Bug 94128 - Other multisample "broadcast" blits do not work
Summary: Other multisample "broadcast" blits do not work
Status: NEW
Alias: None
Product: Mesa
Classification: Unclassified
Component: Drivers/DRI/i965 (show other bugs)
Version: git
Hardware: Other All
: medium normal
Assignee: Intel 3D Bugs Mailing List
QA Contact: Intel 3D Bugs Mailing List
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Reported: 2016-02-13 01:17 UTC by Ian Romanick
Modified: 2016-11-03 21:11 UTC (History)
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Description Ian Romanick 2016-02-13 01:17:07 UTC
The glBlitFramebuffer man page says:

    When the color buffer is transferred, values are taken from the read
    buffer of the read framebuffer and written to each of the draw buffers
    of the draw framebuffer.

Commit a6022e54 modified one path through meta to use gl_FragColor to implement this behavior for multisample-to-singlesample "broadcast" blits where the destination has multiple enabled color buffers.  This fixed the GLES3 confromance test framebuffer_blit_functionality_multisampled_to_singlesampled_blit.

Based on inspection of the code (and the commit message for a6022e54), broadcast blits involving integer (or unsigned integer) color buffers or multisample-to-multisample blits are still broken.  I am currently working on patches that will happen to fix the integer cases.

However, we need test cases.  There is one related test case on the GLES3 CTS, and there are zero related test cases in piglit.  We need to verify the full cross product of (MS-to-MS, MS-to-SS) x (normalized, integer, unsigned integer, depth component).
Comment 1 Ian Romanick 2016-02-13 01:22:13 UTC
It's actually a 3-dimensional matrix: (MS-to-MS, MS-to-SS) × (normalized, integer, unsigned integer, depth component) × (1:1, scaled).
Comment 2 Ian Romanick 2016-02-13 01:27:27 UTC
Remove depth component.  There can only be one depth buffer.  It's only color buffers that can be broadcast.  Duh.


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