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Bug 660181 - Cogl fallbacks to software rendering instead of using GLX TFP at 30-bit color depth
Cogl fallbacks to software rendering instead of using GLX TFP at 30-bit color...
Status: RESOLVED FIXED
Product: cogl
Classification: Platform
Component: GLX
git master
Other Linux
: Normal normal
: ---
Assigned To: Cogl maintainer(s)
Cogl maintainer(s)
Depends on:
Blocks:
 
 
Reported: 2011-09-26 22:03 UTC by Damien Leone
Modified: 2011-10-01 15:46 UTC
See Also:
GNOME target: ---
GNOME version: ---

Attachments
cogl-winsys-glx: fix texture format detection (3.10 KB, patch)
2011-09-26 22:05 UTC, Damien Leone 		none Details | Review

Description Damien Leone 2011-09-26 22:03:33 UTC 
Overview:

The Texture From Pixmap extension seems to be not properly initialized when running X at 30-bit color depth (formats A2BGR10 and X2BGR10), it hence fallbacks to software rendering.

Steps to Reproduce:

1. Get hardware compatible with 30-bit color depth
2. startx -- -depth 30
3. Run any X client

Actual Results:

The following message is displayed: "Window manager warning: Log level 16: NOTE: Not using GLX TFP!"

Expected Results:

GLX TFP should be used for hardware-accelerated rendering.
Comment 1 Damien Leone 2011-09-26 22:05:51 UTC 
Created attachment 197523 [details] [review]
cogl-winsys-glx: fix texture format detection

The previous detection was based on color depth only to determine the texture format to use in GLX. If that worked fine at depths 24 (RGB8) and 32 (ARGB8), that would fail at depth 30 (BGR10) and fallback to software instead of using the TFP extension.

This commit uses an efficient population count implementation to compare the number of 1-bits in color masks against the color depth requested by the X client. If they are not equal this means that an alpha channel has been requested.
Comment 2 Robert Bragg 2011-10-01 15:46:49 UTC 
thanks a lot for the patch - I've landed this in master as 895055c83632e7c