我正在制作一张Three.js图表，它基本上代表了2D平面中的一堆图像。
现在，各个图像分别是32px×32px的较大2048px到2048px图像图集文件。当用户放大到场景的特定区域时，我想增加这些单个图像的大小。例如，如果用户开始放大空间最右侧区域的图像，我计划使用相同内容的64px x 64px图像更新该区域中的32px x 32px单个图像（以显示更多细节）。
我的问题是：实现这一目标的Three.js方法是什么？
我的平脚计划是加载更高分辨率的资源，将它们映射到正确的几何坐标，然后简单地删除具有32px子图像的旧网格，并添加具有64px子图像的新网格。我原本以为我可以更新现有几何体的纹理/材质，但我读过不应该使用大于2048px到2048px的纹理，而具有n个点的几何体将不允许我不断提高保真度该几何图像中的图像没有超过最大纹理尺寸。
我非常感谢Three.js的老手可以提供他们如何处理这项任务的任何见解！
完整代码：
/**
* Globals
**/
// Identify data endpoint
var dataUrl = 'https://s3.amazonaws.com/duhaime/blog/tsne-webgl/data/';
// Create global stores for image and atlas sizes
var image, atlas;
// Create a store for image position information
var imagePositions = null;
// Create a store for the load progress. Data structure:
// {atlas0: percentLoaded, atlas1: percentLoaded}
var loadProgress = {};
// Create a store for the image atlas materials. Data structure:
// {subImageSize: {atlas0: material, atlas1: material}}
var materials = {32: {}, 64: {}};
// Create a store for meshes
var meshes = [];
/**
* Create Scene
**/
// Create the scene and a camera to view it
var scene = new THREE.Scene();
/**
* Camera
**/
// Specify the portion of the scene visiable at any time (in degrees)
var fieldOfView = 75;
// Specify the camera's aspect ratio
var aspectRatio = window.innerWidth / window.innerHeight;
/*
Specify the near and far clipping planes. Only objects
between those planes will be rendered in the scene
(these values help control the number of items rendered
at any given time)
*/
var nearPlane = 100;
var farPlane = 50000;
// Use the values specified above to create a camera
var camera = new THREE.PerspectiveCamera(
fieldOfView, aspectRatio, nearPlane, farPlane
);
// Finally, set the camera's position
camera.position.z = 12000;
camera.position.y = -2000;
/**
* Lights
**/
// Add a point light with #fff color, .7 intensity, and 0 distance
var light = new THREE.PointLight( 0xffffff, 1, 0 );
// Specify the light's position
light.position.set( 1, 1, 100 );
// Add the light to the scene
scene.add(light)
/**
* Renderer
**/
// Create the canvas with a renderer
var renderer = new THREE.WebGLRenderer({ antialias: true });
// Add support for retina displays
renderer.setPixelRatio( window.devicePixelRatio );
// Specify the size of the canvas
renderer.setSize( window.innerWidth, window.innerHeight );
// Add the canvas to the DOM
document.body.appendChild( renderer.domElement );
/**
* Load External Data
**/
// Load the image position JSON file
var fileLoader = new THREE.FileLoader();
var url = dataUrl + 'image_tsne_projections.json';
fileLoader.load(url, function(data) {
imagePositions = JSON.parse(data);
conditionallyBuildGeometries(32)
})
/**
* Load Atlas Textures
**/
// List of all textures to be loaded, the size of subimages
// in each, and the total count of atlas files for each size
var textureSets = {
32: { size: 32, count: 5 },
64: { size: 64, count: 20 }
}
// Create a texture loader so we can load our image files
var textureLoader = new AjaxTextureLoader();
function loadTextures(size, onProgress) {
setImageAndAtlasSize(size)
for (var i=0; i<textureSets[size].count; i++) {
var url = dataUrl + 'atlas_files/' + size + 'px/atlas-' + i + '.jpg';
if (onProgress) {
textureLoader.load(url,
handleTexture.bind(null, size, i),
onProgress.bind(null, size, i));
} else {
textureLoader.load(url, handleTexture.bind(null, size, i));
}
}
}
function handleProgress(size, idx, xhr) {
loadProgress[idx] = xhr.loaded / xhr.total;
var sum = 0;
Object.keys(loadProgress).forEach(function(k) { sum += loadProgress[k]; })
var progress = sum/textureSets[size].count;
var loader = document.querySelector('#loader');
progress < 1
? loader.innerHTML = parseInt(progress * 100) + '%'
: loader.style.display = 'none';
}
// Create a material from the new texture and call
// the geometry builder if all textures have loaded
function handleTexture(size, idx, texture) {
var material = new THREE.MeshBasicMaterial({ map: texture });
materials[size][idx] = material;
conditionallyBuildGeometries(size, idx)
}
// If the textures and the mapping from image idx to positional information
// are all loaded, create the geometries
function conditionallyBuildGeometries(size, idx) {
if (size === 32) {
var nLoaded = Object.keys(materials[size]).length;
