Mesa (master): gallium: document dual source blending restrictions on gallium

[Dave Airlie]

Module: Mesa
Branch: master
Commit: 1f2b53945115f9b54933af1412d3cc0eb16a877f
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=1f2b53945115f9b54933af1412d3cc0eb16a877f

Author: Dave Airlie <airlied at redhat.com>
Date:   Fri Apr 13 17:13:01 2012 +0100

gallium: document dual source blending restrictions on gallium

As per Brian's suggestion, document the restrictions on dual src blending.

Signed-off-by: Dave Airlie <airlied at redhat.com>

---

 src/gallium/docs/source/cso/blend.rst |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)

diff --git a/src/gallium/docs/source/cso/blend.rst b/src/gallium/docs/source/cso/blend.rst
index 7bde10c..dce999c 100644
--- a/src/gallium/docs/source/cso/blend.rst
+++ b/src/gallium/docs/source/cso/blend.rst
@@ -12,7 +12,11 @@ Blend Factors
 The blend factors largely follow the same pattern as their counterparts
 in other modern and legacy drawing APIs.
 
-XXX blurb about dual-source blends
+Dual source blend factors are supported for up to 1 MRT, although
+you can advertise > 1 MRT, the stack cannot handle them for a few reasons.
+There is no definition on how the 1D array of shader outputs should be mapped
+to something that would be a 2D array (location, index). No current hardware
+exposes > 1 MRT, and we should revisit this issue if anyone ever does.
 
 Logical Operations
 ------------------