嗨，我正在关注 Edward Angel 的交互式 3D 图形简介。我想制作一个递归迷宫，但首先我需要能够制作一个基本的正方形。我根据谢尔宾斯基垫片的书籍脚本对该脚本进行了建模。我已经花了几个小时在这上面，只是看不出我做错了什么。 HTML 页面将只显示一行。我尝试过不同类型的顶点连接器，例如 LINES LINE_LOOP POLYGON，但我似乎无法让它工作。请帮助我，我感觉我快疯了。 这是脚本:
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html;charset=utf-8" >
<title>Maze Sierpinski Gasket</title>
<script id="vertex-shader" type="x-shader/x-vertex">
attribute vec4 vPosition;
void
main()
{
gl_Position = vPosition;
}
</script>
<script id="fragment-shader" type="x-shader/x-fragment">
precision mediump float;
void
main()
{
gl_FragColor = vec4( 1.0, 0.0, 0.0, 1.0 );
}
</script>
<script type="text/javascript" src="../Common/webgl-utils.js"></script>
<script type="text/javascript" src="../Common/initShaders.js"></script>
<script type="text/javascript" src="../Common/MV.js"></script>
<script>
//goal: try and draw just a square.
var canvas;
var gl;
var points = [];
window.onload = function init()
{
canvas = document.getElementById( "gl-canvas" );
gl = WebGLUtils.setupWebGL( canvas );
if ( !gl ) { alert( "WebGL isn't available" ); }
//enter new script
var vertices = [
vec2(-1.0,-1.0),
vec2(-1.0,1.0),
vec2(1.0,1.0),
vec2(1.0,-1.0)
];
square(vertices[0],vertices[1],vertices[2],vertices[3]);
//
// Configure WebGL
//
gl.viewport( 0, 0, canvas.width, canvas.height );
gl.clearColor( 1.0, 1.0, 1.0, 1.0 );
// Load shaders and initialize attribute buffers
var program = initShaders( gl, "vertex-shader", "fragment-shader" );
gl.useProgram( program );
// Load the data into the GPU
var bufferId = gl.createBuffer();
gl.bindBuffer( gl.ARRAY_BUFFER, bufferId );
gl.bufferData( gl.ARRAY_BUFFER, flatten(points), gl.STATIC_DRAW );
// Associate out shader variables with our data buffer
var vPosition = gl.getAttribLocation( program, "vPosition" );
gl.vertexAttribPointer( vPosition, 2, gl.FLOAT, false, 0, 0 );
gl.enableVertexAttribArray( vPosition );
render();
};
function square(a,b,c,d)
{
points.push(a);
points.push(b);
points.push(c);
points.push(d);
}
function render(){
gl.clear( gl.COLOR_BUFFER_BIT );
gl.drawArrays(gl.LINES, 0, points.length);
}
</script>
</head>
<body>
<canvas id="gl-canvas" width="512" height="512">
Oops ... your browser doesn't support the HTML5 canvas element
</canvas>
</body>
</html>
最佳答案
2 个问题
假设
flatten的标准实现会返回一个 JavaScript native 数组，但gl.bufferData需要一个类型化数组。所以我把它改为gl.bufferData(..., new Float32Array(flatten(...)), ...gl.LINES绘制每对点。您只传递了 4 个点，这意味着 2 条线。你不会得到一个正方形。您可以使用gl.LINE_LOOP连接所有 4 个点以及最后一个点和第一个点。
另外，当我运行你的代码时，我在 JavaScript 控制台中遇到了错误，这帮助我找到了问题。您应该始终检查 JavaScript 控制台是否有错误和警告。
//goal: try and draw just a square.
var canvas;
var gl;
var points = [];
function init()
{
canvas = document.getElementById( "gl-canvas" );
gl = WebGLUtils.setupWebGL( canvas );
if ( !gl ) { alert( "WebGL isn't available" ); }
//enter new script
var vertices = [
vec2(-1.0,-1.0),
vec2(-1.0,1.0),
vec2(1.0,1.0),
vec2(1.0,-1.0)
];
square(vertices[0],vertices[1],vertices[2],vertices[3]);
//
// Configure WebGL
//
gl.viewport( 0, 0, canvas.width, canvas.height );
gl.clearColor( 1.0, 1.0, 1.0, 1.0 );
// Load shaders and initialize attribute buffers
var program = initShaders( gl, "vertex-shader", "fragment-shader" );
gl.useProgram( program );
// Load the data into the GPU
var bufferId = gl.createBuffer();
gl.bindBuffer( gl.ARRAY_BUFFER, bufferId );
gl.bufferData( gl.ARRAY_BUFFER, new Float32Array(flatten(points)), gl.STATIC_DRAW );
// Associate out shader variables with our data buffer
var vPosition = gl.getAttribLocation( program, "vPosition" );
gl.vertexAttribPointer( vPosition, 2, gl.FLOAT, false, 0, 0 );
gl.enableVertexAttribArray( vPosition );
render();
};
function square(a,b,c,d)
{
points.push(a);
points.push(b);
points.push(c);
points.push(d);
}
function render(){
gl.clear( gl.COLOR_BUFFER_BIT );
gl.drawArrays(gl.LINE_LOOP, 0, points.length);
}
// ---------------[ missing functions ] ---------
var WebGLUtils = {
setupWebGL: function(canvas) {
return canvas.getContext("webgl");
},
};
function initShaders(gl, vs, fs) {
return twgl.createProgramFromScripts(gl, [vs, fs]);
}
function vec2(x, y) {
return [x, y];
}
function flatten(arrayOfArrays) {
var flattened = arrayOfArrays.reduce(function(a, b) {
return a.concat(b);
}, []);
return flattened;
}
init();<script id="vertex-shader" type="x-shader/x-vertex">
attribute vec4 vPosition;
void
main()
{
gl_Position = vPosition;
}
</script>
<script id="fragment-shader" type="x-shader/x-fragment">
precision mediump float;
void
main()
{
gl_FragColor = vec4( 1.0, 0.0, 0.0, 1.0 );
}
</script>
<script src="https://twgljs.org/dist/twgl.min.js"></script>
<canvas id="gl-canvas" width="512" height="512">
Oops ... your browser doesn't support the HTML5 canvas element
</canvas>关于javascript - 使用 Javascript、WebGL 和 HTML 绘制正方形，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/39298676/