Scaled resolutions less choppy with retina?

Forkjulle

macrumors regular
Original poster
Aug 1, 2012
211
1
The retina, as everyone knows, has choppy rendering when scrolling around the screen, thanks to the machine underperforming (probably because the hardware simply can't render all the pixels as smoothly as the older Macbook Pros with fewer pixels).

My understanding is that the machine creates some sort of dividing of pixels so that the original retina display - which is almost impossible to view - becomes a copy of a 1400 display and easier to read (and very crisp).

If one chooses a scaled resolution, say 1600, isn't the dividing of pixels fewer than the retina? That is, the crispness becomes slightly less as the resolution starts moving closer to the native resolution.

Logically, wouldn't that make the choppiness less? (At native resolution, there is no choppiness.)

Or am I wrong?
 

leman

macrumors G4
Oct 14, 2008
10,289
4,811
Yes you are wrong with basically everything you say. First of all, the 'choppiness' is only observed with certain software during certain circumstances. Second, it is not hardware related but is the problem of inefficient software algorithms (well, obviously its hardware related at some level but the thing is that hardware is fast enough to do all this stuff). Third, there is no 'dividing of pixels', everything is just rendered to a 2x2 offscreen buffer and then scaled to match the native resolution. So, for retina 1440x900, the actual rendering is to a 2880x1800 buffer, for retina 1680x1050 the actual rendering is to a 3360x2100 buffer and so on.
 

goMac

macrumors 604
Apr 15, 2004
6,923
974
If one chooses a scaled resolution, say 1600, isn't the dividing of pixels fewer than the retina? That is, the crispness becomes slightly less as the resolution starts moving closer to the native resolution.

Logically, wouldn't that make the choppiness less? (At native resolution, there is no choppiness.)

Or am I wrong?
The work in theory should actually go up. The rMBP is actually converting from the lower resolution to the higher resolution every frame. So you're still outputting just as many pixels, only now with a conversion step from the lower resolution.

In addition the logical resolution is now higher, meaning the apps themselves will have to do more work too.
 

Stetrain

macrumors 68040
Feb 6, 2009
3,548
17
Logically, wouldn't that make the choppiness less? (At native resolution, there is no choppiness.)

Or am I wrong?

The way that 'retina' mode works on Mac OSX is that it makes everything double the number of pixels. A 12px font is rendered at 24px, an icon that's normally 64x64 is rendered at 128x128, etc.

In the default mode, that creates an image in which fonts, images, buttons, etc. are the same physical size as they would be on a screen at half the resolution in both directions.

Thus the 2880x1800 Macbook Pro has the same physical UI dimensions as a 1440x900 screen when in 'Best for Retina' mode.

To accomplish the other scaled modes, you leave the 'double everything' mode on (called HiDPI) and just change the desktop resolution. So to create the 'Looks Like 1920x1200' mode, the actual rendered desktop resolution is actually 3840x2400. Because everything is double sized, it has the same physical UI dimensions as a 1920x1200 screen.

So the scaled modes which give you more desktop space actually have to render more total pixels, and then downscale the new larger image to fit the native 2880x1800 resolution of the screen.