Starling回退到软件渲染模式的原因和解决办法

Stage3D 回退到软件渲染模式：

Software Hw_disabled=userDisabled

用户自己禁用了Flash Player的硬件加速功能。可以通过在任意网页中播放的SWF上右键点击设置>显示>勾选“硬件加速”。

HW acceleration setting checkbox in Settings UI is disabled and Stage3D is rendered using software.

Software Hw_disabled=oldDriver

显卡由于已知问题被列入黑名单，迫使Stage3D回退到软件渲染模式。需要更新显卡驱动程序解决。

HW graphics driver is blacklisted due to known issue and Stage3D is rendered using softare. It will be fixed by updating driver.

Software Hw_disabled=unavailable

显卡硬件故障或者不可能，无法使用硬件渲染，只能回退到软件渲染模式。

Unable to use hardware rendering due to driver's capability or blacklisted in general or any failure of HW graphics initialization and Stage3D is rendered using software.

Software Hw_disabled=explicit

代码中，明确设置使用软件渲染模式。

Content request a software rendering explicitly through requestContext3D and Stage3D is rendered using software