Bug 27643

Summary: Setting a glScissor that is fully offscreen does not work
Product: Mesa Reporter: Neil Roberts <nroberts>
Component: Drivers/DRI/i965Assignee: Eric Anholt <eric>
Status: RESOLVED FIXED QA Contact:
Severity: normal    
Priority: medium    
Version: git   
Hardware: Other   
OS: All   
Whiteboard:
i915 platform: i915 features:
Attachments: Test case

Description Neil Roberts 2010-04-14 10:28:19 UTC 
Created attachment 35017 [details] [review]
Test case

If I set a scissor that is zero sized and fully offscreen then I would expect it to clip everything. However on my i965 with git master nothing gets clipped. Attached is a test case for piglet to demonstrate.
Comment 1 Eric Anholt 2010-04-20 13:42:51 UTC 
commit dab3798f02259f04f3fa4e0adf6b0e31c1ebe58f
Author: Neil Roberts <neil@linux.intel.com>
Date:   Wed Apr 14 18:23:32 2010 +0100

    offscreen-scissor: New test for setting a scissor that is fully offscreen
    
    The test sets a zero-width and height scissor that is off the edge of
    the window. This should clip everything. It then tries to fill the
    window with red triangles. These do not currently get clipped on i965.
    
    Signed-off-by: Eric Anholt <eric@anholt.net>

(whoops, renamed to scissor-offscreen alongside other scissoring tests, didn't rename commit message).

commit 8e5e9cdca590109aff6840661449cdc09f70ffd8
Author: Eric Anholt <eric@anholt.net>
Date:   Tue Apr 20 13:40:28 2010 -0700

    i965: Fix scissoring when width or height is 0.
    
    We would run into trouble due to the hardware using inclusive numbers
    and the subtraction to handle that producing negative (meaning large
    positive) coordinates.
    
    Bug #27643.

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