{"id":412,"date":"2016-04-10T00:23:47","date_gmt":"2016-04-09T16:23:47","guid":{"rendered":"https:\/\/blog.dimension.moe\/?p=412"},"modified":"2017-09-18T20:10:49","modified_gmt":"2017-09-18T12:10:49","slug":"more-flexible-way-to-draw-a-point","status":"publish","type":"post","link":"https:\/\/archive.ntzyz.io\/2016\/04\/10\/more-flexible-way-to-draw-a-point\/","title":{"rendered":"[WebGL] \u66f4\u52a0\u7075\u6d3b\u7684\u63cf\u70b9\u5b9e\u73b0"},"content":{"rendered":"<style type=\"text\/css\">\np.indent {text-indent: 2em;margin-top: 0.75em; margin-bottom: 0.75em;}\n<\/style>\n<p class=\"indent\">\u4e4b\u524d\u7684\u4ee3\u7801\u5b9e\u73b0\u4e86\u63cf\u7ed8\u4e00\u4e2a\u5de8\u5927\u7684\u3001\u6b63\u65b9\u5f62\u7684\u3001\u7ea2\u8272\u7684\u70b9\uff0c\u4f46\u662f\uff0c\u7a0d\u6709\u5e38\u8bc6\u7684\u4eba\u90fd\u80fd\u770b\u51fa\uff0c\u90a3\u4e2a\u70b9\u7684\u989c\u8272\u3001\u4f4d\u7f6e\u3001\u5927\u5c0f\uff0c\u90fd\u662f\u65e0\u6cd5\u5728\u8fd0\u884c\u65f6\u6539\u53d8\u7684\uff0c\u8fd9\u5c31\u6bd4\u8f83\u5c34\u5c2c\u4e86\u2026\u2026<\/p>\n<p class=\"indent\">\u6beb\u65e0\u7591\u95ee\uff0cWeb \u524d\u7aef\u7684\u7f16\u7a0b\u8bed\u8a00\u662f ECMAScript\uff0c\u7136\u800c\u9876\u70b9\u7740\u8272\u5668\u548c\u7247\u5143\u7740\u8272\u5668\u7684\u63a7\u5236\u7528\u7684\u5374\u662f GLSL ES\u3002\u4e3a\u4e86\u80fd\u52a8\u6001\u7684\u4fee\u6539\u7740\u8272\u5668\u4ee3\u7801\uff0c\u6211\u4eec\u5c31\u9700\u8981\u5728\u7740\u8272\u5668\u4ee3\u7801\u91cc\u6dfb\u52a0\u9700\u8981\u52a8\u6001\u7f16\u8f91\u7684\u53d8\u91cf\uff0c\u5e76\u4e14\u901a\u8fc7\u5df2\u6709\u7684\u65b9\u6cd5\u6765\u901a\u8fc7 JavaScript \u83b7\u53d6\u5e76\u4fee\u6539\u4ed6\u4eec\u7684\u503c\u3002<\/p>\n<p><!--more--><\/p>\n<p class=\"indent\">\u4e0e\u4e4b\u524d\u76f8\u540c\uff0c\u6211\u4eec\u9700\u8981\u4e00\u4e2a\u5177\u6709 canvas \u7684\u7f51\u9875\uff0c\u5176 ID \u4e3a webgl\u3002\u6b64\u5904 HTML \u4ee3\u7801\u53ef\u4ee5\u76f4\u63a5\u53c2\u8003\u4e4b\u524d\u7684\u3002\u540c\u6837\u6211\u4eec\u4e5f\u9700\u8981\u83b7\u53d6 WebGL \u4e0a\u4e0b\u6587\uff0c\u8fd9\u4e9b\u4ee3\u7801\u4e5f\u662f\u548c\u4e4b\u524d\u4e00\u81f4\u7684\uff1a<\/p>\n<pre class=\"lang:javascript\">\tvar canvas = document.getElementById('webgl');\r\n\tvar gl = getWebGLContext(canvas);\r\n\r\n\tif (!gl) {\r\n\t\tconsole.log('Error on getting context of WebGL');\r\n\t\treturn;\r\n\t}\r\n<\/pre>\n<p class=\"indent\">\u6211\u4eec\u9700\u8981\u5728\u7740\u8272\u5668\u4ee3\u7801\u4e2d\u6dfb\u52a0\u76f8\u5e94\u7684\u53d8\u91cf\u3002\u5176\u4e2d\uff0c\u9876\u70b9\u7740\u8272\u5668\u9700\u8981\u7528 attribute \u4fee\u9970\u7b26\uff0c\u662f\u4e00\u4e2a\u56db\u7ef4\u5411\u91cf\uff0c\u800c\u7247\u5143\u7740\u8272\u5668\u5219\u662f\u4f7f\u7528\u7684 