Query the framebuffer stencil bits instead of assuming it's global

Previously when the context was initialised Cogl would query the
number of stencil bits and set a private feature flag to mark that it
can use the buffer for clipping if there was at least 3. The problem
with this is that the number of stencil bits returned by
GL_STENCIL_BITS depends on the currently bound framebuffer. This patch
adds an internal function to query the number of stencil bits in a
framebuffer and makes it use that instead when determining whether it
can push the clip using the stencil buffer.

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

(cherry picked from commit e928d21516a6c07798655341f4f0f8e3c1d1686c)

7 files changed, 55 insertions, 38 deletions

diff --git a/cogl/cogl-framebuffer-private.h b/cogl/cogl-framebuffer-private.h
index 49800039..267dbf61 100644
--- a/cogl/cogl-framebuffer-private.h
+++ b/cogl/cogl-framebuffer-private.h
@@ -112,6 +112,7 @@ typedef struct
   int green;
   int alpha;
   int depth;
+  int stencil;
 } CoglFramebufferBits;
 
 struct _CoglFramebuffer
@@ -471,4 +472,18 @@ _cogl_framebuffer_read_pixels_into_bitmap (CoglFramebuffer *framebuffer,
                                            CoglBitmap *bitmap,
                                            CoglError **error);
 
+/*
+ * _cogl_framebuffer_get_stencil_bits:
+ * @framebuffer: a pointer to a #CoglFramebuffer
+ *
+ * Retrieves the number of stencil bits of @framebuffer
+ *
+ * Return value: the number of bits
+ *
+ * Since: 2.0
+ * Stability: unstable
+ */
+int
+_cogl_framebuffer_get_stencil_bits (CoglFramebuffer *framebuffer);
+
 #endif /* __COGL_FRAMEBUFFER_PRIVATE_H */
diff --git a/cogl/cogl-framebuffer.c b/cogl/cogl-framebuffer.c
index 5fb626d2..36962b64 100644
--- a/cogl/cogl-framebuffer.c
+++ b/cogl/cogl-framebuffer.c
@@ -1144,6 +1144,17 @@ cogl_framebuffer_get_depth_bits (CoglFramebuffer *framebuffer)
   return bits.depth;
 }
 
