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我正在尝试用 WebGL 和 javascript 编写一个简单的程序来从 .obj 文件中绘制一个简单的对象。我正在使用 npm 的 webgl-obj-loader 来加载对象。正如标题所说，我不断收到缓冲区大小不足（边缘）和索引缓冲区太小（FF）。我使用了 gl.geterror 函数，我得到 1282 错误代码，这意味着 INVALID_OPERATION。

window.onload = function () {
            OBJ.downloadMeshes(
            {
                'dragon_vrip': 'models/dragon_vrip.obj',
                'cube2': 'models/cube2.obj'
            }, webGLStart);
}

这是我用来加载 obj 文件的方式。

        app.meshes = meshes;

        OBJ.initMeshBuffers(gl, app.meshes.dragon_vrip);
        OBJ.initMeshBuffers(gl, app.meshes.cube2);

        vertArray = app.meshes.cube2.vertices.slice();
        normArray = app.meshes.cube2.vertexNormals.slice();
        indicesArray = app.meshes.cube2.indices.slice();
        texCoord = app.meshes.cube2.textures.slice();

            var myMesh=app.meshes.cube2;

            var pointsBuffer = gl.createBuffer();
            gl.bindBuffer(gl.ARRAY_BUFFER, pointsBuffer);
            gl.bufferData(gl.ARRAY_BUFFER, vertArray, gl.STATIC_DRAW);
            gl.vertexAttribPointer(0, 3, gl.FLOAT, false, 0, 0);
            gl.enableVertexAttribArray(0);

            var textureBuffer = gl.createBuffer();
            gl.bindBuffer(gl.ARRAY_BUFFER, textureBuffer);
            gl.bufferData(gl.ARRAY_BUFFER, texCoord, gl.STATIC_DRAW);
            gl.vertexAttribPointer(1, 2, gl.FLOAT, false, 0, 0);
            gl.enableVertexAttribArray(1);

            var normalBuffer = gl.createBuffer();
            gl.bindBuffer(gl.ARRAY_BUFFER, normalBuffer);
            gl.bufferData(gl.ARRAY_BUFFER, normArray, gl.STATIC_DRAW);
            gl.vertexAttribPointer(2, 3, gl.FLOAT, false, 0, 0);
            gl.enableVertexAttribArray(2);

            var indices = gl.createBuffer();
            gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, indices);
            gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, indicesArray, gl.STATIC_DRAW);
            console.log(indices.size);

第二步：初始化缓冲区。

                function drawFunc() {
                    rotateAngleX += 0.01;
                    rotateAngleY += 0.02;

                    mat4.fromXRotation(rotateXMatrix, rotateAngleX);
                    mat4.fromYRotation(rotateYMatrix, rotateAngleY);
                    mat4.multiply(modelMatrix, rotateXMatrix, rotateYMatrix);

                    gl.uniformMatrix4fv(modelMatrixLocation, false, modelMatrix);

                    gl.clear(gl.COLOR_BUFFER_BIT);
                    gl.drawElements(gl.TRIANGLES, indicesArray.length, gl.UNSIGNED_SHORT, 0);

                    requestAnimationFrame(drawFunc);

                }
                requestAnimationFrame(drawFunc);

在这里，我正在尝试绘制一个简单的立方体。

数组大小为：顶点：72 索引：36 texCoords：48 法线：72

考虑到顶点是 x,y,z 点的三元组，顶点缓冲区包含 24 个点（vertex[0]=x, vertex[1]=y, vertex[2]=z, ...），并且索引数组没有包含高于 23 的数字，所以我不明白错误发生在哪里。还有什么方法可以调试缓冲区吗？我尝试了 spector.js，但没有太大帮助，因为绘图调用由于错误而无济于事。

4

2 回答 2

2

好的，由于某种原因，我不得不在 bufferdata 函数中添加新类型的数组，就像这样。

var indices = gl.createBuffer();
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, indices);
gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new Uint32Array(indicesArray),gl.STATIC_DRAW);

其余的缓冲区也是如此。

于 2021-04-13T13:30:01.773 回答
1

请参阅下面的完整示例：

"use strict";

var m = ThreeDMath;

function main() {
  var cubeVertices = [-1, -1, -1,
    1, -1, -1,
    1, 1, -1, -1, 1, -1, -1, -1, 1,
    1, -1, 1,
    1, 1, 1, -1, 1, 1,
  ];
  var indices = [
    0, 1,
    1, 2,
    2, 3,
    3, 0,
    4, 5,
    5, 6,
    6, 7,
    7, 4,
    0, 4,
    1, 5,
    2, 6,
    3, 7,
  ];

  var canvas = document.getElementById("c");
  var gl = canvas.getContext("webgl");
  if (!gl) {
    alert("no webgl");
    return;
  }

  var program = webglUtils.createProgramFromScripts(
    gl, ["2d-vertex-shader", "2d-fragment-shader"]);
  gl.useProgram(program);

  var positionLoc = gl.getAttribLocation(program, "a_position");
  var worldViewProjectionLoc =
    gl.getUniformLocation(program, "u_worldViewProjection");

  var buffer = gl.createBuffer();
  gl.bindBuffer(gl.ARRAY_BUFFER, buffer);
  gl.bufferData(
    gl.ARRAY_BUFFER,
    new Float32Array(cubeVertices),
    gl.STATIC_DRAW);
  gl.enableVertexAttribArray(positionLoc);
  gl.vertexAttribPointer(positionLoc, 3, gl.FLOAT, false, 0, 0);

  var buffer = gl.createBuffer();
  gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, buffer);
  gl.bufferData(
    gl.ELEMENT_ARRAY_BUFFER,
    new Uint16Array(indices),
    gl.STATIC_DRAW);

  function render(clock) {
    clock *= 0.001;

    var scale = 4;

    webglUtils.resizeCanvasToDisplaySize(gl.canvas, window.devicePixelRatio);

    gl.viewport(0, 0, gl.canvas.width, gl.canvas.height);

    gl.clear(gl.COLOR_BUFFER_BIT);

    var fieldOfView = Math.PI * 0.25;
    var aspect = canvas.clientWidth / canvas.clientHeight;
    var projection = m.perspective(fieldOfView, aspect, 0.0001, 500);
    var radius = 5;
    var eye = [
      Math.sin(clock) * radius,
      1,
      Math.cos(clock) * radius,
    ];
    var target = [0, 0, 0];
    var up = [0, 1, 0];
    var view = m.lookAt(eye, target, up);

    var worldViewProjection = m.multiplyMatrix(view, projection);
    gl.uniformMatrix4fv(worldViewProjectionLoc, false, worldViewProjection);

    gl.drawElements(gl.LINES, indices.length, gl.UNSIGNED_SHORT, 0);
    requestAnimationFrame(render);
  }
  requestAnimationFrame(render);
}

main();
<script src="https://webglfundamentals.org/webgl/resources/webgl-utils.js"></script>
<script src="https://webglfundamentals.org/webgl/resources/webgl-lessons-helper.js"></script>
<script src="https://webglfundamentals.org/webgl/lessons/resources/3d-math.js"></script>
<!-- vertex shader -->
<script id="2d-vertex-shader" type="x-shader/x-vertex">
  attribute vec4 a_position; uniform mat4 u_worldViewProjection; void main() { gl_Position = u_worldViewProjection * a_position; }
</script>
<!-- fragment shader -->
<script id="2d-fragment-shader" type="x-shader/x-fragment">
  void main() { gl_FragColor = vec4(0,0,0,1); }
</script>
<canvas id="c"></canvas>

JSFiddle 上的工作代码

于 2021-04-13T14:44:13.010 回答