Three.js Tri-panner (三面贴图) 材质两种实现方式

本文主要是介绍Three.js Tri-panner (三面贴图) 材质两种实现方式，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

文章目录

- - - 介绍
    - - 自定义shader
      - NodeMaterial
      - 骨骼材质特殊处理

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介绍

Tri-panner 在babylonjs中有支持但是three.js目前的基础材质并不支持
需要自己定义shader 或者使用目前还没有什么完善的文档的 NodeMaterial

下面展示两种实现方式

自定义shader

/*** @description: 替换三角面贴图  https://doc.babylonjs.com/toolsAndResources/assetLibraries/materialsLibrary/triPlanarMat* @param {SingleMaterialMesh} mesh* @return {*}*/
export const useTriplanarMapping = (mesh: SingleMaterialMesh) => {const material = mesh.material.clone();mesh.material = material;material.map!.wrapS = THREE.RepeatWrapping;material.map!.wrapT = THREE.RepeatWrapping;material.onBeforeCompile = (shader) => {shader.vertexShader = shader.vertexShader.replace("#include <common>",`#include <common>varying vec3 tripPosition;varying vec3 tripNormal;`);shader.vertexShader = shader.vertexShader.replace("#include <fog_vertex>",`#include <fog_vertex>vec4 tripPosition4 = modelMatrix * vec4(position,1.) ;tripPosition = tripPosition4.xyz;tripNormal = normal * normalMatrix;vec3 world_space_normal = vec3(modelMatrix * vec4(normal, 0.0));tripNormal = normal;`);shader.fragmentShader = shader.fragmentShader.replace("#include <common>",`#include <common>varying vec3 tripPosition;varying vec3 tripNormal;vec3 blendNormal(vec3 normal){vec3 blending = abs( normal );blending = normalize(max(blending, 0.00001)); // Force weights to sum to 1.0 float b = (blending.x + blending.y + blending.z);blending /= vec3(b, b, b);return blending;}vec3 triplanarMapping (sampler2D tex, vec3 normal, vec3 position) {vec3 normalBlend = blendNormal(normal);vec3 xColor = texture(tex, position.yz).rgb;vec3 yColor = texture(tex, position.xz).rgb;vec3 zColor = texture(tex, position.xy).rgb;return (xColor * normalBlend.x + yColor * normalBlend.y + zColor * normalBlend.z);}`);shader.fragmentShader = shader.fragmentShader.replace("#include <map_fragment>",`#include <map_fragment>diffuseColor.rgb = vec3(triplanarMapping( map ,tripNormal,tripPosition));`);// shader.fragmentShader = shader.fragmentShader.replace(//     "#include <color_fragment>",//     `//     #include <color_fragment>//     diffuseColor.rgb = vec3(triplanar_mapping( map ,tripNormal,tripPosition,1.0));// `// );};
};

NodeMaterial

这是threejs新系统充满未来目前还没有一个完善的文档并且不太稳定 r132的时候支持这个材质 r138就被删除了一些api也都有变化可以先参考 https://raw.githack.com/sunag/three.js/dev-nodes-doc/docs/index.html#manual/en/introduction/How-to-use-node-material

import {MeshBasicNodeMaterial,texture,triplanarTexture,
} from "three/examples/jsm/nodes/Nodes.js";
import { nodeFrame } from "three/examples/jsm/renderers/webgl/nodes/WebGLNodes.js";const skyMat = new MeshBasicNodeMaterial();skyMat.colorNode = triplanarTexture(texture(this.helper.loadTexture("/public/textures/coral_stone_wall_diff_1k.jpg",(map) => {map.colorSpace = THREE.SRGBColorSpace;map.wrapS = THREE.RepeatWrapping;map.wrapT = THREE.RepeatWrapping;}))
);
skyMat.side = THREE.DoubleSide;const sky = new THREE.Mesh(new THREE.SphereGeometry(2, 32, 15), skyMat);
scene.add(sky);animation() {nodeFrame.update();
}

要注意每一次render 同时调用 nodeFrame.update(); 否则报错

骨骼材质特殊处理

这个问题需要根据three版本进行区别处理

r160版本使用的是 position
r155版本使用的是 nodeUniform2 * vec4( 忘了叫什么了, 1.0 )
总之每个版本可能不一样因为节点系统正在开发需要对应版本对应处理

r160版本写法如下

material.onBeforeCompile = (shader) => {material.vertexShader = shader.vertexShader.replace("#include <skinning_vertex>",`#include <skinning_vertex>nodeVarying2 = (modelMatrix * vec4(transformed,1.0)).xyz;`);
};

r155版本写法如下

material.onBeforeCompile = (shader) => {material.vertexShader = shader.vertexShader.replace("#include <skinning_vertex>",`#include <skinning_vertex>nodeVarying2 = ( nodeUniform2 * vec4( transformed, 1.0 ) );`);};