31:[] 2f:{"title":"WebGL Checks","cells":[{"id":0,"value":"md`# WebGL Checks`","pinned":false,"hidden":false,"mode":"ojs"},{"id":62,"value":"md`Check if webgl is supported, and if so which extensions are supported:`","pinned":false,"hidden":false,"mode":"ojs"},{"id":7,"value":"gl = {\n var gl;\n const canvas = document.createElement('canvas');\n \n try { gl = canvas.getContext(\"webgl\"); }\n catch (x) { gl = null; }\n\n if (gl == null) {\n try { gl = canvas.getContext(\"experimental-webgl\"); }\n catch (x) { gl = null; }\n }\n return gl;\n}","pinned":true,"hidden":false,"mode":"ojs"},{"id":9,"value":"webgl_supported = gl ? true : false","pinned":true,"hidden":false,"mode":"ojs"},{"id":18,"value":"function extension_available(extension_string) {\n if (webgl_supported) {\n return gl.getSupportedExtensions().includes(extension_string)\n }\n}","pinned":true,"hidden":false,"mode":"ojs"},{"id":152,"value":"mutable has_webgl_context = true;","pinned":true,"hidden":false,"mode":"ojs"},{"id":150,"value":"function add_context_listener(gl) {\n gl.canvas.addEventListener(\"webglcontextlost\", (e) => {\n mutable has_webgl_context = false;\n }, false);\n}","pinned":true,"hidden":false,"mode":"ojs"},{"id":161,"value":"md`Note – This approach to detecting context loss assumes you're only listening to a single context in your notebook (since we're modifying a single global flag \\`\\`has_webgl_context\\`\\`). Could be generalized.\n\nShould also reset this flag is context is restored (if we provide a way to do this without reloading the page).`","pinned":false,"hidden":false,"mode":"ojs"},{"id":137,"value":"webgl_not_supported_message = `

Sorry, WebGL is not supported on your device.

`","pinned":false,"hidden":false,"mode":"ojs"},{"id":139,"value":"html`${webgl_not_supported_message}`","pinned":false,"hidden":false,"mode":"ojs"},{"id":145,"value":"function error_message(e) {\n return`

The following error occurred:

${e}

Please refresh the page to try loading the graphic again.

`\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":143,"value":"html`${error_message(\"Lost WebGL Context\")}`","pinned":false,"hidden":false,"mode":"ojs"}],"files":"$W31","stdlib":"1","titling":"auto"}