[Mesa-dev] [PATCH] i965: Fix fractional viewport coordinates handling on gen8+

[Danylo Piliaiev]

On gen8+ fractional translation of viewport moved it by a whole integer.
The behaviour in this case isn't defined anywhere but some apps like
Wine may depend on viewport's width and height being ceiled.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=106526
Signed-off-by: Danylo Piliaiev <danylo.piliaiev at gmail.com>
---
 src/mesa/drivers/dri/i965/genX_state_upload.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/genX_state_upload.c b/src/mesa/drivers/dri/i965/genX_state_upload.c
index 88fde9d..886290f 100644
--- a/src/mesa/drivers/dri/i965/genX_state_upload.c
+++ b/src/mesa/drivers/dri/i965/genX_state_upload.c
@@ -2586,12 +2586,11 @@ genX(upload_sf_clip_viewport)(struct brw_context *brw)
        * pipeline stall so we're better off just being a little more clever
        * with our viewport so we can emit it once at context creation time.
        */
-      const float viewport_Xmin = MAX2(ctx->ViewportArray[i].X, 0);
-      const float viewport_Ymin = MAX2(ctx->ViewportArray[i].Y, 0);
-      const float viewport_Xmax =
-         MIN2(ctx->ViewportArray[i].X + ctx->ViewportArray[i].Width, fb_width);
-      const float viewport_Ymax =
-         MIN2(ctx->ViewportArray[i].Y + ctx->ViewportArray[i].Height, fb_height);
+      const struct gl_viewport_attrib *vp = &ctx->ViewportArray[i];
+      const float viewport_Xmin = MAX2(vp->X, 0);
+      const float viewport_Ymin = MAX2(vp->Y, 0);
+      const float viewport_Xmax = MIN2(ceilf(vp->X + vp->Width), fb_width);
+      const float viewport_Ymax = MIN2(ceilf(vp->Y + vp->Height), fb_height);
 
       if (render_to_fbo) {
          sfv.XMinViewPort = viewport_Xmin;
-- 
2.7.4