[Mesa-dev] [PATCH 28/41] main: Nameless texture creation and deletion. Does not affect normal creation and deletion paths.

[Laura Ekstrand]

In implementing ARB_DIRECT_STATE_ACCESS functions, it is often necessary to
abstract the functionality of a traditional GL API function into a backend
that both the traditional and dsa API functions can share.  For instance,
glTexParameteri and glTextureParameteri both call _mesa_texture_parameteri,
which takes a context object and a texture object as arguments.

The existance of such backend functions provides the opportunity for
driver internals (such as meta) to pass around the actual texture object
rather than its ID or target, saving on texture object storage and look-up
overhead.

This patch provides nameless texture creation and deletion for meta.  This
will be used in an upcoming refactor of meta.
---
 src/mesa/main/texobj.c | 60 ++++++++++++++++++++++++++++++++++++++++++++++++++
 src/mesa/main/texobj.h |  7 ++++++
 2 files changed, 67 insertions(+)

diff --git a/src/mesa/main/texobj.c b/src/mesa/main/texobj.c
index eb16f47..01088e3 100644
--- a/src/mesa/main/texobj.c
+++ b/src/mesa/main/texobj.c
@@ -1102,6 +1102,27 @@ invalidate_tex_image_error_check(struct gl_context *ctx, GLuint texture,
    return t;
 }
 
+/**
+ * Wrapper for the driver function. Need this because _mesa_new_texture_object
+ * permits a target of 0 and does not initialize targetIndex.
+ */
+struct gl_texture_object *
+_mesa_create_nameless_texture( struct gl_context *ctx, GLenum target )
+{
+      struct gl_texture_object *texObj = NULL;
+      GLint targetIndex;
+
+      if (target == 0)
+         return texObj;
+
+      texObj = ctx->Driver.NewTextureObject(ctx, 0, target);
+      targetIndex = _mesa_tex_target_to_index(ctx, texObj->Target);
+      assert(targetIndex < NUM_TEXTURE_TARGETS);
+      texObj->TargetIndex = targetIndex;
+
+      return texObj;
+}
+
 /* Helper function for glCreateTextures and glGenTextures. Need this because
  * glCreateTextures should throw errors if target = 0. This is not exposed to
  * the rest of Mesa to encourage Mesa internals to use nameless textures,
@@ -1405,6 +1426,45 @@ _mesa_DeleteTextures( GLsizei n, const GLuint *textures)
    }
 }
 
+/**
+ * This deletes a texObj without altering the hash table.
+ */
+void
+_mesa_delete_nameless_texture( struct gl_context *ctx,
+                               struct gl_texture_object *texObj )
+{
+   FLUSH_VERTICES(ctx, 0);
+   if (texObj) {
+      _mesa_lock_texture(ctx, texObj);
+
+      /* Check if texture is bound to any framebuffer objects.
+       * If so, unbind.
+       * See section 4.4.2.3 of GL_EXT_framebuffer_object.
+       */
+      unbind_texobj_from_fbo(ctx, texObj);
+
+      /* Check if this texture is currently bound to any texture units.
+       * If so, unbind it.
+       */
+      unbind_texobj_from_texunits(ctx, texObj);
+
+      /* Check if this texture is currently bound to any shader
+       * image unit.  If so, unbind it.
+       * See section 3.9.X of GL_ARB_shader_image_load_store.
+       */
+      unbind_texobj_from_image_units(ctx, texObj);
+
+      _mesa_unlock_texture(ctx, texObj);
+
+      ctx->NewState |= _NEW_TEXTURE;
+
+      /* Unreference the texobj.  If refcount hits zero, the texture
+       * will be deleted.
+       */
+      _mesa_reference_texobj(&texObj, NULL);
+   }
+}
+
 
 /**
  * Convert a GL texture target enum such as GL_TEXTURE_2D or GL_TEXTURE_3D
diff --git a/src/mesa/main/texobj.h b/src/mesa/main/texobj.h
index 34daebb..3a62d63 100644
--- a/src/mesa/main/texobj.h
+++ b/src/mesa/main/texobj.h
@@ -190,6 +190,13 @@ _mesa_unlock_context_textures( struct gl_context *ctx );
 extern void
 _mesa_lock_context_textures( struct gl_context *ctx );
 
+extern struct gl_texture_object *
+_mesa_create_nameless_texture( struct gl_context *ctx, GLenum target );
+
+extern void
+_mesa_delete_nameless_texture( struct gl_context *ctx,
+                               struct gl_texture_object *texObj );
+
 extern void
 _mesa_bind_texture_unit( struct gl_context *ctx,
                          GLuint unit,
-- 
2.1.0