Created
October 29, 2019 18:15
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Hardware Overlay Demo
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| <!DOCTYPE html> | |
| <meta charset="utf-8"> | |
| <meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1, user-scalable=0"> | |
| <title>Hardware Overlay Demo</title> | |
| <script> | |
| window.addEventListener('DOMContentLoaded', () => { | |
| const canvas = document.querySelector('canvas'); | |
| const gl = canvas.getContext('webgl', {desynchronized: true}); | |
| canvas.width = 300 * devicePixelRatio; | |
| canvas.height = 150 * devicePixelRatio; | |
| gl.clearColor(1, 1, 1, 1); | |
| gl.clear(gl.COLOR_BUFFER_BIT); | |
| gl.scissor(150, 75, 300, 150); | |
| gl.enable(gl.SCISSOR_TEST); | |
| let hue = 0; | |
| const raf = () => { | |
| hue += 1; | |
| r = Math.sin(0.05 * hue + 0) * 127 + 128; | |
| g = Math.sin(0.05 * hue + 2) * 127 + 128; | |
| b = Math.sin(0.05 * hue + 4) * 127 + 128; | |
| gl.clearColor(r / 255, g / 255, b / 255, 1); | |
| gl.clear(gl.COLOR_BUFFER_BIT); | |
| gl.flush(); | |
| requestAnimationFrame(raf); | |
| }; | |
| requestAnimationFrame(raf); | |
| const setSizeAndRotation = () => { | |
| const angle = screen.orientation.angle; | |
| canvas.style.transform = `rotateZ(${angle}deg)`; | |
| if (angle % 180 == 90) { | |
| canvas.style.width = '150px'; | |
| canvas.style.height = '300px'; | |
| canvas.style.left = '75px'; | |
| canvas.style.top = '-75px'; | |
| canvas.width = 150 * devicePixelRatio; | |
| canvas.height = 300 * devicePixelRatio; | |
| } else { | |
| canvas.style.width = '300px'; | |
| canvas.style.height = '150px'; | |
| canvas.style.left = '0px'; | |
| canvas.style.top = '0px'; | |
| canvas.width = 300 * devicePixelRatio; | |
| canvas.height = 150 * devicePixelRatio; | |
| } | |
| gl.disable(gl.SCISSOR_TEST); | |
| gl.clearColor(1, 1, 1, 1); | |
| gl.clear(gl.COLOR_BUFFER_BIT); | |
| gl.flush(); | |
| angle % 180 == 90 ? gl.scissor(75, 150, 150, 300) | |
| : gl.scissor(150, 75, 300, 150); | |
| gl.enable(gl.SCISSOR_TEST); | |
| }; | |
| screen.orientation.addEventListener('change', setSizeAndRotation); | |
| setSizeAndRotation(); | |
| }); | |
| </script> | |
| <style> | |
| .container { | |
| padding: 25px; | |
| position: relative; | |
| } | |
| canvas { | |
| position: absolute; | |
| width: 300px; | |
| height: 150px; | |
| left: 0px; | |
| top: 0px; | |
| } | |
| </style> | |
| <div class="container"> | |
| <canvas></canvas> | |
| </div> |
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