javascript-Safari中的HTML5视频纹理
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内容图文
是否可以在Safari中将视频用作webGL的纹理(我什至没有在讲iOS Safari)？我无法使其工作.这是我想出的最简单的代码：https://jsfiddle.net/bmkb6r9h/3/也不起作用here.
一旦视频源来自另一个域或子域,并且出现SecurityError：DOM异常18,它就会失败：尝试在将视频纹理附加到texImage2D时突破用户代理的安全策略.
这是我的代码(很抱歉,它有点长,但这是webGL的工作方式),也很高兴就如何改进webGL提出意见.我从https://github.com/hawksley/eleVR-Web-Player那里获取了代码,它是360视频播放器的绝佳介绍.
// get DOM elements
videoContainer = document.getElementById('video-container');
video = document.getElementById('video');
canvas = document.getElementById('glcanvas');
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;
// load the video, and play on ready
video.load();
video.oncanplaythrough = function() {
video.play();
drawScene();
};
gl = canvas.getContext("webgl") || canvas.getContext("experimental-webgl");
// create and attach the shader program to the webGL context
var attributes, uniforms, program;
var attachShader = function(params) {
// compile the shaders from the shaders scripts
var getShaderByName = function(id) {
var shaderScript = document.getElementById(id);
var theSource = "";
var currentChild = shaderScript.firstChild;
while(currentChild) {
if (currentChild.nodeType === 3) {
theSource += currentChild.textContent;
}
currentChild = currentChild.nextSibling;
}
var result;
if (shaderScript.type === "x-shader/x-fragment") {
result = gl.createShader(gl.FRAGMENT_SHADER);
} else {
result = gl.createShader(gl.VERTEX_SHADER);
}
gl.shaderSource(result, theSource);
gl.compileShader(result);
if (!gl.getShaderParameter(result, gl.COMPILE_STATUS)) {
alert("An error occurred compiling the shaders: " + gl.getShaderInfoLog(result));
return null;
}
return result;
};
fragmentShader = getShaderByName(params.fragmentShaderName);
vertexShader = getShaderByName(params.vertexShaderName);
program = gl.createProgram();
gl.attachShader(program, vertexShader);
gl.attachShader(program, fragmentShader);
gl.linkProgram(program);
if (!gl.getProgramParameter(program, gl.LINK_STATUS)) {
alert("Unable to initialize the shader program: " + gl.getProgramInfoLog(program));
}
gl.useProgram(program);
// get the location of attributes and uniforms
attributes = {};
for (var i = 0; i < params.attributes.length; i++) {
var attributeName = params.attributes[i];
attributes[attributeName] = gl.getAttribLocation(program, attributeName);
gl.enableVertexAttribArray(attributes[attributeName]);
}
uniforms = {};
for (i = 0; i < params.uniforms.length; i++) {
var uniformName = params.uniforms[i];
uniforms[uniformName] = gl.getUniformLocation(program, uniformName);
gl.enableVertexAttribArray(attributes[uniformName]);
}
};
attachShader({
fragmentShaderName: 'shader-fs',
vertexShaderName: 'shader-vs',
attributes: ['aVertexPosition'],
uniforms: ['uSampler'],
});
// some webGL initialization
gl.clearColor(0.0, 0.0, 0.0, 0.0);
gl.clearDepth(1.0);
gl.disable(gl.DEPTH_TEST);
positionsBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, positionsBuffer);
var positions = [
-1.0, -1.0,
1.0, -1.0,
1.0, 1.0,
-1.0, 1.0,
];
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(positions), gl.STATIC_DRAW);
verticesIndexBuffer = gl.createBuffer();
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, verticesIndexBuffer);
var vertexIndices = [
0, 1, 2, 0, 2, 3,
];
gl.bufferData(gl.ELEMENT_ARRAY_BUFFER,
new Uint16Array(vertexIndices), gl.STATIC_DRAW);
texture = gl.createTexture();
gl.bindTexture(gl.TEXTURE_2D, texture);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);
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.bindTexture(gl.TEXTURE_2D, null);
// update the texture from the video
updateTexture = function() {
gl.bindTexture(gl.TEXTURE_2D, texture);
gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, true);
// the next line fails in Safari if the video is coming from another domain or subdomain
gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGB, gl.RGB,
gl.UNSIGNED_BYTE, video);
gl.bindTexture(gl.TEXTURE_2D, null);
};
// draw stuff in the canvas
drawScene = function() {
updateTexture();
gl.useProgram(program);
gl.bindBuffer(gl.ARRAY_BUFFER, positionsBuffer);
gl.vertexAttribPointer(attributes['aVertexPosition'], 2, gl.FLOAT, false, 0, 0);
// Specify the texture to map onto the faces.
gl.activeTexture(gl.TEXTURE0);
gl.bindTexture(gl.TEXTURE_2D, texture);
gl.uniform1i(uniforms['uSampler'], 0);
// Draw
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, verticesIndexBuffer);
gl.drawElements(gl.TRIANGLES, 6, gl.UNSIGNED_SHORT, 0);
// keep looping
requestAnimationFrame(drawScene);
};<!-- Fragmend shader program -->
<script id="shader-fs" type="x-shader/x-fragment">
varying mediump vec2 vDirection;
uniform sampler2D uSampler;
void main(void) {
gl_FragColor = texture2D(uSampler, vec2(vDirection.x * 0.5 + 0.5, vDirection.y * 0.5 + 0.5));
}
</script>
<!-- Vertex shader program -->
<script id="shader-vs" type="x-shader/x-vertex">
attribute mediump vec2 aVertexPosition;
varying mediump vec2 vDirection;
void main(void) {
gl_Position = vec4(aVertexPosition, 1.0, 1.0) * 2.0;
vDirection = aVertexPosition;
}
</script>
<div id="video-container" style="width: 100vw; height: 100vh;">
<canvas id="glcanvas"></canvas>
<video preload="auto" id="video" loop="true" webkit-playsinline crossOrigin="anonymous" style=" width: 300px; height: 200px;" controls>
<source src="http://vjs.zencdn.net/v/oceans.mp4" type="video/mp4">
</video>
</div>在Chrome / Firefox中,一切运行正常.
解决方法:
这是Safari中的错误. Safari尚不支持视频的CORS(跨源支持).参见this webkit bug.
Video does work in WebGL in Safari if the video is from the same origin.
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