Mesa (master): svga: fix zero-stride vertex array bug

[Brian Paul]

Module: Mesa
Branch: master
Commit: fc71e0b4a8623dc1e0657a19998f54d5a5c491e1
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=fc71e0b4a8623dc1e0657a19998f54d5a5c491e1

Author: Brian Paul <brianp at vmware.com>
Date:   Thu May 17 10:07:46 2012 -0600

svga: fix zero-stride vertex array bug

For zero-stride vertex arrays, the svga driver copies the value into
the constant value and uses that value in the shader.  The recent
gallium-userbuf changes caused a regression in this.  An example
symptom was per-primitive glColor3f() calls getting ignored.

Where we copied the vertex value from the vertex buffer to the
constant buffer we neglected to take into account the
pipe_vertex_buffer::buffer_offset field.  Adding that value to the
source offset fixes the problem.  Actually, it looks like we should
have been doing this all along, but it never was an issue before for
some reason.

---

 src/gallium/drivers/svga/svga_state_vs.c |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/gallium/drivers/svga/svga_state_vs.c b/src/gallium/drivers/svga/svga_state_vs.c
index 3cb0cdb..1d140bd 100644
--- a/src/gallium/drivers/svga/svga_state_vs.c
+++ b/src/gallium/drivers/svga/svga_state_vs.c
@@ -222,7 +222,11 @@ struct svga_tracked_state svga_hw_vs =
 };
 
 
-/***********************************************************************
+/**
+ * This function handles the special case of vertex attributes
+ * with stride=0.  Basically, copy those values into the constant
+ * buffer and modify the vertex shader to get the values from the
+ * constant buffer rather than a vertex array.
  */
 static enum pipe_error
 update_zero_stride( struct svga_context *svga,
@@ -269,7 +273,7 @@ update_zero_stride( struct svga_context *svga,
          
          mapped_buffer = pipe_buffer_map_range(&svga->pipe, 
                                                vbuffer->buffer,
-                                               vel->src_offset,
+                                               vel->src_offset + vbuffer->buffer_offset,
                                                util_format_get_blocksize(vel->src_format),
                                                PIPE_TRANSFER_READ,
 					       &transfer);