Firefox 4 and Chrome 11 dev on this machine both report DEPTH_BITS of 24. WebKit reports DEPTH_BITS of 16. Technically this satisfies the spec but delivers a subpar user experience. I haven't been able to reproduce this behavior on an early 2009 Mac Pro, a late 2010 MacBook Air, or a late 2009 MBP. I've only seen this on this iMac (notably with ATI GPU). Hardware Overview: Model Name: iMac Model Identifier: iMac11,3 ATI Radeon HD 5750: Chipset Model: ATI Radeon HD 5750 Type: GPU Bus: PCIe PCIe Lane Width: x16 VRAM (Total): 1024 MB Vendor: ATI (0x1002) Device ID: 0x68a1 Revision ID: 0x0000 ROM Revision: 113-B9710C-238 EFI Driver Version: 01.00.417 Displays: iMac: Resolution: 2560 x 1440 Pixel Depth: 32-Bit Color (ARGB8888) Main Display: Yes Mirror: Off Online: Yes Built-In: Yes Connection Type: DisplayPort
What OS are you running?
(In reply to comment #1) > What OS are you running? System Software Overview: System Version: Mac OS X 10.6.6 (10J567) Kernel Version: Darwin 10.6.0
Would you mind attaching a quick test case that shows the reported depth?
Created attachment 85566 [details] Side-by-side compare of WebKit nightly, Chrome 11 Dev, and FF4 on a late 2010 iMac
Created attachment 85567 [details] Depth buffer precision test file Also available at https://github.com/ashima/webgl-diagnostic/blob/master/depth.html