WebGL之点上添加图片(using texture on point)

本文介绍了一种使用WebGL进行纹理点绘制的技术实现方法。通过加载图像作为纹理,并将其应用于点绘制中,使得每个点都能显示为具有纹理效果的小图片。文章详细展示了顶点着色器和片段着色器的编写过程,以及如何设置WebGL上下文和加载图像。

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var VSHADER_SOURCE =[    
        "attribute vec4 a_Position;",                            
        "uniform mat4 u_ProjMatrix;",
        "uniform float u_PointSize;",
        "void main() {",
            "    gl_PointSize = u_PointSize;",
            "    gl_Position = u_ProjMatrix * a_Position;",
        "}"

    ].join("\n")
var FSHADER_SOURCE =
[
        "precision mediump float;",    
        "uniform sampler2D u_Sampler;",               
        "void main() {",     
     "  gl_FragColor = texture2D(u_Sampler,vec2(gl_PointCoord.x,1.0 - gl_PointCoord.y));",
"}" ].join("\n") function main() { var canvas = document.getElementById('webgl'); var gl = getWebGLContext(canvas); if (!gl) { console.log('Failed to get the rendering context for WebGL'); return; } if (!initShaders(gl, VSHADER_SOURCE, FSHADER_SOURCE)) { console.log('Failed to intialize shaders.'); return; } var projMatrix4=new Matrix4(); projMatrix4.setOrtho(-1,1,-1,1,0.0,1.0); var u_projMatrix=gl.getUniformLocation(gl.program,'u_ProjMatrix'); gl.uniformMatrix4fv(u_projMatrix,false,projMatrix4.elements); var position=gl.getAttribLocation(gl.program,'a_Position'); gl.vertexAttrib3f(position,0.0,0.0,0.0); gl.clearColor(0, 0, 0, 1); gl.clear(gl.COLOR_BUFFER_BIT); loadImg(gl); } function loadImg(gl){ var image=new Image(); image.onload=function(){ drawPic(gl,image) } image.src="pic.png"; } function drawPic(gl,image){ var width=image.width; var height=image.height; var pointSize=gl.getUniformLocation(gl.program,"u_PointSize"); gl.uniform1f(pointSize,Math.max(width,height)); var texture=gl.createTexture(); //gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL,1); gl.activeTexture(gl.TEXTURE0); gl.bindTexture(gl.TEXTURE_2D,texture); gl.texParameteri(gl.TEXTURE_2D,gl.TEXTURE_MAG_FILTER,gl.NEAREST); gl.texParameteri(gl.TEXTURE_2D,gl.TEXTURE_MIN_FILTER,gl.NEAREST); gl.texParameteri(gl.TEXTURE_2D,gl.TEXTURE_WRAP_S,gl.CLAMP_TO_EDGE); gl.texParameteri(gl.TEXTURE_2D,gl.TEXTURE_WRAP_T,gl.CLAMP_TO_EDGE); gl.uniform1i(gl.getUniformLocation(gl.program,"u_Sampler"),0); gl.texImage2D(gl.TEXTURE_2D,0,gl.RGBA,gl.RGBA,gl.UNSIGNED_BYTE,image); gl.clear(gl.COLOR_BUFFER_BIT); gl.drawArrays(gl.POINTS,0,1); gl.bindTexture(gl.TEXTURE_2D, null); }

 

转载于:https://www.cnblogs.com/wema/p/7084835.html

<!DOCTYPE html> <html lang="en"> <head> <title>Load Obj and Mtl file with texture using Three.js</title> <meta charset="utf-8"> <meta name="viewport" content="width=device-width, initial-scale=1"> <style> body { margin: 0; overflow: hidden; } canvas { width: 100%; height: 100%; } </style> </head> <body> <script src="https://cdn.jsdelivr.net/npm/three@0.131.2/build/three.min.js"></script> <script src="https://cdn.jsdelivr.net/npm/three@0.131.2/examples/js/loaders/MTLLoader.js"></script> <script src="https://cdn.jsdelivr.net/npm/three@0.131.2/examples/js/loaders/OBJLoader.js"></script> <script> // 创建场景、相机、光源等 var scene = new THREE.Scene(); var camera = new THREE.PerspectiveCamera(75, window.innerWidth / window.innerHeight, 0.1, 1000); camera.position.set(0, 0, 5); var light = new THREE.PointLight(0xffffff, 1, 100); light.position.set(0, 1, 5); scene.add(light); // 加载模型 var mtlLoader = new THREE.MTLLoader(); mtlLoader.load('s/file.mtl', function(materials) { materials.preload(); var objLoader = new THREE.OBJLoader(); objLoader.setMaterials(materials); objLoader.load('s/file.obj', function(object) { // 加载完成后,设置材质、纹理等 object.traverse(function(child) { if (child instanceof THREE.Mesh) { // child.material.map = new THREE.TextureLoader().load('s/texture.jpg'); child.material.needsUpdate = true; } }); // 加入到场景中 scene.add(object); }); }); // 创建渲染器 var renderer = new THREE.WebGLRenderer(); renderer.setSize(window.innerWidth, window.innerHeight); document.body.appendChild(renderer.domElement); // 渲染场景 function animate() { requestAnimationFrame(animate); renderer.render(scene, camera); } animate(); </script> </body> </html>
06-09
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