[Mesa-dev] [PATCH] i965/Gen6-7: Do not replace texcoords with point coord if not drawing points

[Chris Forbes]

Fixes broken rendering in Windows-based QtQuick2 apps run through Wine.
This library sets all texture units' GL_COORD_REPLACE, leaves point
sprite mode enabled, and then draws a triangle fan.

Will need a slightly different fix for Gen4-5, but I don't have my old
machines in a usable state currently.

V2: - Simplify patch -- the real changes are no longer duplicated across
      the Gen6 and Gen7 atoms.
    - Also don't clobber attr overrides -- which matters on Haswell too,
      and fixes the other half of the problem
    - Fix newly-introduced warnings

Signed-off-by: Chris Forbes <chrisf at ijw.co.nz>
Cc: "10.4" <mesa-stable at lists.freedesktop.org>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=84651
---
 src/mesa/drivers/dri/i965/gen6_sf_state.c | 54 ++++++++++++++++++++++++-------
 src/mesa/drivers/dri/i965/gen7_sf_state.c |  3 +-
 2 files changed, 45 insertions(+), 12 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/gen6_sf_state.c b/src/mesa/drivers/dri/i965/gen6_sf_state.c
index 24d2754..778c6d3 100644
--- a/src/mesa/drivers/dri/i965/gen6_sf_state.c
+++ b/src/mesa/drivers/dri/i965/gen6_sf_state.c
@@ -129,6 +129,18 @@ get_attr_override(const struct brw_vue_map *vue_map, int urb_entry_read_offset,
 }
 
 
+static bool
+is_drawing_points(const struct brw_context *brw)
+{
+   /* Determine if the primitives *reaching the SF* are points */
+   const struct gl_context *ctx = &brw->ctx;
+   if (ctx->GeometryProgram._Current)
+      return ctx->GeometryProgram._Current->OutputType == GL_POINTS;
+   else
+      return brw->primitive == _3DPRIM_POINTLIST;
+}
+
+
 /**
  * Create the mapping from the FS inputs we produce to the previous pipeline
  * stage (GS or VS) outputs they source from.
@@ -149,6 +161,23 @@ calculate_attr_overrides(const struct brw_context *brw,
    /* _NEW_LIGHT */
    bool shade_model_flat = brw->ctx.Light.ShadeModel == GL_FLAT;
 
+   /* From the Ivybridge PRM, Vol 2 Part 1, 3DSTATE_SBE,
+    * description of dw10 Point Sprite Texture Coordinate Enable:
+    *
+    * "This field must be programmed to zero when non-point primitives
+    * are rendered."
+    *
+    * The SandyBridge PRM doesn't explicitly say that point sprite enables
+    * must be programmed to zero when rendering non-point primitives, but
+    * the IvyBridge PRM does, and if we don't, we get garbage.
+    *
+    * This is not required on Haswell, as the hardware ignores this state
+    * when drawing non-points -- although we do still need to be careful to
+    * correctly set the attr overrides.
+    */
+   /* BRW_NEW_PRIMITIVE | _NEW_PROGRAM */
+   bool drawing_points = is_drawing_points(brw);
+
    /* Initialize all the attr_overrides to 0.  In the loop below we'll modify
     * just the ones that correspond to inputs used by the fs.
     */
@@ -167,18 +196,20 @@ calculate_attr_overrides(const struct brw_context *brw,
 
       /* _NEW_POINT */
       bool point_sprite = false;
-      if (brw->ctx.Point.PointSprite &&
-	  (attr >= VARYING_SLOT_TEX0 && attr <= VARYING_SLOT_TEX7) &&
-	  brw->ctx.Point.CoordReplace[attr - VARYING_SLOT_TEX0]) {
-         point_sprite = true;
+      if (drawing_points) {
+         if (brw->ctx.Point.PointSprite &&
+             (attr >= VARYING_SLOT_TEX0 && attr <= VARYING_SLOT_TEX7) &&
+             brw->ctx.Point.CoordReplace[attr - VARYING_SLOT_TEX0]) {
+            point_sprite = true;
+         }
+
+         if (attr == VARYING_SLOT_PNTC)
+            point_sprite = true;
+
+         if (point_sprite)
+            *point_sprite_enables |= (1 << input_index);
       }
 
-      if (attr == VARYING_SLOT_PNTC)
-         point_sprite = true;
-
-      if (point_sprite)
-	 *point_sprite_enables |= (1 << input_index);
-
       /* flat shading */
       if (interp_qualifier == INTERP_QUALIFIER_FLAT ||
           (shade_model_flat && is_gl_Color &&
@@ -411,7 +442,8 @@ const struct brw_tracked_state gen6_sf_state = {
                 _NEW_MULTISAMPLE),
       .brw   = (BRW_NEW_CONTEXT |
 		BRW_NEW_FRAGMENT_PROGRAM |
-                BRW_NEW_VUE_MAP_GEOM_OUT),
+                BRW_NEW_VUE_MAP_GEOM_OUT |
+                BRW_NEW_PRIMITIVE),
       .cache = CACHE_NEW_WM_PROG
    },
    .emit = upload_sf_state,
diff --git a/src/mesa/drivers/dri/i965/gen7_sf_state.c b/src/mesa/drivers/dri/i965/gen7_sf_state.c
index 109b825..371b9de 100644
--- a/src/mesa/drivers/dri/i965/gen7_sf_state.c
+++ b/src/mesa/drivers/dri/i965/gen7_sf_state.c
@@ -93,7 +93,8 @@ const struct brw_tracked_state gen7_sbe_state = {
 		_NEW_PROGRAM),
       .brw   = (BRW_NEW_CONTEXT |
 		BRW_NEW_FRAGMENT_PROGRAM |
-                BRW_NEW_VUE_MAP_GEOM_OUT),
+                BRW_NEW_VUE_MAP_GEOM_OUT |
+                BRW_NEW_PRIMITIVE),
       .cache = CACHE_NEW_WM_PROG
    },
    .emit = upload_sbe_state,
-- 
2.1.3