From 8cd59857a99c534c560f58c931f5c2466d4c1f9b Mon Sep 17 00:00:00 2001
From: marha <marha@users.sourceforge.net>
Date: Sun, 23 Jan 2011 16:30:09 +0000
Subject: mesalib git update 23/1/2011

---
 mesalib/src/mesa/state_tracker/st_atom_viewport.c | 4 ++++
 1 file changed, 4 insertions(+)

(limited to 'mesalib/src/mesa/state_tracker/st_atom_viewport.c')

diff --git a/mesalib/src/mesa/state_tracker/st_atom_viewport.c b/mesalib/src/mesa/state_tracker/st_atom_viewport.c
index 0cde4d0ec..df26fb4a6 100644
--- a/mesalib/src/mesa/state_tracker/st_atom_viewport.c
+++ b/mesalib/src/mesa/state_tracker/st_atom_viewport.c
@@ -47,10 +47,14 @@ update_viewport( struct st_context *st )
    /* _NEW_BUFFERS
     */
    if (st_fb_orientation(ctx->DrawBuffer) == Y_0_TOP) {
+      /* Drawing to a window.  The corresponding gallium surface uses
+       * Y=0=TOP but OpenGL is Y=0=BOTTOM.  So we need to invert the viewport.
+       */
       yScale = -1;
       yBias = (GLfloat)ctx->DrawBuffer->Height;
    }
    else {
+      /* Drawing to an FBO where Y=0=BOTTOM, like OpenGL - don't invert */
       yScale = 1.0;
       yBias = 0.0;
    }
-- 
cgit v1.2.3