此代码

gl.vertexAttribPointer(this.program.vertexPosAttrib, this.itemSize, gl.FLOAT, false, 0, 0);
gl.enableVertexAttribArray(this.program.vertexPosAttrib);

绘制每个网格时需要调用，而不是现在调用它。此外，在为 this.program.vertexPosAttrib 调用 gl.vertexAttribPointer 之前，您需要致电

Need to be called when drawing each mesh and not where it's called now. Additionally before calling gl.vertexAttribPointer for this.program.vertexPosAttrib you need to call

gl.bindBuffer(gl.ARRAY_BUFFER, mesh.buffers.vertexPosition);

因为 gl.vertexAttribPointer 当前绑定缓冲区绑定到 gl.ARRAY_BUFFER 到指定的属性。

Because gl.vertexAttribPointer binds the buffer currently bound to gl.ARRAY_BUFFER to the specified attribute.

换句话说

gl.bindBuffer(gl.ARRAY_BUFFER, mesh.buffers.vertexPosition);
gl.vertexAttribPointer(mesh.program.vertexPosAttrib, mesh.itemSize, gl.FLOAT, false, 0, 0);
gl.enableVertexAttribArray(mesh.program.vertexPosAttrib);