var nRequired = textureSets[size].count;
if (nLoaded === nRequired && imagePositions) {
// Add the low-res textures and load the high-res textures
buildGeometry(size);
loadTextures(64)
}
} else {
// Add the new high-res texture to the scene
updateMesh(size, idx)
}
}
loadTextures(32, handleProgress)
/**
* Build Image Geometry
**/
// Iterate over the textures in the current texture set
// and for each, add a new mesh to the scene
function buildGeometry(size) {
for (var i=0; i<textureSets[size].count; i++) {
// Create one new geometry per set of 1024 images
var geometry = new THREE.Geometry();
geometry.faceVertexUvs[0] = [];
for (var j=0; j<atlas.cols*atlas.rows; j++) {
var coords = getCoords(i, j);
geometry = updateVertices(geometry, coords);
geometry = updateFaces(geometry);
geometry = updateFaceVertexUvs(geometry, j);
if ((j+1)%1024 === 0) {
var idx = (i*textureSets[size].count) + j;
buildMesh(geometry, materials[size][i], idx);
var geometry = new THREE.Geometry();
}
}
}
}
// Get the x, y, z coords for the subimage at index position j
// of atlas in index position i
function getCoords(i, j) {
var idx = (i * atlas.rows * atlas.cols) + j;
var coords = imagePositions[idx];
coords.x *= 2200;
coords.y *= 1200;
coords.z = (-200 + j/10);
return coords;
}
// Add one vertex for each corner of the image, using the
// following order: lower left, lower right, upper right, upper left
function updateVertices(geometry, coords) {
// Retrieve the x, y, z coords for this subimage
geometry.vertices.push(
new THREE.Vector3(
coords.x,
coords.y,
coords.z
),
new THREE.Vector3(
coords.x + image.shownWidth,
coords.y,
coords.z
),
new THREE.Vector3(
coords.x + image.shownWidth,
coords.y + image.shownHeight,
coords.z
),
new THREE.Vector3(
coords.x,
coords.y + image.shownHeight,
coords.z
)
);
return geometry;
}
// Create two new faces for a given subimage, then add those
// faces to the geometry
function updateFaces(geometry) {
// Add the first face (the lower-right triangle)
var faceOne = new THREE.Face3(
geometry.vertices.length-4,
geometry.vertices.length-3,
geometry.vertices.length-2
)
// Add the second face (the upper-left triangle)
var faceTwo = new THREE.Face3(
geometry.vertices.length-4,
geometry.vertices.length-2,
geometry.vertices.length-1
)
// Add those faces to the geometry
geometry.faces.push(faceOne, faceTwo);
return geometry;
}
function updateFaceVertexUvs(geometry, j) {
// Identify the relative width and height of the subimages
// within the image atlas
var relativeW = image.width / atlas.width;
var relativeH = image.height / atlas.height;
// Identify this subimage's offset in the x dimension
// An xOffset of 0 means the subimage starts flush with
// the left-hand edge of the atlas
var xOffset = (j % atlas.cols) * relativeW;
// Identify this subimage's offset in the y dimension
// A yOffset of 0 means the subimage starts flush with
// the bottom edge of the atlas
var yOffset = 1 - (Math.floor(j/atlas.cols) * relativeH) - relativeH;
// Determine the faceVertexUvs index position
var faceIdx = 2 * (j%1024);
// Use the xOffset and yOffset (and the knowledge that
// each row and column contains only 32 images) to specify
// the regions of the current image. Use .set() if the given
// faceVertex is already defined, due to a bug in updateVertexUvs:
// https://github.com/mrdoob/three.js/issues/7179
if (geometry.faceVertexUvs[0][faceIdx]) {
geometry.faceVertexUvs[0][faceIdx][0].set(xOffset, yOffset)
geometry.faceVertexUvs[0][faceIdx][1].set(xOffset + relativeW, yOffset)
geometry.faceVertexUvs[0][faceIdx][2].set(xOffset + relativeW, yOffset + relativeH)
} else {
geometry.faceVertexUvs[0][faceIdx] = [
new THREE.Vector2(xOffset, yOffset),
new THREE.Vector2(xOffset + relativeW, yOffset),
new THREE.Vector2(xOffset + relativeW, yOffset + relativeH)
]
}
// Map the region of the image described by the lower-left,
// upper-right, and upper-left vertices to `faceTwo`
if (geometry.faceVertexUvs[0][faceIdx+1]) {
geometry.faceVertexUvs[0][faceIdx+1][0].set(xOffset, yOffset)
geometry.faceVertexUvs[0][faceIdx+1][1].set(xOffset + relativeW, yOffset + relativeH)
geometry.faceVertexUvs[0][faceIdx+1][2].set(xOffset, yOffset + relativeH)
} else {
geometry.faceVertexUvs[0][faceIdx+1] = [
