<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>WebGL</title>
<script src="glMatrix-0.9.5.min.js"></script>
<script id="shader-vs" type="x-shader/x-vertex">
attribute vec3 aVertexPosition;
attribute vec2 inUV;
uniform mat4 proj;
varying vec2 outUV;
void main(void) {
gl_Position = proj * vec4(aVertexPosition, 1.0);
outUV = inUV;
}
</script>
<script id="shader-fs" type="x-shader/x-fragment">
precision mediump float;
uniform sampler2D u_Sampler0;
uniform sampler2D u_Sampler1;
varying vec2 outUV;
void main(void) {
vec4 color0 = texture2D(u_Sampler0, outUV);
vec4 color1 = texture2D(u_Sampler1, outUV);
gl_FragColor = color0 * color1;
}
</script>
<script>
var gl;
var canvas;
var shaderProgram;
var vertexBuffer;
var image0Loaded = false;
var image1Loaded = false;
var projectMat = mat4.create()
function createGLContext(canvas) {
var names = ["webgl", "experimental-webgl"];
var context = null;
for (var i = 0; i < names.length; i++) {
try {
context = canvas.getContext(names[i]);
} catch (e) { }
if (context) {
break;
}
}
if (context) {
context.viewportWidth = canvas.width;
context.viewportHeight = canvas.height;
} else {
alert("Failed to create WebGL context!");
}
return context;
}
function loadShaderFromDOM(id) {
var shaderScript = document.getElementById(id);
if (!shaderScript) {
return null;
}
var shaderSource = "";
var currentChild = shaderScript.firstChild;
while (currentChild) {
if (currentChild.nodeType == 3) { // 3 corresponds to TEXT_NODE
shaderSource += currentChild.textContent;
}
currentChild = currentChild.nextSibling;
}
mat4.ortho(0,canvas.clientWidth,canvas.clientHeight,0,-1000.0,+1000.0,projectMat)
var shader;
if (shaderScript.type == "x-shader/x-fragment") {
shader = gl.createShader(gl.FRAGMENT_SHADER);
} else if (shaderScript.type == "x-shader/x-vertex") {
shader = gl.createShader(gl.VERTEX_SHADER);
} else {
return null;
}
gl.shaderSource(shader, shaderSource);
gl.compileShader(shader);
if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
alert(gl.getShaderInfoLog(shader));
return null;
}
return shader;
}
function setupShaders() {
vertexShader = loadShaderFromDOM("shader-vs");
fragmentShader = loadShaderFromDOM("shader-fs");
shaderProgram = gl.createProgram();
gl.attachShader(shaderProgram, vertexShader);
gl.attachShader(shaderProgram, fragmentShader);
gl.linkProgram(shaderProgram);
if (!gl.getProgramParameter(shaderProgram, gl.LINK_STATUS)) {
alert("Failed to setup shaders");
}
gl.useProgram(shaderProgram);
shaderProgram.vertexPositionAttribute = gl.getAttribLocation(shaderProgram, "aVertexPosition");
shaderProgram.projUniform = gl.getUniformLocation(shaderProgram, "proj");
shaderProgram.uniformTexture = gl.getUniformLocation(shaderProgram, "u_Sampler0");
shaderProgram.uniformTexture1 = gl.getUniformLocation(shaderProgram, "u_Sampler1");
shaderProgram.attrUA = gl.getAttribLocation(shaderProgram, "inUV");
}
function setupBuffers() {
vertexBuffer = gl.createBuffer();
var jsArrayData = [
100,100,0,0.0,0.0,
400,100,0,1.0,0.0,
400,400,0,1.0,1.0,
100,100,0,0.0,0.0,
400,400,0,1.0,1.0,
100,400,0,0.0,1.0,
]
gl.bindBuffer(gl.ARRAY_BUFFER, vertexBuffer);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(jsArrayData), gl.STATIC_DRAW);
}
function draw() {
gl.clearColor(0.0, 0.0, 0.0, 1.0);
gl.viewport(0, 0, gl.viewportWidth, gl.viewportHeight);
gl.uniformMatrix4fv(shaderProgram.projUniform,false,projectMat)
gl.vertexAttribPointer(shaderProgram.vertexPositionAttribute,3,gl.FLOAT,false,4*5,0)
gl.vertexAttribPointer(shaderProgram.attrUA,2,gl.FLOAT,false,4*5,12)
gl.enableVertexAttribArray(shaderProgram.vertexPositionAttribute);
gl.enableVertexAttribArray(shaderProgram.attrUA);
textureHandle = gl.createTexture()
var image = new Image()
image.src = 'img/3.png'
image.onload = function (){
gl.activeTexture(gl.TEXTURE0)
gl.bindTexture(gl.TEXTURE_2D,textureHandle)
gl.texImage2D(gl.TEXTURE_2D,0,gl.RGBA,gl.RGBA,gl.UNSIGNED_BYTE,image)
gl.texParameteri(gl.TEXTURE_2D,gl.TEXTURE_MIN_FILTER,gl.NEAREST)
gl.uniform1i(shaderProgram.uniformTexture,0)
console.log("第一张")
}
var image1 = new Image()
image1.src = 'img/1.png'
image1.onload = function (){
gl.activeTexture(gl.TEXTURE1)
gl.bindTexture(gl.TEXTURE_2D,textureHandle)
gl.texImage2D(gl.TEXTURE_2D,0,gl.RGBA,gl.RGBA,gl.UNSIGNED_BYTE,image1)
gl.texParameteri(gl.TEXTURE_2D,gl.TEXTURE_MIN_FILTER,gl.NEAREST)
gl.uniform1i(shaderProgram.uniformTexture1,1)
gl.clear(gl.COLOR_BUFFER_BIT);
gl.drawArrays(gl.TRIANGLES,0,6)
}
}
function startup() {
canvas = document.getElementById("myGLCanvas");
gl = createGLContext(canvas);
setupShaders();
setupBuffers();
draw();
}
</script>
</head>
<body onload="startup()">
<canvas id="myGLCanvas" width="640" height="480"></canvas>
</body>
</html>
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