Nexus One只有一塊1GHz的CPU阿
不過3GS的3D比較強還是事實
1. 原作者的blog已經說明了N1是降成480×320在跑, 所以比較是有意義的
http://distinctivegame.wordpress.com/
so let’s change the viewport on the Nexus to the same size as the iPhone just so we can compare the two equally
2. 原作者在影片中以及blog中都有提到, 造成差異的主要原因是Android SDK尚未支援ARM的Neon浮點運算加速器
pinfantw2001 wrote:
這個問題完全沒有意義....
iphone解析約nexus one的2/5, nexus one在高解析情況下繪圖運算本就較吃力...但解析好很多.......(恕刪)
作者已經有考慮到這點了，作者的部落格 http://distinctivegame.wordpress.com/2010/02/09/dd-tech-talk-1-nexus-versus-iphone-3gs/
OK, so let’s change the viewport on the Nexus to the same size as the iPhone just so we can compare the two equally. With just two characters on screen, switching the viewport size to 480×320 on the Nexus, give a frame-rate improvement from 30fps to 40fps but with 8 characters on screen there is no difference; with the frame-rate remaining the same at 21fps.
This reveals that the bottleneck to performance must be elsewhere. The next logical test is to see if the bottleneck is CPU related. We can test this by turning off the animation bone & skinning calculations. Doing this reveals that drawing to the full screen on the Nexus with the animation disabled has no effect on the frate-rate yet when only drawing to the same screen area as the iPhone then the frame rate increases from 20fps up-to 25fps.
The conclusion is that the Nexus is primarily GPU fill-rate limited and the lack of access to the Neon float-point instructions means the CPU is only just keeping pace with the fill-rate.
Nexus即使只用 480x320 viewport，還是比較慢。2個角色時，fps 從30增加到 40，還是輸iPhone的61。但是8個角色時，fps 完全沒增加。
測試拿掉需要CPU的運算，Nexus 全螢幕時 fps 還是沒變快，但是 480x320的情況變快到25fps
結論是 Nexus 的 GPU 不夠快，CPU的運算也只剛好跟得上GPU的fill rate。
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