[Mesa-dev] [PATCH 1/4] vbo: Remove pedantic warning about 'end' beind out of bounds.

[Kenneth Graunke]

The application supplied [start, end] range is merely a conservative
hint of the ranges of index values inside the index buffer.  There is no
requirement that all vertices in the range [start, end] be referenced.

Passing an 'end' value larger than the maximum legal index is perfectly
acceptible; applications can legally pass 0xffffffff when they don't
have a tighter bound readily available.

Thus, the warning doesn't indicate a correctness issue; it could only
indicate a performance issue.  However, it does not even do that.

glDrawRangeElements is designed to optimize non-VBO vertex data uploads
by providing an upper bound on the size of buffers a driver would need
to allocate.  With VBOs, the data is already in an uploaded buffer, so
the range doesn't help.

The clincher is: we only know _MaxElement for VBOs.  For user-space
arrays, we just set it to 2,000,000,000 (see mesa/main/varray.h:63.)
So we can only check this in the case where it is not useful.

Many applications, including the Unigine demos, currently trigger this
warning, which suggests the applications are buggy when they're actually
fine.  Eliminating the warning should confuse users less while not
actually losing any benefit to application developers.

NOTE: This is a candidate for release branches.

Suggested-by: Jose Fonseca <jfonseca at vmware.com>
Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
Reviewed-by: Brian Paul <brianp at vmware.com>
---
 src/mesa/vbo/vbo_exec_array.c |   49 +---------------------------------------
 1 files changed, 2 insertions(+), 47 deletions(-)

diff --git a/src/mesa/vbo/vbo_exec_array.c b/src/mesa/vbo/vbo_exec_array.c
index d6b4d61..ec4cb4f 100644
--- a/src/mesa/vbo/vbo_exec_array.c
+++ b/src/mesa/vbo/vbo_exec_array.c
@@ -708,6 +708,7 @@ vbo_exec_DrawArraysInstanced(GLenum mode, GLint start, GLsizei count,
  * Map GL_ELEMENT_ARRAY_BUFFER and print contents.
  * For debugging.
  */
+#if 0
 static void
 dump_element_buffer(struct gl_context *ctx, GLenum type)
 {
@@ -759,6 +760,7 @@ dump_element_buffer(struct gl_context *ctx, GLenum type)
 
    ctx->Driver.UnmapBuffer(ctx, ctx->Array.ArrayObj->ElementArrayBufferObj);
 }
+#endif
 
 
 /**
@@ -856,7 +858,6 @@ vbo_exec_DrawRangeElementsBaseVertex(GLenum mode,
 				     const GLvoid *indices,
 				     GLint basevertex)
 {
-   static GLuint warnCount = 0;
    GET_CURRENT_CONTEXT(ctx);
 
    if (MESA_VERBOSE & VERBOSE_DRAW)
@@ -886,52 +887,6 @@ vbo_exec_DrawRangeElementsBaseVertex(GLenum mode,
    }
 
    if (end >= ctx->Array.ArrayObj->_MaxElement) {
-      /* the max element is out of bounds of one or more enabled arrays */
-      warnCount++;
-
-      if (warnCount < 10) {
-         _mesa_warning(ctx, "glDraw[Range]Elements(start %u, end %u, count %d, "
-                       "type 0x%x, indices=%p)\n"
-                       "\tend is out of bounds (max=%u)  "
-                       "Element Buffer %u (size %d)\n"
-                       "\tThis should probably be fixed in the application.",
-                       start, end, count, type, indices,
-                       ctx->Array.ArrayObj->_MaxElement - 1,
-                       ctx->Array.ArrayObj->ElementArrayBufferObj->Name,
-                       (int) ctx->Array.ArrayObj->ElementArrayBufferObj->Size);
-      }
-
-      if (0)
-         dump_element_buffer(ctx, type);
-
-      if (0)
-         _mesa_print_arrays(ctx);
-
-      /* 'end' was out of bounds, but now let's check the actual array
-       * indexes to see if any of them are out of bounds.
-       */
-      if (0) {
-         GLuint max = _mesa_max_buffer_index(ctx, count, type, indices,
-                                             ctx->Array.ArrayObj->ElementArrayBufferObj);
-         if (max >= ctx->Array.ArrayObj->_MaxElement) {
-            if (warnCount < 10) {
-               _mesa_warning(ctx, "glDraw[Range]Elements(start %u, end %u, "
-                             "count %d, type 0x%x, indices=%p)\n"
-                             "\tindex=%u is out of bounds (max=%u)  "
-                             "Element Buffer %u (size %d)\n"
-                             "\tSkipping the glDrawRangeElements() call",
-                             start, end, count, type, indices, max,
-                             ctx->Array.ArrayObj->_MaxElement - 1,
-                             ctx->Array.ArrayObj->ElementArrayBufferObj->Name,
-                             (int) ctx->Array.ArrayObj->ElementArrayBufferObj->Size);
-            }
-         }
-         /* XXX we could also find the min index and compare to 'start'
-          * to see if start is correct.  But it's more likely to get the
-          * upper bound wrong.
-          */
-      }
-
       /* Set 'end' to the max possible legal value */
       assert(ctx->Array.ArrayObj->_MaxElement >= 1);
       end = ctx->Array.ArrayObj->_MaxElement - 1;
-- 
1.7.7.6