我已经使用了 ThreeJS 的本教程https://threejsfundamentals.org/threejs/lessons/threejs-post-processing-3dlut.html
我想在视频上应用 LUT，但作为实验，尝试使用图像。而且我遇到了一个问题，即在应用 LUT 后，我的结果与 Photoshop 的结果不符。
看看下面的图片：
- 原来的
- 由 ThreeJS 应用的 Lut
- Photoshop 应用的 Lut
可以在其中重现问题的 JS 小提琴（代码几乎与源代码相同） https://jsfiddle.net/Eugene_Ilyin/2e56mzaw/13/ 可以在代码中找到指向 PNG LUT 的链接或使用直接链接https://i.ibb .co/CJ27jKF/bthree-s8.png
html, body {
margin: 0;
height: 100%;
}
#c {
width: 100%;
height: 100%;
display: block;
}<canvas id="c"></canvas>
<script type="module">
// Three.js - postprocessing - 3DLUT w/loader
// from https://threejsfundamentals.org/threejs/threejs-postprocessing-3dlut-w-loader.html
import * as lutParser from 'https://threejsfundamentals.org/threejs/resources/lut-reader.js';
import * as dragAndDrop from 'https://threejsfundamentals.org/threejs/resources/drag-and-drop.js';
import * as THREE from 'https://threejsfundamentals.org/threejs/resources/threejs/r119/build/three.module.js';
import {OrbitControls} from 'https://threejsfundamentals.org/threejs/resources/threejs/r119/examples/jsm/controls/OrbitControls.js';
import {GLTFLoader} from 'https://threejsfundamentals.org/threejs/resources/threejs/r119/examples/jsm/loaders/GLTFLoader.js';
import {EffectComposer} from 'https://threejsfundamentals.org/threejs/resources/threejs/r119/examples/jsm/postprocessing/EffectComposer.js';
import {RenderPass} from 'https://threejsfundamentals.org/threejs/resources/threejs/r119/examples/jsm/postprocessing/RenderPass.js';
import {ShaderPass} from 'https://threejsfundamentals.org/threejs/resources/threejs/r119/examples/jsm/postprocessing/ShaderPass.js';
import {GUI} from 'https://threejsfundamentals.org/threejs/../3rdparty/dat.gui.module.js';
function main() {
const canvas = document.querySelector('#c');
const renderer = new THREE.WebGLRenderer({canvas});
const fov = 45;
const aspect = 2; // the canvas default
const near = 0.1;
const far = 100;
const camera = new THREE.PerspectiveCamera(fov, aspect, near, far);
camera.position.set(0, 10, 20);
const controls = new OrbitControls(camera, canvas);
controls.target.set(0, 5, 0);
controls.update();
const lutTextures = [
{ name: 'identity', size: 2, filter: true , },
{ name: 'identity no filter', size: 2, filter: false, },
{ name: 'MY LUT', size: 8, filter: true, url: 'https://i.ibb.co/CJ27jKF/bthree-s8.png' }
];
const makeIdentityLutTexture = function() {
const identityLUT = new Uint8Array([
0, 0, 0, 255, // black
255, 0, 0, 255, // red
0, 0, 255, 255, // blue
255, 0, 255, 255, // magenta
0, 255, 0, 255, // green
255, 255, 0, 255, // yellow
0, 255, 255, 255, // cyan
255, 255, 255, 255, // white
]);
return function(filter) {
const texture = new THREE.DataTexture(identityLUT, 4, 2, THREE.RGBAFormat);
texture.minFilter = filter;
texture.magFilter = filter;
texture.needsUpdate = true;
texture.flipY = false;
return texture;
};
}();
const makeLUTTexture = function() {
const imgLoader = new THREE.ImageLoader();
const ctx = document.createElement('canvas').getContext('2d');
return function(info) {
const texture = makeIdentityLutTexture(
info.filter ? THREE.LinearFilter : THREE.NearestFilter);
if (info.url) {
const lutSize = info.size;
// set the size to 2 (the identity size). We'll restore it when the
// image has loaded. This way the code using the lut doesn't have to
// care if the image has loaded or not
info.size = 2;
imgLoader.load(info.url, function(image) {
const width = lutSize * lutSize;
const height = lutSize;
info.size = lutSize;
ctx.canvas.width = width;
ctx.canvas.height = height;
ctx.drawImage(image, 0, 0);
const imageData = ctx.getImageData(0, 0, width, height);
texture.image.data = new Uint8Array(imageData.data.buffer);
texture.image.width = width;
texture.image.height = height;
texture.needsUpdate = true;
});
}
return texture;
};
}();
lutTextures.forEach((info) => {
// if not size set get it from the filename
