x-fragment" id="fragmentShaderDepth">
#include <packing>
uniform sampler2D texture;
varying vec2 vUV;
void main() {
vec4 pixel = texture2D( texture, vUV );
if ( pixel.a < 0.5 ) discard;
gl_FragData[ 0 ] = packDepthToRGBA( gl_FragCoord.z );
}
</script>
<script type="x-shader/x-vertex" id="vertexShaderDepth">
varying vec2 vUV;
void main() {
vUV = 0.75 * uv;
vec4 mvPosition = modelViewMatrix * vec4( position, 1.0 );
gl_Position = projectionMatrix * mvPosition;
}
</script>