+int
+_cogl_framebuffer_get_stencil_bits (CoglFramebuffer *framebuffer)
+{
+  CoglContext *ctx = framebuffer->context;
+  CoglFramebufferBits bits;
+
+  ctx->driver_vtable->framebuffer_query_bits (framebuffer, &bits);
+
+  return bits.stencil;
+}
+
 CoglColorMask
 cogl_framebuffer_get_color_mask (CoglFramebuffer *framebuffer)
 {
diff --git a/cogl/cogl-private.h b/cogl/cogl-private.h
index eb104dc5..ce47eec1 100644
--- a/cogl/cogl-private.h
+++ b/cogl/cogl-private.h
@@ -35,28 +35,27 @@ typedef enum
 {
   COGL_PRIVATE_FEATURE_TEXTURE_2D_FROM_EGL_IMAGE = 1L<<0,
   COGL_PRIVATE_FEATURE_MESA_PACK_INVERT = 1L<<1,
-  COGL_PRIVATE_FEATURE_STENCIL_BUFFER = 1L<<2,
-  COGL_PRIVATE_FEATURE_OFFSCREEN_BLIT = 1L<<3,
-  COGL_PRIVATE_FEATURE_FOUR_CLIP_PLANES = 1L<<4,
-  COGL_PRIVATE_FEATURE_PBOS = 1L<<5,
-  COGL_PRIVATE_FEATURE_VBOS = 1L<<6,
-  COGL_PRIVATE_FEATURE_EXT_PACKED_DEPTH_STENCIL = 1L<<7,
-  COGL_PRIVATE_FEATURE_OES_PACKED_DEPTH_STENCIL = 1L<<8,
-  COGL_PRIVATE_FEATURE_TEXTURE_FORMAT_BGRA8888 = 1L<<9,
-  COGL_PRIVATE_FEATURE_UNPACK_SUBIMAGE = 1L<<10,
-  COGL_PRIVATE_FEATURE_SAMPLER_OBJECTS = 1L<<11,
-  COGL_PRIVATE_FEATURE_FIXED_FUNCTION = 1L<<12,
-  COGL_PRIVATE_FEATURE_READ_PIXELS_ANY_FORMAT = 1L<<13,
-  COGL_PRIVATE_FEATURE_ANY_GL = 1L<<14,
-  COGL_PRIVATE_FEATURE_ALPHA_TEST = 1L<<15,
-  COGL_PRIVATE_FEATURE_FORMAT_CONVERSION = 1L<<16,
-  COGL_PRIVATE_FEATURE_QUADS = 1L<<17,
-  COGL_PRIVATE_FEATURE_BLEND_CONSTANT = 1L<<18,
-  COGL_PRIVATE_FEATURE_QUERY_FRAMEBUFFER_BITS = 1L<<19,
-  COGL_PRIVATE_FEATURE_BUILTIN_POINT_SIZE_UNIFORM = 1L<<20,
-  COGL_PRIVATE_FEATURE_QUERY_TEXTURE_PARAMETERS = 1L<<21,
-  COGL_PRIVATE_FEATURE_ALPHA_TEXTURES = 1L<<22,
-  COGL_PRIVATE_FEATURE_TEXTURE_SWIZZLE = 1L<<23
+  COGL_PRIVATE_FEATURE_OFFSCREEN_BLIT = 1L<<2,
+  COGL_PRIVATE_FEATURE_FOUR_CLIP_PLANES = 1L<<3,
+  COGL_PRIVATE_FEATURE_PBOS = 1L<<4,
+  COGL_PRIVATE_FEATURE_VBOS = 1L<<5,
+  COGL_PRIVATE_FEATURE_EXT_PACKED_DEPTH_STENCIL = 1L<<6,
+  COGL_PRIVATE_FEATURE_OES_PACKED_DEPTH_STENCIL = 1L<<7,
+  COGL_PRIVATE_FEATURE_TEXTURE_FORMAT_BGRA8888 = 1L<<8,
+  COGL_PRIVATE_FEATURE_UNPACK_SUBIMAGE = 1L<<9,
+  COGL_PRIVATE_FEATURE_SAMPLER_OBJECTS = 1L<<10,
+  COGL_PRIVATE_FEATURE_FIXED_FUNCTION = 1L<<11,
+  COGL_PRIVATE_FEATURE_READ_PIXELS_ANY_FORMAT = 1L<<12,
+  COGL_PRIVATE_FEATURE_ANY_GL = 1L<<13,
+  COGL_PRIVATE_FEATURE_ALPHA_TEST = 1L<<14,
+  COGL_PRIVATE_FEATURE_FORMAT_CONVERSION = 1L<<15,
+  COGL_PRIVATE_FEATURE_QUADS = 1L<<16,
+  COGL_PRIVATE_FEATURE_BLEND_CONSTANT = 1L<<17,
+  COGL_PRIVATE_FEATURE_QUERY_FRAMEBUFFER_BITS = 1L<<18,
+  COGL_PRIVATE_FEATURE_BUILTIN_POINT_SIZE_UNIFORM = 1L<<19,
+  COGL_PRIVATE_FEATURE_QUERY_TEXTURE_PARAMETERS = 1L<<20,
+  COGL_PRIVATE_FEATURE_ALPHA_TEXTURES = 1L<<21,
+  COGL_PRIVATE_FEATURE_TEXTURE_SWIZZLE = 1L<<22
 } CoglPrivateFeatureFlags;
 
 /* Sometimes when evaluating pipelines, either during comparisons or
diff --git a/cogl/cogl2-path.c b/cogl/cogl2-path.c
index aa06c401..30b165c5 100644
--- a/cogl/cogl2-path.c
+++ b/cogl/cogl2-path.c
@@ -271,8 +271,8 @@ _cogl_path_fill_nodes_with_clipped_rectangle (CoglPath *path,
                                               CoglFramebuffer *framebuffer,
                                               CoglPipeline *pipeline)
 {
-  if (!(path->data->context->private_feature_flags &
-        COGL_PRIVATE_FEATURE_STENCIL_BUFFER))
+  /* We need at least three stencil bits to combine clips */
+  if (_cogl_framebuffer_get_stencil_bits (framebuffer) >= 3)
     {
       static CoglBool seen_warning = FALSE;
 
diff --git a/cogl/driver/gl/cogl-framebuffer-gl.c b/cogl/driver/gl/cogl-framebuffer-gl.c
index 753624a7..4cecf676 100644
--- a/cogl/driver/gl/cogl-framebuffer-gl.c
+++ b/cogl/driver/gl/cogl-framebuffer-gl.c
@@ -922,6 +922,8 @@ _cogl_framebuffer_init_bits (CoglFramebuffer *framebuffer)
               offsetof (CoglFramebufferBits, alpha) },
             { GL_DEPTH_ATTACHMENT, GL_FRAMEBUFFER_ATTACHMENT_DEPTH_SIZE,
               offsetof (CoglFramebufferBits, depth) },
+            { GL_STENCIL_ATTACHMENT, GL_FRAMEBUFFER_ATTACHMENT_STENCIL_SIZE,
+              offsetof (CoglFramebufferBits, stencil) },
           };
       int i;
 