if (!info.size) {
// assumes filename ends in '-s<num>[n]'
// where <num> is the size of the 3DLUT cube
// and [n] means 'no filtering' or 'nearest'
//
// examples:
// 'foo-s16.png' = size:16, filter: true
// 'bar-s8n.png' = size:8, filter: false
const m = /-s(\d+)(n*)\.[^.]+$/.exec(info.url);
if (m) {
info.size = parseInt(m[1]);
info.filter = info.filter === undefined ? m[2] !== 'n' : info.filter;
}
}
info.texture = makeLUTTexture(info);
});
let lutNameIndexMap = {};
function makeLutNameIndexMap() {
lutNameIndexMap = {};
lutTextures.forEach((info, ndx) => {
lutNameIndexMap[info.name] = ndx;
});
}
makeLutNameIndexMap(); // called so we can set lutSettings below
const lutSettings = {
dummy: () => {},
lut: lutNameIndexMap.identity,
};
const gui = new GUI({ width: 300 });
gui.addFolder('Choose LUT or Drag&Drop LUT File(s)');
let lutGUI;
function updateGUI() {
makeLutNameIndexMap();
if (lutGUI) {
gui.remove(lutGUI);
}
lutGUI = gui.add(lutSettings, 'lut', lutNameIndexMap);
}
updateGUI();
const scene = new THREE.Scene();
const sceneBG = new THREE.Scene();
const cameraBG = new THREE.OrthographicCamera(-1, 1, 1, -1, -1, 1);
let bgMesh;
let bgTexture;
{
const loader = new THREE.TextureLoader();
bgTexture = loader.load('https://i.ibb.co/XDTN30r/source.png');
const planeGeo = new THREE.PlaneBufferGeometry(2, 2);
const planeMat = new THREE.MeshBasicMaterial({
map: bgTexture,
depthTest: false,
});
bgMesh = new THREE.Mesh(planeGeo, planeMat);
sceneBG.add(bgMesh);
}
function frameArea(sizeToFitOnScreen, boxSize, boxCenter, camera) {
const halfSizeToFitOnScreen = sizeToFitOnScreen * 0.5;
const halfFovY = THREE.MathUtils.degToRad(camera.fov * .5);
const distance = halfSizeToFitOnScreen / Math.tan(halfFovY);
// compute a unit vector that points in the direction the camera is now
// in the xz plane from the center of the box
const direction = (new THREE.Vector3())
.subVectors(camera.position, boxCenter)
.multiply(new THREE.Vector3(1, 0, 1))
.normalize();
// move the camera to a position distance units way from the center
// in whatever direction the camera was from the center already
camera.position.copy(direction.multiplyScalar(distance).add(boxCenter));
// pick some near and far values for the frustum that
// will contain the box.
camera.near = boxSize / 100;
camera.far = boxSize * 100;
camera.updateProjectionMatrix();
// point the camera to look at the center of the box
camera.lookAt(boxCenter.x, boxCenter.y, boxCenter.z);
}
{
/* const gltfLoader = new GLTFLoader();
gltfLoader.load('https://threejsfundamentals.org/threejs/resources/models/3dbustchallange_submission/scene.gltf', (gltf) => {
const root = gltf.scene;
scene.add(root);
// fix materials from r114
root.traverse(({material}) => {
if (material) {
material.depthWrite = true;
}
});
root.updateMatrixWorld();
// compute the box that contains all the stuff
// from root and below
const box = new THREE.Box3().setFromObject(root);
const boxSize = box.getSize(new THREE.Vector3()).length();
const boxCenter = box.getCenter(new THREE.Vector3());
frameArea(boxSize * 0.4, boxSize, boxCenter, camera);
// update the Trackball controls to handle the new size
controls.maxDistance = boxSize * 10;
controls.target.copy(boxCenter);
controls.update();
}); */
}
const lutShader = {
uniforms: {
tDiffuse: { value: null },
lutMap: { value: null },
lutMapSize: { value: 1, },
},
vertexShader: `
varying vec2 vUv;
void main() {
vUv = uv;
gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );
}
`,
fragmentShader: `
#include <common>
#define FILTER_LUT true
uniform sampler2D tDiffuse;
uniform sampler2D lutMap;
uniform float lutMapSize;
varying vec2 vUv;
vec4 sampleAs3DTexture(sampler2D tex, vec3 texCoord, float size) {
float sliceSize = 1.0 / size; // space of 1 slice
float slicePixelSize = sliceSize / size; // space of 1 pixel
float width = size - 1.0;
