st/nine: Don't call u_box_union_* when dirty region is empty

When dirty region is empty, u_box_union_* incorrectly expands
the new region.

This fixes broken font rendering issue in WOLF RPG Editor v2.10 games.

Signed-off-by: Masanori Kakura <[email protected]>
Reviewed-by: Axel Davy <[email protected]>

1 files changed, 7 insertions, 3 deletions

diff --git a/src/gallium/state_trackers/nine/volumetexture9.c b/src/gallium/state_trackers/nine/volumetexture9.c
index 5c83fdb60ce..c836dd21023 100644
--- a/src/gallium/state_trackers/nine/volumetexture9.c
+++ b/src/gallium/state_trackers/nine/volumetexture9.c
@@ -222,9 +222,13 @@ NineVolumeTexture9_AddDirtyBox( struct NineVolumeTexture9 *This,
         This->dirty_box.height = This->base.base.info.height0;
         This->dirty_box.depth = This->base.base.info.depth0;
     } else {
-        struct pipe_box box;
-        d3dbox_to_pipe_box(&box, pDirtyBox);
-        u_box_union_3d(&This->dirty_box, &This->dirty_box, &box);
+        if (This->dirty_box.width == 0) {
+            d3dbox_to_pipe_box(&This->dirty_box, pDirtyBox);
+        } else {
+            struct pipe_box box;
+            d3dbox_to_pipe_box(&box, pDirtyBox);
+            u_box_union_3d(&This->dirty_box, &This->dirty_box, &box);
+        }
         This->dirty_box.x = MAX2(This->dirty_box.x, 0);
         This->dirty_box.y = MAX2(This->dirty_box.y, 0);
         This->dirty_box.z = MAX2(This->dirty_box.z, 0);