Texture bug on r137

[Karbust]

Describe the bug

DDS and PNG textures lose all color, I don't know how to really explain, I attached screenshots bellow. Since I only use these 2 types of textures, I can't test other types.

If the browser has DDS support, it will be used, otherwise fallback to PNG. This happens on all browsers and devices I tested.

To Reproduce

Steps to reproduce the behavior:
Go to either of the live examples below and press on a weapon or amor icon, the differences will be visible.

Code

A code snippet of how I'm using it.

		const manager = new THREE.LoadingManager(() => {
			const loadingScreen = document.getElementById('loading-screen')
			if (loadingScreen) {
				loadingScreen.classList.add('fade-out')

				loadingScreen!.addEventListener('transitionend', onTransitionEnd)
			}
		})
		manager.addHandler(/\.dds$/i, new DDSLoader())

		const mtlLoader = new MTLLoader(manager)
		mtlLoader.setPath(url!)
		mtlLoader.load(`${model}.mtl`, (materials) => {
			materials.preload()

			const objLoader = new OBJLoader(manager)
			objLoader.setMaterials(materials)
			objLoader.setPath(url!)
			objLoader.load(`${model}.obj`, (object) => {
				object.scale.setScalar(1 / 200)

				object.traverse((child) => {
					child.frustumCulled = false
					if ((child as any).material instanceof THREE.MeshPhongMaterial) {
						(child as any).material.side = THREE.DoubleSide
					}
				})
				scene.add(object)
			}, undefined, (error) => console.error(error))
		})

Live example

• Public version with r136
• Dev version with r137

Screenshots

Public version with r136:

Dev version with r137

Platform:

• Device: Desktop, Mobile
• OS: Windows, Android
• Browser: Tested on Vivaldi (both Desktop and Android), Chrome, Firefox and Edge
• Three.js version: r137

[Mugen87]

This issue is related to the latest alpha change, see #23230.

The problem is that your asset is blended with the HTML background since for some reasons the DDS texture holds alpha values < 1.

One workaround to solve the issue is to add this block to your onLoad() callback:

object.traverse( function ( child ) {

     if ( child.material ) child.material.alphaWrite = false;

} );

This will define the material as opaque by setting a 1 alpha value to all fragments.

[Mugen87]

Here is a complete code example that should load the sword as expected. Note that since r137 you have to use an sRGB workflow when loading assets with OBJ/MTL loader. That means you need renderer.outputEncoding = THREE.sRGBEncoding;.

import * as THREE from 'three';

import { MTLLoader } from './jsm/loaders/MTLLoader.js';
import { OBJLoader } from './jsm/loaders/OBJLoader.js';
import { DDSLoader } from './jsm/loaders/DDSLoader.js';
import { OrbitControls } from './jsm/controls/OrbitControls.js';

let camera, scene, renderer;

init();
animate();

function init() {

	const container = document.createElement( 'div' );
	document.body.appendChild( container );

	camera = new THREE.PerspectiveCamera( 45, window.innerWidth / window.innerHeight, 1, 2000 );
	camera.position.set( 250, 250, 0 );
	camera.lookAt( 0, 0, 0 );

	// scene

	scene = new THREE.Scene();
	scene.background = new THREE.Color( 0xcccccc );

	const ambientLight = new THREE.AmbientLight( 0xcccccc, 0.4 );
	scene.add( ambientLight );

	const pointLight = new THREE.PointLight( 0xffffff, 0.8 );
	camera.add( pointLight );
	scene.add( camera );

	// model

	const manager = new THREE.LoadingManager();
	manager.addHandler( /\.dds$/i, new DDSLoader() );

	new MTLLoader( manager )
		.setPath( 'models/obj/temp1/' )
		.load( '00270.mtl', function ( materials ) {

			materials.preload();

			new OBJLoader( manager )
				.setMaterials( materials )
				.setPath( 'models/obj/temp1/' )
				.load( '00270.obj', function ( object ) {

					object.traverse( function ( child ) {

						if ( child.material ) child.material.alphaWrite = false;

					} );

					scene.add( object );

				}  );

		} );

	//
	//

	renderer = new THREE.WebGLRenderer();
	renderer.outputEncoding = THREE.sRGBEncoding;
	renderer.setPixelRatio( window.devicePixelRatio );
	renderer.setSize( window.innerWidth, window.innerHeight );
	container.appendChild( renderer.domElement );

	//

	window.addEventListener( 'resize', onWindowResize );

	const controls = new OrbitControls( camera, renderer.domElement );

}

function onWindowResize() {

	camera.aspect = window.innerWidth / window.innerHeight;
	camera.updateProjectionMatrix();

	renderer.setSize( window.innerWidth, window.innerHeight );

}


//

function animate() {

	requestAnimationFrame( animate );
	render();

}

function render() {

	renderer.render( scene, camera );

}

[Karbust]

Perfect, it worked.

I was reading the migration guide but I wasn't able to pinpoint where the problem was coming from.

Thank you.

[mrdoob]

Makes me wonder if this line:

three.js/src/renderers/webgl/WebGLPrograms.js

Line 181 in 6365075

alphaWrite: material.alphaWrite || material.transparent,

Should be this instead:

alphaWrite: material.alphaWrite && material.transparent,

This stuff hurts my brain a bit.

/cc @donmccurdy

[Mugen87]

I was reading the migration guide but I wasn't able to pinpoint where the problem was coming from.

I've added a note that OBJ/MTLLoader now requires a sRGB workflow and also the alphaWrite solution.

But I fear many user will not understand that 3D objects are potentially blended with the HTML background and thus don't understand the note in the migration guide. It seems these cases will require some support.

[Karbust]

alphaWrite: material.alphaWrite || material.transparent,

Makes me wonder if this line:

three.js/src/renderers/webgl/WebGLPrograms.js

Line 181 in 6365075

alphaWrite: material.alphaWrite || material.transparent,

Should be this instead:

alphaWrite: material.alphaWrite && material.transparent,

This stuff hurts my brain a bit.

/cc @donmccurdy

It didn't work, I edited it on the node_modules folder, also tried setting it to false, it stayed the same... (I kept the sRGBEncoding, only removed the alphaWrite's on the my side).

[mrdoob]

Oh, hmm...

Then maybe the problem is that material.blending is set to NormalBlending by default.

Maybe if transparent === false it should use NoBlending internally?

[Mugen87]

Having a different value of material.blending will not solve this particular issue. If the shader writes fragments with alpha values < 1, they will be blended with the HTML background. The only way to prevent this is to write/have 1 alpha values in the default framebuffer.

[mrdoob]

You're right: https://jsfiddle.net/zfgebmux/

[mrdoob]

So if transparent === false we have to add gl_FragColor.a = 1.0 chunk at the end then.

[Mugen87]

Maybe we should reconsider #23166 (comment) for a long-term and glTF compliant solution.

[mrdoob]

So if transparent === false we have to add gl_FragColor.a = 1.0 chunk at the end then.

Hmm, I already tried that.

And now that we are setting alpha: true in the context I'm re-reading this conversation with new eyes...

[mrdoob]

As far as I can see the only issue of #18631 is that it broke this use case:

Confirmed. This breaks AdditiveBlending when texture.a < 1 and material.transparent is false.

In this new world of alpha: true, I think I'm totally okay with breaking that use case.

And then we'll be able to get rid of material.alphaWrite.