I have a question about the retina screen.
For example, I draw a rectangle on screen by OpenGL with shading , the size is the same as iPhone screen.
For iPhone without retina screen, the size is 320*480. From my understanding, there would be 320*480 times fragment shader computing. For iphone with retina, is the computing becomes 320*480*4? Or still 320*480.
Best Regards,
Depends. If you just render into a 320×480 framebuffer, you just render into a 320×480 framebuffer and let the device do some simple upscaling. However, if you render into a 640×960 framebuffer, render into a 640×960 framebuffer. Rendering into a higher resolution always comes at its costs, you can see this on the PC quite good were your computer might be able to handle 1024×768 pixels at full settings but only medium settings on 1920×1200. Luckily, the latter doesn’t apply to iOS since the Hardware scaled with the display, in fact, you are even able to render much higher quality scenes on an iPhone 4 with retina display support than you are able to do on an iPhone 3GS.
For “the new iPad”… who knows, but if the GPU is really two times faster than the one in the iPad 2, its gonna be able to really draw astonishing scenes in full resolution.