Merge branch '7.8' into master

[mesa.git] / src / mesa / state_tracker / st_atom_scissor.c

diff --git a/src/mesa/state_tracker/st_atom_scissor.c b/src/mesa/state_tracker/st_atom_scissor.c
index 3fd59e1945c2677b2de1cf8bbc3fd3388c7f50a8..5e0c51cff0af3f273a2c922899cf005cd64813eb 100644 (file)
--- a/src/mesa/state_tracker/st_atom_scissor.c
+++ b/src/mesa/state_tracker/st_atom_scissor.c
@@ -31,6 +31,7 @@
   */
  
 
+#include "main/macros.h"
 #include "st_context.h"
 #include "pipe/p_context.h"
 #include "st_atom.h"
@@ -52,15 +53,19 @@ update_scissor( struct st_context *st )
    scissor.maxy = fb->Height;
 
    if (st->ctx->Scissor.Enabled) {
-      if ((GLuint)st->ctx->Scissor.X > scissor.minx)
+      /* need to be careful here with xmax or ymax < 0 */
+      GLint xmax = MAX2(0, st->ctx->Scissor.X + st->ctx->Scissor.Width);
+      GLint ymax = MAX2(0, st->ctx->Scissor.Y + st->ctx->Scissor.Height);
+
+      if (st->ctx->Scissor.X > (GLint)scissor.minx)
          scissor.minx = st->ctx->Scissor.X;
-      if ((GLuint)st->ctx->Scissor.Y > scissor.miny)
+      if (st->ctx->Scissor.Y > (GLint)scissor.miny)
          scissor.miny = st->ctx->Scissor.Y;
 
-      if ((GLuint)st->ctx->Scissor.X + st->ctx->Scissor.Width < scissor.maxx)
-         scissor.maxx = st->ctx->Scissor.X + st->ctx->Scissor.Width;
-      if ((GLuint)st->ctx->Scissor.Y + st->ctx->Scissor.Height < scissor.maxy)
-         scissor.maxy = st->ctx->Scissor.Y + st->ctx->Scissor.Height;
+      if (xmax < (GLint) scissor.maxx)
+         scissor.maxx = xmax;
+      if (ymax < (GLint) scissor.maxy)
+         scissor.maxy = ymax;
 
       /* check for null space */
       if (scissor.minx >= scissor.maxx || scissor.miny >= scissor.maxy)