Fix flushing the stencil viewport clipping workaround

There were two problems with the stencil viewport clip workaround
introduced in afc5daab8:

• When the viewport is changed the current clip state is not marked as
  dirty. That means that when the framebuffer state is next flushed it
  would continue to use the stencil from the previous viewport.

• When the viewport is automatically updated due to the window being
  resized the viewport age was not incremented so the clip state
  wouldn't be flushed.

I noticed the bugs by running cogl-sdl2-hello.

This patch makes it so that the clip state is dirtied in
cogl_framebuffer_set_viewport if the workaround is enabled.

The automatic viewport changing code now just calls
cogl_framebuffer_set_viewport instead of directly prodding the
viewport values. This has the side-effect that it will also cause the
journal to be flushed. This seems like the right thing to do anyway
and presumably there would have been a bug before where it wouldn't
have flushed the journal, although presumably this is extremely
unlikely because it would have to have done a resize in the middle of
painting the scene.

Reviewed-by: Robert Bragg <robert@linux.intel.com>

2 files changed, 10 insertions, 14 deletions

diff --git a/cogl/cogl-framebuffer.c b/cogl/cogl-framebuffer.c
index 49d43644..54b7797f 100644
--- a/cogl/cogl-framebuffer.c
+++ b/cogl/cogl-framebuffer.c
@@ -448,6 +448,8 @@ cogl_framebuffer_set_viewport (CoglFramebuffer *framebuffer,
                                float width,
                                float height)
 {
+  CoglContext *context = framebuffer->context;
+
   _COGL_RETURN_IF_FAIL (width > 0 && height > 0);
 
   if (framebuffer->viewport_x == x &&
@@ -464,9 +466,13 @@ cogl_framebuffer_set_viewport (CoglFramebuffer *framebuffer,
   framebuffer->viewport_height = height;
   framebuffer->viewport_age++;
 
-  if (framebuffer->context->current_draw_buffer == framebuffer)
-    framebuffer->context->current_draw_buffer_changes |=
-      COGL_FRAMEBUFFER_STATE_VIEWPORT;
+  if (context->current_draw_buffer == framebuffer)
+    {
+      context->current_draw_buffer_changes |= COGL_FRAMEBUFFER_STATE_VIEWPORT;
+
+      if (context->needs_viewport_scissor_workaround)
+        context->current_draw_buffer_changes |= COGL_FRAMEBUFFER_STATE_CLIP;
+    }
 }
 
 float
diff --git a/cogl/cogl-onscreen.c b/cogl/cogl-onscreen.c
index 4aaa5de4..3c1e148d 100644
--- a/cogl/cogl-onscreen.c
+++ b/cogl/cogl-onscreen.c
@@ -387,17 +387,7 @@ _cogl_framebuffer_winsys_update_size (CoglFramebuffer *framebuffer,
   framebuffer->width = width;
   framebuffer->height = height;
 
-  framebuffer->viewport_x = 0;
-  framebuffer->viewport_y = 0;
-  framebuffer->viewport_width = width;
-  framebuffer->viewport_height = height;
-
-  /* If the framebuffer being updated is the current framebuffer we
-   * mark the viewport state as changed so it will be updated the next
-   * time _cogl_framebuffer_flush_state() is called. */
-  if (framebuffer->context->current_draw_buffer == framebuffer)
-    framebuffer->context->current_draw_buffer_changes |=
-      COGL_FRAMEBUFFER_STATE_VIEWPORT;
+  cogl_framebuffer_set_viewport (framebuffer, 0, 0, width, height);
 }
 
 void