问题描述
我正在尝试用 WebGL 和 javascript 编写一个简单的程序,以从 .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)的问题。我使用了 gl.geterror 函数,得到了 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);
gl.enabLevertexAttribArray(0);
var textureBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER,textureBuffer);
gl.bufferData(gl.ARRAY_BUFFER,texCoord,gl.STATIC_DRAW);
gl.vertexAttribPointer(1,2,0);
gl.enabLevertexAttribArray(1);
var normalBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER,normalBuffer);
gl.bufferData(gl.ARRAY_BUFFER,normArray,gl.STATIC_DRAW);
gl.vertexAttribPointer(2,0);
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,modelMatrix);
gl.clear(gl.COLOR_BUFFER_BIT);
gl.drawElements(gl.TRIANGLES,indicesArray.length,gl.UNSIGNED_SHORT,0);
requestAnimationFrame(drawFunc);
}
requestAnimationFrame(drawFunc);
这里我想画一个简单的立方体。
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(顶点 [0]=x,顶点 [1]=y,顶点 [2]=z,...)和索引数组不包含大于 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?我尝试了spector.js,但没有太大帮助,因为绘制调用由于错误而什么也不做。
解决方法
好吧,出于某种原因,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);
其余缓冲区也是如此。
,在此处查看完整示例
https://jsfiddle.net/greggman/8djzyjL3/
<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(0,1);
}
</script>
<canvas id="c"></canvas>
JS:
"use strict";
var m = ThreeDMath;
function main() {
var cubeVertices = [
-1,-1,1,];
var indices = [
0,2,3,4,5,6,7,];
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,gl.FLOAT,false,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,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,Math.cos(clock) * radius,];
var target = [0,0];
var up = [0,0];
var view = m.lookAt(eye,target,up);
var worldViewProjection = m.multiplyMatrix(view,projection);
gl.uniformMatrix4fv(worldViewProjectionLoc,worldViewProjection);
gl.drawElements(gl.LINES,indices.length,gl.UNSIGNED_SHORT,0);
requestAnimationFrame(render);
}
requestAnimationFrame(render);
}
main();