function Create_Worker(offscreencanvas) {
    return new Promise((resolve, reject) => {
        let data ="\n" +
            "var gl;\n" +
            "var rAFID;\n" +
            "var canvas;\n" +
            "var shaderProgram;\n" +
            "\n" +
            "function createProgram(){\n" +
            "    var vertCode =\n" +
            "        'attribute vec2 coordinates;' +\n" +
            "        'void main(void) {' + ' gl_Position = vec4(coordinates,0.0, 1.0);' + '}';\n" +
            "\n" +
            "//Create a vertex shader object\n" +
            "    var vertShader = gl.createShader(gl.VERTEX_SHADER);\n" +
            "\n" +
            "//Attach vertex shader source code\n" +
            "    gl.shaderSource(vertShader, vertCode);\n" +
            "\n" +
            "//Compile the vertex shader\n" +
            "    gl.compileShader(vertShader);\n" +
            "\n" +
            "//Fragment shader source code\n" +
            "    var fragCode = 'void main(void) {' + 'gl_FragColor = vec4(0.0, 0.0, 0.0, 0.1);' + '}';\n" +
            "\n" +
            "// Create fragment shader object\n" +
            "    var fragShader = gl.createShader(gl.FRAGMENT_SHADER);\n" +
            "\n" +
            "// Attach fragment shader source code\n" +
            "    gl.shaderSource(fragShader, fragCode);\n" +
            "\n" +
            "// Compile the fragment shader\n" +
            "    gl.compileShader(fragShader);\n" +
            "\n" +
            "// Create a shader program object to store combined shader program\n" +
            "    shaderProgram = gl.createProgram();\n" +
            "\n" +
            "// Attach a vertex shader\n" +
            "    gl.attachShader(shaderProgram, vertShader);\n" +
            "\n" +
            "// Attach a fragment shader\n" +
            "    gl.attachShader(shaderProgram, fragShader);\n" +
            "\n" +
            "// Link both programs\n" +
            "    gl.linkProgram(shaderProgram);\n" +
            "\n" +
            "// Use the combined shader program object\n" +
            "    gl.useProgram(shaderProgram);\n" +
            "}\n" +
            "\n" +
            "\n" +
            "function initbuffer(){\n" +
            "    var vertices = [-0.5, 0.5, -0.5, -0.5, 0.0, -0.5,];\n" +
            "\n" +
            "// Create a new buffer object\n" +
            "    var vertex_buffer = gl.createBuffer();\n" +
            "\n" +
            "// Bind an empty array buffer to it\n" +
            "    gl.bindBuffer(gl.ARRAY_BUFFER, vertex_buffer);\n" +
            "\n" +
            "// Pass the vertices data to the buffer\n" +
            "    gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertices), gl.STATIC_DRAW);\n" +
            "\n" +
            "// Unbind the buffer\n" +
            "    gl.bindBuffer(gl.ARRAY_BUFFER, null);\n" +
            "\n" +
            "    /* Step3: Create and compile Shader programs */\n" +
            "\n" +
            "// Vertex shader source code\n" +
            "\n" +
            "\n" +
            "    /* Step 4: Associate the shader programs to buffer objects */\n" +
            "\n" +
            "//Bind vertex buffer object\n" +
            "    gl.bindBuffer(gl.ARRAY_BUFFER, vertex_buffer);\n" +
            "\n" +
            "//Get the attribute location\n" +
            "    var coord = gl.getAttribLocation(shaderProgram, \"coordinates\");\n" +
            "\n" +
            "//point an attribute to the currently bound VBO\n" +
            "    gl.vertexAttribPointer(coord, 2, gl.FLOAT, false, 0, 0);\n" +
            "\n" +
            "//Enable the attribute\n" +
            "    gl.enableVertexAttribArray(coord);\n" +
            "\n" +
            "    /* Step5: Drawing the required object (triangle) */\n" +
            "\n" +
            "// Clear the canvas\n" +
            "    gl.clearColor(0.5, 0.5, 0.5, 0.9);\n" +
            "\n" +
            "// Enable the depth test\n" +
            "    gl.enable(gl.DEPTH_TEST);\n" +
            "\n" +
            "// Clear the color buffer bit\n" +
            "    gl.clear(gl.COLOR_BUFFER_BIT);\n" +
            "\n" +
            "}\n" +
            "\n" +
            "function draw() {\n" +
            "\n" +
            "// Set the view port\n" +
            "    gl.viewport(0, 0, canvas.width, canvas.height);\n" +
            "\n" +
            "// Draw the triangle\n" +
            "    gl.drawArrays(gl.TRIANGLES, 0, 3);\n" +
            "    rAFID = requestAnimationFrame(draw)\n" +
            "    console.log(\"draw\");\n" +
            "}\n" +
            "\n" +
            "\n" +
            "(function (root) {\n" +
            "    root.addEventListener(\"message\", function (e) {\n" +
            "        var message = e.data;\n" +
            "        switch (message.cmd) {\n" +
            "            case \"offscreencanvas\":\n" +
            "                canvas = message.data;\n" +
            "                gl = canvas.getContext('webgl');\n" +
            "                canvas.addEventListener(\"webglcontextlost\", (event) => {\n" +
            "                    console.log(\"webglcontextlost\", event);\n" +
            "                    if (rAFID) {\n" +
            "                        cancelAnimationFrame(this.rAFID);\n" +
            "                    }\n" +
            "                    event.preventDefault();\n" +
            "                }, false);\n" +
            "                canvas.addEventListener(\"webglcontextrestored\", (event) => {\n" +
            "                    console.log(\"webglcontextrestored\", event);\n" +
            "                    gl = canvas.getContext('webgl');\n" +
            "                    createProgram();\n" +
            "                    initbuffer();\n" +
            "                    rAFID = requestAnimationFrame(draw);\n" +
            "                }, false);\n" +
            "                createProgram();\n" +
            "                initbuffer();\n" +
            "                rAFID = requestAnimationFrame(draw);\n" +
            "                break;\n" +
            "        }\n" +
            "    });\n" +
            "})(self);\n"
        workerhandle = new Worker(window.URL.createObjectURL(new Blob([data])));
        let postdata = {
            cmd:"offscreencanvas",
            data:offscreencanvas
        };
        workerhandle.postMessage(postdata, [postdata.data])
        workerhandle.onmessage = function (e) {
            let message = e.data;
            switch (message.cmd) {
                case "ok":
                    resolve();
                    break;
            }
        }
    })
}