i965: Enable the ARB_transform_feedback3 extension on Gen7+.

This extension is written a bit strangely.  Although it introduces the
concept of multiple transform feedback streams, it doesn't actually
provide more than a single stream.

The ARB_gpu_shader5 extension is what introduces the ability to write to
streams other than stream #0 and increases the required number of streams.

Since we don't yet support ARB_gpu_shader5, we can safely enable
ARB_transform_feedback3 even though we only support a single stream.
This does provide some useful functionality: applications can now use
more than one interleaved transform feedback buffer.

v2: Only expose the extension if ARB_transform_feedback2 is also
    available, to avoid confusing applications (suggested by Ian).

Signed-off-by: Kenneth Graunke <[email protected]>
Reviewed-by: Ian Romanick <[email protected]>

1 files changed, 1 insertions, 0 deletions

diff --git a/src/mesa/drivers/dri/i965/intel_extensions.c b/src/mesa/drivers/dri/i965/intel_extensions.c
index 337e7e87c4f..31e15bbfb48 100644
--- a/src/mesa/drivers/dri/i965/intel_extensions.c
+++ b/src/mesa/drivers/dri/i965/intel_extensions.c
@@ -230,6 +230,7 @@ intelInitExtensions(struct gl_context *ctx)
       ctx->Extensions.ARB_conservative_depth = true;
       if (can_do_pipelined_register_writes(brw)) {
          ctx->Extensions.ARB_transform_feedback2 = true;
+         ctx->Extensions.ARB_transform_feedback3 = true;
       }
    }