[Mesa-dev] [PATCH] mesa: check for no matrix change in _mesa_LoadMatrixf()

[Brian Paul]

Some apps issue redundant glLoadMatrixf() calls with the same matrix.
Try to avoid setting dirty state in that situation.

This reduces the number of constant buffer updates by about half in
ET Quake Wars.

Tested with Piglit, ETQW, Sauerbraten, Google Earth, etc.
---
 src/mesa/main/matrix.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/mesa/main/matrix.c b/src/mesa/main/matrix.c
index b30b983..83f081e 100644
--- a/src/mesa/main/matrix.c
+++ b/src/mesa/main/matrix.c
@@ -356,9 +356,11 @@ _mesa_LoadMatrixf( const GLfloat *m )
           m[2], m[6], m[10], m[14],
           m[3], m[7], m[11], m[15]);
 
-   FLUSH_VERTICES(ctx, 0);
-   _math_matrix_loadf( ctx->CurrentStack->Top, m );
-   ctx->NewState |= ctx->CurrentStack->DirtyFlag;
+   if (memcmp(m, ctx->CurrentStack->Top->m, 16 * sizeof(GLfloat)) != 0) {
+      FLUSH_VERTICES(ctx, 0);
+      _math_matrix_loadf( ctx->CurrentStack->Top, m );
+      ctx->NewState |= ctx->CurrentStack->DirtyFlag;
+   }
 }
 
 
-- 
1.9.1