mesa: Record transform feedback strides/offsets in linker output.

This patch adds two new fields to the gl_transform_feedback_info
struct:

- BufferStride records the total number of components (per vertex)
  that transform feedback is being instructed to store in each buffer.

- Outputs[i].DstOffset records the offset within the interleaved
  structure of each transform feedback output.

These values are needed by the i965 gen6 and r600g back-ends, so it
seems better to have the linker provide them rather than force each
back-end to compute them independently.

Also, DstOffset helps pave the way for supporting
ARB_transform_feedback3, which allows the transform feedback output to
contain holes between attributes by specifying
gl_SkipComponents{1,2,3,4} as the varying name.

Reviewed-by: Marek Olšák <[email protected]>

1 files changed, 10 insertions, 0 deletions

diff --git a/src/mesa/main/mtypes.h b/src/mesa/main/mtypes.h
index 0e29dc0dc79..93bf04ec097 100644
--- a/src/mesa/main/mtypes.h
+++ b/src/mesa/main/mtypes.h
@@ -1821,7 +1821,17 @@ struct gl_transform_feedback_info {
       unsigned OutputRegister;
       unsigned OutputBuffer;
       unsigned NumComponents;
+
+      /** offset (in DWORDs) of this output within the interleaved structure */
+      unsigned DstOffset;
    } Outputs[MAX_PROGRAM_OUTPUTS];
+
+   /**
+    * Total number of components stored in each buffer.  This may be used by
+    * hardware back-ends to determine the correct stride when interleaving
+    * multiple transform feedback outputs in the same buffer.
+    */
+   unsigned BufferStride[MAX_FEEDBACK_ATTRIBS];
 };
 
 /**