uniform \u4fee\u9970\u7b26\uff0c\u540c\u6837\u4e5f\u662f\u4e00\u4e2a\u56db\u7ef4\u5411\u91cf\u3002\u7247\u5143\u7740\u8272\u5668\u91cc\u7684\u7b2c\u4e00\u884c precision mediump float; \u6307\u660e\u4e86\u6570\u636e\u7cbe\u5ea6\uff1a<\/p>\n<pre class=\"lang:javascript\">\tvar VSHADER_SOURCE =\r\n\t\t'attribute vec4 a_Position;\\n' +\r\n\t\t'void main() {\\n' +\r\n\t\t'    gl_Position = a_Position;\\n' +\r\n\t\t'    gl_PointSize = 10.0;\\n' +\r\n\t\t'}\\n';\r\n\tvar FSHADER_SOURCE =\r\n\t\t'precision mediump float;\\n' + \r\n\t\t'uniform vec4 u_FragColor;\\n' + \r\n\t\t'void main() {\\n' +\r\n\t\t'    gl_FragColor = u_FragColor;\\n' +\r\n\t\t'}\\n';\r\n<\/pre>\n<p class=\"indent\">\u521d\u59cb\u5316\u8fd9\u4e24\u4e2a\u7740\u8272\u5668\u3002\u5176\u5b9e\u8fd9\u91cc\u7684\u5de5\u4f5c\u4e0d\u662f\u8c03\u7528\u4e00\u4e2a\u51fd\u6570\u8fd9\u4e48\u7b80\u5355\u3002initShaders \u51fd\u6570\u662f\u6211\u4f7f\u7528\u7684\u53c2\u8003\u4e66\u4e2d\u7684\u5e93\u63d0\u4f9b\u7684\uff0c\u7a0d\u5fae\u770b\u4e86\u4e0b\u4ee3\u7801\uff0c\u4f3c\u4e4e\u6d89\u53ca\u4e86 shader \u7684\u7f16\u8bd1\u4e0e\u94fe\u63a5\uff0c\u8fd8\u6709\u7a0b\u5e8f\u5bf9\u8c61\u7684\u751f\u6210\u7b49\u5185\u5bb9\u3002\u6309\u7167\u4e66\u672c\u7684\u610f\u601d\uff0c\u8fd9\u4e9b\u7ec6\u8282\u90fd\u4f1a\u5728\u540e\u9762\u8be6\u7ec6\u8bf4\u660e\uff0c\u8fd9\u91cc\u6211\u4e5f\u4e0d\u53bb\u5173\u6ce8\u4ed6\u4eec\u4e86\u3002<\/p>\n<pre class=\"lang:javascript\">\tif (!initShaders(gl, VSHADER_SOURCE, FSHADER_SOURCE)) {\r\n\t\tconsole.log('Error on initialize shaders.');\r\n\t\treturn;\r\n\t}\r\n<\/pre>\n<p class=\"indent\">\u55ef\u2026\u2026\u63a5\u7740\u5c31\u662f\u4f7f\u7528 WebGL \u63d0\u4f9b\u7684 getAttribLocation \u51fd\u6570\u548c getUniformLocation \u51fd\u6570\uff0c\u6765\u83b7\u5f97\u90a3\u4e24\u4e2a\u53d8\u91cf\u7684\u4f4d\u7f6e\u3002\u5f53\u83b7\u5f97\u4f4d\u7f6e\u51fa\u73b0\u9519\u8bef\u65f6\uff0c\u51fd\u6570\u5c06\u8fd4\u56de\u4e00\u4e2a\u8d1f\u503c\uff1a<\/p>\n<pre class=\"lang:javascript\">\tvar a_Position = gl.getAttribLocation(gl.program, 'a_Position');\r\n\tif (a_Position < 0) {\r\n\t\tconsole.log('Error on getting the storage location of a_Position');\r\n\t\treturn;\r\n\t}\r\n\tvar u_FragColor = gl.getUniformLocation(gl.program, 'u_FragColor');\r\n\tif (u_FragColor < 0) {\r\n\t\tconsole.log('Error on getting the storage location of u_FragColor');\r\n\t\treturn;\r\n\t}\r\n<\/pre>\n<p class=\"indent\">\u8fd9\u6837\u4e0b\u6765\uff0c\u6211\u4eec\u5c31\u53ef\u4ee5\u76f4\u63a5\u7684\u8c03\u7528 gl.vertexAttrib3f \u65b9\u6cd5\u548c gl.uniform4f \u65b9\u6cd5\uff0c\u6765\u52a8\u6001\u7684\u4fee\u6539\u4e24\u4e2a\u7740\u8272\u5668\u7684\u5185\u5bb9\u3002\u4e3a\u4e86\u4f53\u73b0\u51fa\u52a8\u6001\uff0c\u505a\u4e00\u4e2a\u70b9\u5230\u54ea\u513f\u753b\u5230\u54ea\u513f\u7684\u9875\u9762\uff0c\u65e0\u7591\u662f\u6700\u7b80\u660e\u7684\u4e86\u3002<\/p>\n<p class=\"indent\">\u56e0\u4e3a\u6d89\u53ca\u5230\u4e86\u591a\u4e2a\u70b9\u7684\u5b58\u50a8\uff0c\u6211\u4eec\u9700\u8981\u65b0\u589e\u52a0\u4e00\u4e2a\u53d8\u91cf\u6765\u4fdd\u5b58\u5df2\u7ecf\u5355\u51fb\u8fc7\u7684\u70b9\u7684\u4f4d\u7f6e\uff0c\u5728 app.js \u6700\u5f00\u5934\u589e\u52a0\u4e00\u884c\uff1a<\/p>\n<pre class=\"lang:javascript\">\tvar points = new Array();<\/pre>\n<p class=\"indent\">\u7136\u540e\u518d\u5199\u4e00\u4e2a\u51fd\u6570\uff0c\u6765\u63cf\u7ed8 points \u6570\u7ec4\u5185\u7684\u6240\u6709\u7684\u70b9\u3002\u5176\u4e2d\uff0c\u53f3\u4e0a\u3001\u5de6\u4e0a\u3001\u5de6\u4e0b\u3001\u53f3\u4e0b\u7684\u70b9\u7684\u989c\u8272\u4f9d\u6b21\u4e3a\u7ea2\u3001\u7eff\u3001\u84dd\u3001\u767d\u3002<\/p>\n<pre class=\"lang:javascript\">\tfunction drawPoints() {\r\n\t\tgl.clearColor(0, 0 , 0, 1);\r\n\t\tgl.clear(gl.COLOR_BUFFER_BIT);\r\n\t\tfor (var i = 0; i != points.length; ++i) {\r\n\t\t\tgl.vertexAttrib3f(a_Position, points[i].x, points[i].y, 0.0);\r\n\t\t\tif (points[i].x > 0 && points[i].y > 0)\r\n\t\t\t\tgl.uniform4f(u_FragColor, 1, 0, 0, 1);\r\n\t\t\telse if (points[i].x < 0 &#038;&#038; points[i].y < 0)\r\n\t\t\t\tgl.uniform4f(u_FragColor, 0, 0, 1, 1);\r\n\t\t\telse if (points[i].x < 0)\r\n\t\t\t\tgl.uniform4f(u_FragColor, 0, 1, 0, 1);\r\n\t\t\telse\r\n\t\t\t\tgl.uniform4f(u_FragColor, 1, 1, 1, 1);\r\n\t\t\tgl.drawArrays(gl.POINT, 0, 1);\r\n\t\t}\r\n\t};<\/pre>\n<p class=\"indent\">\u70b9\u7684\u4f4d\u7f6e\u6765\u6e90\u53ef\u4ee5\u901a\u8fc7\u589e\u52a0\u4e00\u4e2a\u5bf9 canvas \u7684 click \u4e8b\u4ef6\u7684\u76d1\u542c\uff0c\u5c06\u83b7\u5f97\u7684\u4fe1\u606f\u8f6c\u6362\u540e push \u5230 points \u4e2d\u3002\u8fd9\u91cc\u9700\u8981\u6ce8\u610f\u7684\u5c31\u662f HTML \u5750\u6807\u4e0e GL \u5750\u6807\u7684\u8f6c\u6362\u3002\u8bf4\u8d77\u6765\u6211\u8fd8\u6ca1\u8bf4 WebGL \u7684\u9ed8\u8ba4\u5750\u6807\u7cfb\u5462\uff08\u8eba<\/p>\n<p class=\"indent\">\u60f3\u4e86\u60f3\u611f\u89c9\u8fd8\u662f\u6ca1\u5565\u597d\u8bf4\u7684\uff0c\u968f\u624b\u7cca\u4e24\u5f20\u56fe\u5e94\u8be5\u5c31\u90fd\u80fd\u7406\u89e3\u4e86\u2026\u2026\u5427<\/p>\n<div style=\"background-color: rgba(255, 255, 255, 0.7); display: inline-block;\">\n<img loading=\"lazy\" width=\"800\" height=\"400\" src=\"https:\/\/blog.dimension.moe\/wp-content\/uploads\/\u540d\u7a31\u672a\u8a2d\u5b9a-1.png\" alt=\"\u540d\u7a31\u672a\u8a2d\u5b9a 1\"class=\"aligncenter size-full wp-image-416\" \/>\n<\/div>\n<p