Mesa (master): draw: clamp the viewports to always be between 0 and max

[Zack Rusin]

Module: Mesa
Branch: master
Commit: d7d676252d2ae1fd6d3dd76d4e205251ad7c6152
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=d7d676252d2ae1fd6d3dd76d4e205251ad7c6152

Author: Zack Rusin <zackr at vmware.com>
Date:   Sat May 25 01:02:46 2013 -0400

draw: clamp the viewports to always be between 0 and max

If the viewport index is larger than the PIPE_MAX_VIEWPORTS,
then the first (0-th) viewport should be used.

Signed-off-by: Zack Rusin <zackr at vmware.com>
Reviewed-by: José Fonseca<jfonseca at vmware.com>
Reviewed-by: Brian Paul <brianp at vmware.com>

---

 src/gallium/auxiliary/draw/draw_cliptest_tmp.h |    8 ++++----
 src/gallium/auxiliary/draw/draw_context.c      |    8 +++-----
 src/gallium/auxiliary/draw/draw_pipe_clip.c    |    8 ++++----
 src/gallium/auxiliary/draw/draw_private.h      |   11 +++++++++++
 src/gallium/auxiliary/draw/draw_vs_variant.c   |    5 ++---
 5 files changed, 24 insertions(+), 16 deletions(-)

diff --git a/src/gallium/auxiliary/draw/draw_cliptest_tmp.h b/src/gallium/auxiliary/draw/draw_cliptest_tmp.h
index 09e1fd7..d316b77 100644
--- a/src/gallium/auxiliary/draw/draw_cliptest_tmp.h
+++ b/src/gallium/auxiliary/draw/draw_cliptest_tmp.h
@@ -25,8 +25,6 @@
  * 
  **************************************************************************/
 
-
-
 static boolean TAG(do_cliptest)( struct pt_post_vs *pvs,
                                  struct draw_vertex_info *info )
 {
@@ -57,8 +55,10 @@ static boolean TAG(do_cliptest)( struct pt_post_vs *pvs,
          draw_current_shader_uses_viewport_index(pvs->draw) ?
          *((unsigned*)out->data[viewport_index_output]): 0;
       unsigned mask = 0x0;
-      const float *scale = pvs->draw->viewports[viewport_index].scale;
-      const float *trans = pvs->draw->viewports[viewport_index].translate;
+      const float *scale = pvs->draw->viewports[
+         draw_clamp_viewport_idx(viewport_index)].scale;
+      const float *trans = pvs->draw->viewports[
+         draw_clamp_viewport_idx(viewport_index)].translate;
   
       initialize_vertex_header(out);
 
diff --git a/src/gallium/auxiliary/draw/draw_context.c b/src/gallium/auxiliary/draw/draw_context.c
index 63ccf38..58ce270 100644
--- a/src/gallium/auxiliary/draw/draw_context.c
+++ b/src/gallium/auxiliary/draw/draw_context.c
@@ -319,14 +319,12 @@ void draw_set_viewport_states( struct draw_context *draw,
    const struct pipe_viewport_state *viewport = vps;
    draw_do_flush(draw, DRAW_FLUSH_PARAMETER_CHANGE);
 
-   if (start_slot > PIPE_MAX_VIEWPORTS)
-      return;
-
-   if ((start_slot + num_viewports) > PIPE_MAX_VIEWPORTS)
-      num_viewports = PIPE_MAX_VIEWPORTS - start_slot;
+   debug_assert(start_slot < PIPE_MAX_VIEWPORTS);
+   debug_assert((start_slot + num_viewports) <= PIPE_MAX_VIEWPORTS);
 
    memcpy(draw->viewports + start_slot, vps,
           sizeof(struct pipe_viewport_state) * num_viewports);
+
    draw->identity_viewport = (num_viewports == 1) &&
       (viewport->scale[0] == 1.0f &&
        viewport->scale[1] == 1.0f &&
diff --git a/src/gallium/auxiliary/draw/draw_pipe_clip.c b/src/gallium/auxiliary/draw/draw_pipe_clip.c
index b01e519..aacda15 100644
--- a/src/gallium/auxiliary/draw/draw_pipe_clip.c
+++ b/src/gallium/auxiliary/draw/draw_pipe_clip.c
@@ -112,8 +112,6 @@ static void copy_flat( struct draw_stage *stage,
    }
 }
 
-
-
 /* Interpolate between two vertices to produce a third.  
  */
 static void interp( const struct clip_stage *clip,
@@ -152,9 +150,11 @@ static void interp( const struct clip_stage *clip,
          *((unsigned*)in->data[viewport_index_output]) : 0;
       const float *pos = dst->pre_clip_pos;
       const float *scale =
-         clip->stage.draw->viewports[viewport_index].scale;
+         clip->stage.draw->viewports[
+            draw_clamp_viewport_idx(viewport_index)].scale;
       const float *trans =
-         clip->stage.draw->viewports[viewport_index].translate;
+         clip->stage.draw->viewports[
+            draw_clamp_viewport_idx(viewport_index)].translate;
       const float oow = 1.0f / pos[3];
 
       dst->data[pos_attr][0] = pos[0] * oow * scale[0] + trans[0];
diff --git a/src/gallium/auxiliary/draw/draw_private.h b/src/gallium/auxiliary/draw/draw_private.h
index e5f192b..f30f9af 100644
--- a/src/gallium/auxiliary/draw/draw_private.h
+++ b/src/gallium/auxiliary/draw/draw_private.h
@@ -469,4 +469,15 @@ draw_get_rasterizer_no_cull( struct draw_context *draw,
 #define DRAW_GET_IDX(_elts, _i)                   \
    (((_i) >= draw->pt.user.eltMax) ? 0 : (_elts)[_i])
 
+/**
+ * Return index of the given viewport clamping it
+ * to be between 0 <= and < PIPE_MAX_VIEWPORTS
+ */
+static INLINE unsigned
+draw_clamp_viewport_idx(int idx)
+{
+   return ((PIPE_MAX_VIEWPORTS > idx || idx < 0) ? idx : 0);
+}
+
+
 #endif /* DRAW_PRIVATE_H */
diff --git a/src/gallium/auxiliary/draw/draw_vs_variant.c b/src/gallium/auxiliary/draw/draw_vs_variant.c
index 0387eaf..152c130 100644
--- a/src/gallium/auxiliary/draw/draw_vs_variant.c
+++ b/src/gallium/auxiliary/draw/draw_vs_variant.c
@@ -91,9 +91,8 @@ find_viewport(struct draw_context *draw,
    int viewport_index =
       draw_current_shader_uses_viewport_index(draw) ?
       data[viewport_index_output * 4] : 0;
-   
-   debug_assert(viewport_index < PIPE_MAX_VIEWPORTS);
-   viewport_index = MIN2(viewport_index, PIPE_MAX_VIEWPORTS - 1);
+
+   viewport_index = draw_clamp_viewport_idx(viewport_index);
 
    return &draw->viewports[viewport_index];
 }