From: Dave Airlie <airlied@redhat.com>
Date: Wed, 13 Nov 2013 02:53:52 +0000 (+1000)
Subject: mesa/swrast: fix inverted front buffer rendering with old-school swrast
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=a43b49dfb13dc7e6d2d6d7ceee892077038d7102;p=mesa.git

mesa/swrast: fix inverted front buffer rendering with old-school swrast

I've no idea when this broke, but we have some people who wanted it fixed,
so here's my attempt.

reproducer, run readpix with swrast hit f, or run trival tri -sb things are
upside down, after this patch they aren't.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=62142
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=66213

Cc: <mesa-stable@lists.freedesktop.org>"
Signed-off-by: Dave Airlie <airlied@redhat.com>
---

diff --git a/src/mesa/drivers/dri/swrast/swrast.c b/src/mesa/drivers/dri/swrast/swrast.c
index c062071b09b..73dc5c4c061 100644
--- a/src/mesa/drivers/dri/swrast/swrast.c
+++ b/src/mesa/drivers/dri/swrast/swrast.c
@@ -406,8 +406,8 @@ swrast_map_renderbuffer(struct gl_context *ctx,
 				     (char *) xrb->Base.Buffer,
 				     dPriv->loaderPrivate);
 
-      *out_map = xrb->Base.Buffer;
-      *out_stride = stride;
+      *out_map = xrb->Base.Buffer + (h - 1) * stride;
+      *out_stride = -stride;
       return;
    }