1 files changed, 43 insertions, 2 deletions
diff --git a/src/mesa/main/api_validate.c b/src/mesa/main/api_validate.c
index 17da5d01b7e..02495a15a90 100644
--- a/src/mesa/main/api_validate.c
+++ b/src/mesa/main/api_validate.c
@@ -29,6 +29,7 @@
 #include "imports.h"
 #include "mfeatures.h"
 #include "mtypes.h"
+#include "enums.h"
 #include "vbo/vbo.h"
 
 
@@ -215,9 +216,49 @@ _mesa_valid_prim_mode(struct gl_context *ctx, GLenum mode, const char *name)
       _mesa_error(ctx, GL_INVALID_ENUM, "%s(mode=%x)", name, mode);
       return GL_FALSE;
    }
-   else {
-      return GL_TRUE;
+
+   /* From the GL_EXT_transform_feedback spec:
+    *
+    *     "The error INVALID_OPERATION is generated if Begin, or any command
+    *      that performs an explicit Begin, is called when:
+    *
+    *      * a geometry shader is not active and <mode> does not match the
+    *        allowed begin modes for the current transform feedback state as
+    *        given by table X.1.
+    *
+    *      * a geometry shader is active and the output primitive type of the
+    *        geometry shader does not match the allowed begin modes for the
+    *        current transform feedback state as given by table X.1.
+    *
+    */
+   if (ctx->TransformFeedback.CurrentObject->Active &&
+       !ctx->TransformFeedback.CurrentObject->Paused) {
+      GLboolean pass = GL_TRUE;
+
+      switch (mode) {
+      case GL_POINTS:
+         pass = ctx->TransformFeedback.Mode == GL_POINTS;
+	 break;
+      case GL_LINES:
+      case GL_LINE_STRIP:
+      case GL_LINE_LOOP:
+         pass = ctx->TransformFeedback.Mode == GL_LINES;
+	 break;
+      default:
+         pass = ctx->TransformFeedback.Mode == GL_TRIANGLES;
+	 break;
+      }
+      if (!pass) {
+	 _mesa_error(ctx, GL_INVALID_OPERATION,
+		     "%s(mode=%s vs transform feedback %s)",
+		     name,
+		     _mesa_lookup_prim_by_nr(mode),
+		     _mesa_lookup_prim_by_nr(ctx->TransformFeedback.Mode));
+	 return GL_FALSE;
+      }
    }
+
+   return GL_TRUE;
 }