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javascript - 如何将纹理图像映射到着色器几何体上？

问题描述

我有 2 个场景，在其中一个场景中，我将纹理图像映射到平面几何图形，我只是简单地渲染了它，在另一个场景中，我有一个带有着色器材质的立方体，现在我想要在第一个场景中显示的图像纹理被映射到立方体表面，但我不知道该怎么做，有人可以帮忙吗？

实际上没有足够的文档说明我想要做什么，而且我对 three.js 还是陌生的，所以我不知道我应该在我的 HTML 文件的顶点和片段着色器中做什么，只做了我之前提到的。

这是我在第一个场景中的纹理图像和平面几何图形和另一个场景中的立方体，以及我的片段和顶点着色器：

this.vertShader = document.getElementById('vertexShader').innerHTML;
this.fragShader = document.getElementById('fragmentShader').innerHTML;
var geometry = new THREE.BoxGeometry( 0.5, 0.5 );

var material = new THREE.MeshLambertMaterial( { color: "blue", wireframe: 
true} );
this.mesh = new THREE.Mesh( geometry, material );
this.scene.add( this.mesh );

var texture = new THREE.TextureLoader().load ('js/textures/earth.jpg');
var texMaterial = new THREE.MeshBasicMaterial( { map: texture } );
var texGeometry = new THREE.PlaneGeometry(1, 1);
this.texmesh = new THREE.Mesh(texGeometry, texMaterial);
this.texmesh.position.set(0,0,0);
this.texScene.add(this.texmesh);

顶点着色器：不同的vec2 vUv；

void main() {
    vUv = uv;

    gl_Position =   projectionMatrix * modelViewMatrix * 
vec4(position,1.0);
 }

片段着色器：统一的 sampler2D 纹理；

varying vec2 vUv;

void main() {
    gl_FragColor = texture2D(texture, vUv);
}

我希望立方体被纹理图像覆盖。

标签： javascriptthree.jsglsl

解决方案

在片段着色器中必须声明一个统一类型的变量sampler2D：

顶点着色器：

varying vec2 vUv;

void main() {
    vUv = uv;
    gl_Position = projectionMatrix * modelViewMatrix * vec4(position, 1.0);
}

片段着色器：

precision highp float;

uniform sampler2D u_texture; // <---------------------------------- texture sampler uniform

varying vec2 vUv;

void main(){
    gl_FragColor = texture2D(u_texture, vUv);
}

使用着色器THREE.ShaderMaterial可以创建一个。

首先加载纹理：

var texture = new THREE.TextureLoader().load ('js/textures/earth.jpg');

然后指定Uniform的集合（在这种情况下，只有纹理统一）： 

var uniforms = {
    u_texture: {type: 't', value: texture}
};

最后创建材质：

var material = new THREE.ShaderMaterial({  
      uniforms: uniforms,
      vertexShader: document.getElementById('vertex-shader').textContent,
      fragmentShader: document.getElementById('fragment-shader').textContent
});

该材料可以以与任何其他材料相同的方式使用，请参见示例：

(function onLoad() {
  var loader, camera, scene, renderer, orbitControls;
  
  init();
  animate();

  function createModel() {

    var texture = new THREE.TextureLoader().load( 'https://raw.githubusercontent.com/Rabbid76/graphics-snippets/master/resource/texture/Gominolas.png' );

    var uniforms = {
        u_texture: {type: 't', value: texture}
    };
        
    var material = new THREE.ShaderMaterial({  
          uniforms: uniforms,
          vertexShader: document.getElementById('vertex-shader').textContent,
          fragmentShader: document.getElementById('fragment-shader').textContent
    });

    var geometry = new THREE.BoxGeometry( 1, 1, 1 );
    var mesh = new THREE.Mesh(geometry, material);

    scene.add(mesh);
  }

  function init() {
    renderer = new THREE.WebGLRenderer({
      antialias: true,
      alpha: true
    });
    renderer.setPixelRatio(window.devicePixelRatio);
    renderer.setSize(window.innerWidth, window.innerHeight);
    renderer.shadowMap.enabled = true;
    document.body.appendChild(renderer.domElement);

    camera = new THREE.PerspectiveCamera(70, window.innerWidth / window.innerHeight, 1, 100);
    camera.position.set(0, 1, -2);

    loader = new THREE.TextureLoader();
    loader.setCrossOrigin("");

    scene = new THREE.Scene();
    scene.background = new THREE.Color(0xffffff);
    scene.add(camera);
    window.onresize = resize;
    
    orbitControls = new THREE.OrbitControls(camera);
    
    addGridHelper();
    createModel();
  }

  function addGridHelper() {
    
    var helper = new THREE.GridHelper(100, 100);
    helper.material.opacity = 0.25;
    helper.material.transparent = true;
    scene.add(helper);

    var axis = new THREE.AxesHelper(1000);
    scene.add(axis);
  }

  function resize() {
    
    var aspect = window.innerWidth / window.innerHeight;
    renderer.setSize(window.innerWidth, window.innerHeight);
    camera.aspect = aspect;
    camera.updateProjectionMatrix();
  }

  function animate() {
    requestAnimationFrame(animate);
    orbitControls.update();
    render();
  }

  function render() {
    renderer.render(scene, camera);
  }
})();
<script type='x-shader/x-vertex' id='vertex-shader'>
varying vec2 vUv;
void main() {
    vUv = uv;
    gl_Position = projectionMatrix * modelViewMatrix * vec4(position, 1.0);
}
</script>

<script type='x-shader/x-fragment' id='fragment-shader'>
precision highp float;
uniform sampler2D u_texture;
varying vec2 vUv;
void main(){
    gl_FragColor = texture2D(u_texture, vUv);
}
</script>

<script src="https://threejs.org/build/three.min.js"></script>
<script src="https://threejs.org/examples/js/controls/OrbitControls.js"></script>

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