@@ -943,11 +945,12 @@ _cogl_framebuffer_init_bits (CoglFramebuffer *framebuffer)
       GE( ctx, glGetIntegerv (GL_BLUE_BITS,  &framebuffer->bits.blue)  );
       GE( ctx, glGetIntegerv (GL_ALPHA_BITS, &framebuffer->bits.alpha) );
       GE( ctx, glGetIntegerv (GL_DEPTH_BITS, &framebuffer->bits.depth) );
+      GE( ctx, glGetIntegerv (GL_STENCIL_BITS, &framebuffer->bits.stencil) );
     }
 
 
   COGL_NOTE (OFFSCREEN,
-             "RGBA/D Bits for framebuffer[%p, %s]: %d, %d, %d, %d, %d",
+             "RGBA/D/S Bits for framebuffer[%p, %s]: %d, %d, %d, %d, %d, %d",
              framebuffer,
              framebuffer->type == COGL_FRAMEBUFFER_TYPE_OFFSCREEN
                ? "offscreen"
@@ -956,7 +959,8 @@ _cogl_framebuffer_init_bits (CoglFramebuffer *framebuffer)
              framebuffer->bits.blue,
              framebuffer->bits.green,
              framebuffer->bits.alpha,
-             framebuffer->bits.depth);
+             framebuffer->bits.depth,
+             framebuffer->bits.stencil);
 
   framebuffer->dirty_bitmasks = FALSE;
 }
diff --git a/cogl/driver/gl/gl/cogl-driver-gl.c b/cogl/driver/gl/gl/cogl-driver-gl.c
index 141371eb..6025d58f 100644
--- a/cogl/driver/gl/gl/cogl-driver-gl.c
+++ b/cogl/driver/gl/gl/cogl-driver-gl.c
@@ -360,7 +360,6 @@ _cogl_driver_update_features (CoglContext *ctx,
   CoglFeatureFlags flags = 0;
   char **gl_extensions;
   int max_clip_planes = 0;
-  int num_stencil_bits = 0;
   int gl_major = 0, gl_minor = 0;
 
   /* We have to special case getting the pointer to the glGetString*
@@ -450,11 +449,6 @@ _cogl_driver_update_features (CoglContext *ctx,
   if (_cogl_check_extension ("GL_MESA_pack_invert", gl_extensions))
     private_flags |= COGL_PRIVATE_FEATURE_MESA_PACK_INVERT;
 
-  GE( ctx, glGetIntegerv (GL_STENCIL_BITS, &num_stencil_bits) );
-  /* We need at least three stencil bits to combine clips */
-  if (num_stencil_bits > 2)
-    private_flags |= COGL_PRIVATE_FEATURE_STENCIL_BUFFER;
-
   GE( ctx, glGetIntegerv (GL_MAX_CLIP_PLANES, &max_clip_planes) );
   if (max_clip_planes >= 4)
     private_flags |= COGL_PRIVATE_FEATURE_FOUR_CLIP_PLANES;
diff --git a/cogl/driver/gl/gles/cogl-driver-gles.c b/cogl/driver/gl/gles/cogl-driver-gles.c
index 494b14ea..19202b4a 100644
--- a/cogl/driver/gl/gles/cogl-driver-gles.c
+++ b/cogl/driver/gl/gles/cogl-driver-gles.c
@@ -193,7 +193,6 @@ _cogl_driver_update_features (CoglContext *context,
   CoglPrivateFeatureFlags private_flags = 0;
   CoglFeatureFlags flags = 0;
   char **gl_extensions;
-  int num_stencil_bits = 0;
 
   /* We have to special case getting the pointer to the glGetString
      function because we need to use it to determine what functions we
@@ -233,11 +232,6 @@ _cogl_driver_update_features (CoglContext *context,
                                      -1 /* GL minor version */,
                                      gl_extensions);
 
-  GE( context, glGetIntegerv (GL_STENCIL_BITS, &num_stencil_bits) );
-  /* We need at least three stencil bits to combine clips */
-  if (num_stencil_bits > 2)
-    private_flags |= COGL_PRIVATE_FEATURE_STENCIL_BUFFER;
-
 #ifdef HAVE_COGL_GLES
   if (context->driver == COGL_DRIVER_GLES1)
     {