float sliceInnerSize = slicePixelSize * width; // space of size pixels
float zSlice0 = floor( texCoord.z * width);
float zSlice1 = min( zSlice0 + 1.0, width);
float xOffset = slicePixelSize * 0.5 + texCoord.x * sliceInnerSize;
float yRange = (texCoord.y * width + 0.5) / size;
float s0 = xOffset + (zSlice0 * sliceSize);
#ifdef FILTER_LUT
float s1 = xOffset + (zSlice1 * sliceSize);
vec4 slice0Color = texture2D(tex, vec2(s0, yRange));
vec4 slice1Color = texture2D(tex, vec2(s1, yRange));
float zOffset = mod(texCoord.z * width, 1.0);
return mix(slice0Color, slice1Color, zOffset);
#else
return texture2D(tex, vec2( s0, yRange));
#endif
}
void main() {
vec4 originalColor = texture2D(tDiffuse, vUv);
gl_FragColor = sampleAs3DTexture(lutMap, originalColor.xyz, lutMapSize);
}
`,
};
const lutNearestShader = {
uniforms: {...lutShader.uniforms},
vertexShader: lutShader.vertexShader,
fragmentShader: lutShader.fragmentShader.replace('#define FILTER_LUT', '//'),
};
const effectLUT = new ShaderPass(lutShader);
effectLUT.renderToScreen = true;
const effectLUTNearest = new ShaderPass(lutNearestShader);
effectLUTNearest.renderToScreen = true;
const renderModel = new RenderPass(scene, camera);
renderModel.clear = false; // so we don't clear out the background
const renderBG = new RenderPass(sceneBG, cameraBG);
const rtParameters = {
minFilter: THREE.LinearFilter,
magFilter: THREE.LinearFilter,
format: THREE.RGBFormat,
};
const composer = new EffectComposer(renderer, new THREE.WebGLRenderTarget(1, 1, rtParameters));
composer.addPass(renderBG);
//composer.addPass(renderModel);
composer.addPass(effectLUT);
//composer.addPass(effectLUTNearest);
function resizeRendererToDisplaySize(renderer) {
const canvas = renderer.domElement;
const width = canvas.clientWidth * window.devicePixelRatio | 0;
const height = canvas.clientHeight * window.devicePixelRatio | 0;
const needResize = canvas.width !== width || canvas.height !== height;
if (needResize) {
renderer.setSize(width, height, false);
}
return needResize;
}
let then = 0;
function render(now) {
now *= 0.001; // convert to seconds
const delta = now - then;
then = now;
if (resizeRendererToDisplaySize(renderer)) {
const canvas = renderer.domElement;
const canvasAspect = canvas.clientWidth / canvas.clientHeight;
camera.aspect = canvasAspect;
camera.updateProjectionMatrix();
composer.setSize(canvas.width, canvas.height);
// scale the background plane to keep the image's
// aspect correct.
// Note the image may not have loaded yet.
const imageAspect = bgTexture.image ? bgTexture.image.width / bgTexture.image.height : 1;
const aspect = imageAspect / canvasAspect;
bgMesh.scale.x = aspect > 1 ? aspect : 1;
bgMesh.scale.y = aspect > 1 ? 1 : 1 / aspect;
}
const lutInfo = lutTextures[ lutSettings.lut ];
const effect = lutInfo.filter ? effectLUT : effectLUTNearest;
effectLUT.enabled = lutInfo.filter;
effectLUTNearest.enabled = !lutInfo.filter;
const lutTexture = lutInfo.texture;
effect.uniforms.lutMap.value = lutTexture;
effect.uniforms.lutMapSize.value = lutInfo.size;
composer.render(delta);
requestAnimationFrame(render);
}
requestAnimationFrame(render);
dragAndDrop.setup({msg: 'Drop LUT File here'});
dragAndDrop.onDropFile(readLUTFile);
function readLUTFile(file) {
const reader = new FileReader();
reader.onload = (e) => {
const lut = lutParser.lutTo2D3Drgb8(lutParser.parse(e.target.result));
const {size, data, name} = lut;
const texture = new THREE.DataTexture(data, size * size, size, THREE.RGBFormat);
texture.minFilter = THREE.LinearFilter;
texture.needsUpdate = true;
texture.flipY = false;
const lutTexture = {
name: (name && name.toLowerCase().trim() !== 'untitled')
? name
: file.name,
size: size,
filter: true,
texture,
};
lutTextures.push(lutTexture);
lutSettings.lut = lutTextures.length - 1;
updateGUI();
};
reader.readAsText(file);
}
}
main();
</script>我的问题是如何使用 ThreeJS 获得有效结果？欢迎任何其他选项如何解决我的问题（请记住我想在视频上应用 LUT）。