WebGL读取模板缓冲区

Question

您好我花了很多时间试图在WebGL中进行简单的选择。我在绘制每个对象之前使用过：

if(Window.stencilEnabled)
                    gl.stencilFunc(gl.ALWAYS, mesh.pickingID, -1);

最后：

        mouse_x = this.lastPickingCoords.x;
        mouse_y = this.lastPickingCoords.y;

        var pixels = new Uint8Array(4);
        if (gl.checkFramebufferStatus(gl.FRAMEBUFFER) == gl.FRAMEBUFFER_COMPLETE) {
            gl.readPixels(mouse_x, mouse_y, 1, 1, gl.STENCIL_INDEX, gl.UNSIGNED_BYTE, pixels);
        }else{
            console.log("Framebuffer error.");
        }
        oID = -1 + pixels[0];
        console.log("Picking object: " + oID + " at " + mouse_x + ":" + mouse_y);       

        if(this.mapArray[oID] != undefined){
            console.log("Object exists!");
            console.log(this.mapArray[oID]);
        }else{
            console.log("Object not found");
        }

        this.lastPickingCoords.x = 0;   
        this.lastPickingCoords.y = 0;

但似乎是错误＆＃34; WebGL：INVALID_ENUM：readPixels：格式无效＆＃34;不允许读取模板缓冲区...是否有任何解决方法，扩展名？如何在不编写选择着色器的情况下以其他方式执行操作谢谢。