Add API to control per-framebuffer depth writing

Add framebuffer methods cogl_framebuffer_[gs]et_depth_write_enabled()
and backend bits to pass the state on to glDepthMask().

This allows us to enable or disable depth writing per-framebuffer, which
if disabled saves us some work in glClear(). When rendering, the flag
is combined with the pipeline's depth writing flag using a logical AND.

Depth writing is enabled by default.

https://bugzilla.gnome.org/show_bug.cgi?id=709827

Reviewed-by: Robert Bragg <robert@linux.intel.com>
(cherry picked from commit 71406438c5357eb4e0ef03e940c5456a536602a0)

1 files changed, 33 insertions, 0 deletions

diff --git a/cogl/cogl-framebuffer.h b/cogl/cogl-framebuffer.h
index e3dad9fa..45f01571 100644
--- a/cogl/cogl-framebuffer.h
+++ b/cogl/cogl-framebuffer.h
@@ -758,6 +758,39 @@ cogl_framebuffer_set_dither_enabled (CoglFramebuffer *framebuffer,
                                      CoglBool dither_enabled);
 
 /**
+ * cogl_framebuffer_get_depth_write_enabled:
+ * @framebuffer: a pointer to a #CoglFramebuffer
+ *
+ * Queries whether depth buffer writing is enabled for @framebuffer. This
+ * can be controlled via cogl_framebuffer_set_depth_write_enabled().
+ *
+ * Return value: %TRUE if depth writing is enabled or %FALSE if not.
+ * Since: 1.18
+ * Stability: unstable
+ */
+CoglBool
+cogl_framebuffer_get_depth_write_enabled (CoglFramebuffer *framebuffer);
+
+/**
+ * cogl_framebuffer_set_depth_write_enabled:
+ * @framebuffer: a pointer to a #CoglFramebuffer
+ * @depth_write_enabled: %TRUE to enable depth writing or %FALSE to disable
+ *
+ * Enables or disables depth buffer writing when rendering to @framebuffer.
+ * If depth writing is enabled for both the framebuffer and the rendering
+ * pipeline, and the framebuffer has an associated depth buffer, depth
+ * information will be written to this buffer during rendering.
+ *
+ * Depth buffer writing is enabled by default.
+ *
+ * Since: 1.18
+ * Stability: unstable
+ */
+void
+cogl_framebuffer_set_depth_write_enabled (CoglFramebuffer *framebuffer,
+                                          CoglBool depth_write_enabled);
+
+/**
  * cogl_framebuffer_get_color_mask:
  * @framebuffer: a pointer to a #CoglFramebuffer
  *