svga: fix the rasterizer state resets

draw module calls back into the driver and sets certain parts
of the state to whatever it needs, unfortunately unless you
get the ordering of calls to draw just right you'll end up
reseting your own driver state. That's what was happening to us
draw module would under certain conditions reset our own driver
state.

Reviewed-by: Brian Paul <[email protected]>

1 files changed, 15 insertions, 0 deletions

diff --git a/src/gallium/auxiliary/draw/draw_context.h b/src/gallium/auxiliary/draw/draw_context.h
index 02c176e8f4b..f3a3f232322 100644
--- a/src/gallium/auxiliary/draw/draw_context.h
+++ b/src/gallium/auxiliary/draw/draw_context.h
@@ -80,6 +80,21 @@ void draw_set_viewport_state( struct draw_context *draw,
 void draw_set_clip_state( struct draw_context *pipe,
                           const struct pipe_clip_state *clip );
 
+/**
+ * Sets the rasterization state used by the draw module.
+ * The rast_handle is used to pass the driver specific representation
+ * of the rasterization state. It's going to be used when the
+ * draw module sets the state back on the driver itself using the
+ * pipe::bind_rasterizer_state method.
+ *
+ * NOTE: if you're calling this function from within the pipe's
+ * bind_rasterizer_state you should always call it before binding
+ * the actual state - that's because the draw module can try to
+ * bind its own rasterizer state which would reset your newly
+ * set state. i.e. always do
+ * draw_set_rasterizer_state(driver->draw, state->pipe_state, state);
+ * driver->state.raster = state;
+ */
 void draw_set_rasterizer_state( struct draw_context *draw,
                                 const struct pipe_rasterizer_state *raster,
                                 void *rast_handle );