new THREE.Vector2(xOffset, yOffset),
new THREE.Vector2(xOffset + relativeW, yOffset + relativeH),
new THREE.Vector2(xOffset, yOffset + relativeH)
]
}
return geometry;
}
function buildMesh(geometry, material, idx) {
// Convert the geometry to a BuferGeometry for additional performance
//var geometry = new THREE.BufferGeometry().fromGeometry(geometry);
// Combine the image geometry and material into a mesh
var mesh = new THREE.Mesh(geometry, material);
// Store this image's index position in the mesh
mesh.userData.idx = idx;
// Set the position of the image mesh in the x,y,z dimensions
mesh.position.set(0,0,0)
// Add the image to the scene
scene.add(mesh);
// Save this mesh
meshes.push(mesh);
return mesh;
}
/**
* Update Geometries with new VertexUvs and materials
**/
function updateMesh(size, idx) {
// Update the appropriate material
meshes[idx].material = materials[size][idx];
meshes[idx].material.needsUpdate = true;
// Update the facevertexuvs
for (var j=0; j<atlas.cols*atlas.rows; j++) {
meshes[idx].geometry = updateFaceVertexUvs(meshes[idx].geometry, j);
}
meshes[idx].geometry.uvsNeedUpdate = true;
meshes[idx].geometry.verticesNeedUpdate = true;
}
/**
* Helpers
**/
function setImageAndAtlasSize(size) {
// Identify the subimage size in px (width/height) and the
// size of the image as it will be displayed in the map
image = { width: size, height: size, shownWidth: 64, shownHeight: 64 };
// Identify the total number of cols & rows in the image atlas
atlas = { width: 2048, height: 2048, cols: 2048/size, rows: 2048/size };
}
/**
* Add Controls
**/
var controls = new THREE.TrackballControls(camera, renderer.domElement);
/**
* Add Raycaster
**/
var raycaster = new THREE.Raycaster();
var mouse = new THREE.Vector2();
function onMouseMove( event ) {
// Calculate mouse position in normalized device coordinates
// (-1 to +1) for both components
mouse.x = ( event.clientX / window.innerWidth ) * 2 - 1;
mouse.y = - ( event.clientY / window.innerHeight ) * 2 + 1;
}
function onClick( event ) {
// Determine which image is selected (if any)
var selected = raycaster.intersectObjects( scene.children );
// Intersecting elements are ordered by their distance (increasing)
if (!selected) return;
if (selected.length) {
selected = selected[0];
console.log('clicked', selected.object.userData.idx)
}
}
window.addEventListener('mousemove', onMouseMove)
window.addEventListener('click', onClick)
/**
* Handle window resizes
**/
window.addEventListener('resize', function() {
camera.aspect = window.innerWidth / window.innerHeight;
camera.updateProjectionMatrix();
renderer.setSize( window.innerWidth, window.innerHeight );
controls.handleResize();
});
/**
* Render!
**/
// The main animation function that re-renders the scene each animation frame
function animate() {
requestAnimationFrame( animate );
raycaster.setFromCamera( mouse, camera );
renderer.render( scene, camera );
controls.update();
}
animate();* {
margin: 0;
padding: 0;
background: #000;
color: #fff;
}<script src="https://cdnjs.cloudflare.com/ajax/libs/three.js/88/three.min.js"></script>
<script src="https://s3.amazonaws.com/duhaime/blog/tsne-webgl/assets/js/texture-loader.js"></script>
<script src="https://s3.amazonaws.com/duhaime/blog/tsne-webgl/assets/js/trackball-controls.js"></script>
<div id='loader'>0%</div>
答案 0 :(得分：2)
您可以使用多种材质和几何图形组（或者在您的情况下，使用材质索引）。
这取决于缩放1 :: 1的纹理尺寸。换句话说，如果您的第一个分辨率为尺寸32x64，则该分辨率的两倍应具有64x128的尺寸。 UV是基于百分比的，因此从一个分辨率的图像移动到另一个分辨率的同一图像＃34;只是工作＆＃34;。
此时，您真的只需要更改纹理图像源。但听起来你并不想这样做。因此，我们需要一次将所有纹理分配给同一个Mesh。 Three.js让这很容易......
var myMesh = new THREE.Mesh(myGeometry, [ material1, material2, material3 ]);
请注意，材质参数定义为数组。每种材质都有不同的纹理，在您的情况下是不同的分辨率图像。
现在，调试到Mesh。在goemetry属性下，您将看到一个名为faces的属性，该属性是Face3个对象的数组。每张脸都有一个名为materialIndex的属性。这是面对材料阵列的参考。
当您到达想要触发更改的点（例如您的相机距离网格一定距离）时，您可以更改材质索引，然后触发网格以更改其材质：
var distance = camera.position.distanceTo(myMesh.position);
if(distance < 50){
myMesh.faces.forEach(function(face){
face.materialIndex = 2;
});
}
else if(distance => 50 && distance < 100){
myMesh.faces.forEach(function(face){
face.materialIndex = 1;
});
}
else{
myMesh.faces.forEach(function(face){
face.materialIndex = 0;
});
}
myMesh.groupsNeedUpdate = true;
最后一行（myMesh.groupsNeedUpdate = true;）告诉渲染器材质索引已更改，因此需要更新渲染的材质。
答案 1 :(得分：1)