class=\"indent\"><del>\u8bf7\u53eb\u6211\u7075\u9b42\u753b\u5e08<\/del><\/p>\n<p class=\"indent\">\u7136\u540e\u5c31\u662f\u4ee3\u7801\u4e86\uff0c\u7406\u89e3\u4e86\u5750\u6807\u7cfb\u540e\u8f6c\u6362\u5e94\u8be5\u4e5f\u6ca1\u5565\u96be\u5ea6\u4e86\u5427 pup<\/p>\n<pre class=\"lang:javascript\">\tcanvas.onmousedown = function (e) => {\r\n\t\tvar mx = e.clientX;\r\n\t\tvar my = e.clientY;\r\n\t\tvar rect = e.target.getBoundingClientRect();\r\n\t\t\r\n\t\tpoints.push({\r\n\t\t\tx: (2 * (mx - rect.left) - canvas.height) \/ canvas.height,\r\n\t\t\ty: (canvas.width - 2 * (my - rect.top)) \/ canvas.width\r\n\t\t});\r\n\t\tdrawPoints();\r\n\t}<\/pre>\n<p class=\"indent\">\u8fd9\u6837\u6211\u4eec\u5c31\u505a\u5230\u4e86\u4e00\u4e2a\u7a0d\u590d\u6742\u4f46\u662f\u66f4\u52a0\u7075\u6d3b\u7684\u63cf\u70b9\u7f51\u9875\u4e86\uff08<\/p>\n<p><!--more--><\/p>\n<p><img loading=\"lazy\" width=\"452\" height=\"455\" src=\"https:\/\/blog.dimension.moe\/wp-content\/uploads\/webgl2.png\" alt=\"webgl2\" class=\"aligncenter size-full wp-image-415\" \/><\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4e4b\u524d\u7684\u4ee3\u7801\u5b9e\u73b0\u4e86\u63cf\u7ed8\u4e00\u4e2a\u5de8\u5927\u7684\u3001\u6b63\u65b9\u5f62\u7684\u3001\u7ea2\u8272\u7684\u70b9\uff0c\u4f46\u662f\uff0c\u7a0d\u6709\u5e38\u8bc6\u7684\u4eba\u90fd\u80fd\u770b\u51fa\uff0c\u90a3\u4e2a\u70b9\u7684\u989c\u8272\u3001\u4f4d\u7f6e\u3001\u5927\u5c0f\uff0c\u90fd\u662f &hellip; <a href=\"https:\/\/archive.ntzyz.io\/2016\/04\/10\/more-flexible-way-to-draw-a-point\/\" class=\"more-link\">\u7ee7\u7eed\u9605\u8bfb<span class=\"screen-reader-text\">[WebGL] \u66f4\u52a0\u7075\u6d3b\u7684\u63cf\u70b9\u5b9e\u73b0<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[3],"tags":[43,42,44],"_links":{"self":[{"href":"https:\/\/archive.ntzyz.io\/wp-json\/wp\/v2\/posts\/412"}],"collection":[{"href":"https:\/\/archive.ntzyz.io\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/archive.ntzyz.io\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/archive.ntzyz.io\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/archive.ntzyz.io\/wp-json\/wp\/v2\/comments?post=412"}],"version-history":[{"count":12,"href":"https:\/\/archive.ntzyz.io\/wp-json\/wp\/v2\/posts\/412\/revisions"}],"predecessor-version":[{"id":933,"href":"https:\/\/archive.ntzyz.io\/wp-json\/wp\/v2\/posts\/412\/revisions\/933"}],"wp:attachment":[{"href":"https:\/\/archive.ntzyz.io\/wp-json\/wp\/v2\/media?parent=412"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/archive.ntzyz.io\/wp-json\/wp\/v2\/categories?post=412"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/archive.ntzyz.io\/wp-json\/wp\/v2\/tags?post=412"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}