From: Mikko Rasa <tdb@tdb.fi>
Date: Sun, 6 Nov 2016 10:46:44 +0000 (+0200)
Subject: Restructure the extension detection code
X-Git-Url: http://git.tdb.fi/?p=libs%2Fgl.git;a=commitdiff_plain;h=e79c72cf90dacaa47d82d65d3e6c4252f055f454

Restructure the extension detection code

Extension disabling is now more forceful and will prevent the use of the
relevant functionality even if it was promoted to core.
---

diff --git a/scripts/extgen.py b/scripts/extgen.py
index e6edd42b..b3ed9c8f 100755
--- a/scripts/extgen.py
+++ b/scripts/extgen.py
@@ -517,17 +517,14 @@ for f in funcs:
 
 out.write("\nExtension::SupportLevel init_%s()\n{\n"%target_ext.name.lower())
 if core_version:
+	out.write("\tif(is_disabled(\"GL_%s\"))\n\t\treturn Extension::UNSUPPORTED;\n"%target_ext.name)
 	out.write("\tif(")
-	if deprecated_version and backport_ext:
-		out.write("(")
-	out.write("is_version_at_least(%d, %d)"%tuple(core_version))
-	if deprecated_version:
-		out.write(" && (get_gl_profile()!=CORE_PROFILE || !is_version_at_least(%d, %d))"%tuple(deprecated_version))
-		if backport_ext:
-			out.write(")")
 	if backport_ext:
-		out.write(" || is_supported(\"GL_%s\")"%backport_ext.name)
-	out.write(")\n\t{\n")
+		out.write("is_supported(\"GL_%s\") || "%backport_ext.name)
+	out.write("is_supported(Version(%d, %d)"%tuple(core_version))
+	if deprecated_version:
+		out.write(", Version(%d, %d)"%tuple(deprecated_version))
+	out.write("))\n\t{\n")
 	for f in funcs:
 		if target_api in f.supported_apis:
 			gpa_suffix = ""
diff --git a/source/extension.cpp b/source/extension.cpp
index fda183d2..b65172fc 100644
--- a/source/extension.cpp
+++ b/source/extension.cpp
@@ -93,6 +93,33 @@ bool is_supported(const string &ext)
 			}
 		}
 
+		init_done = true;
+	}
+
+	return extensions.count(ext);
+}
+
+bool is_supported(const Version &core_version, const Version &deprecated_version)
+{
+	const Version &version = get_gl_version();
+	if(deprecated_version && version>=deprecated_version && get_gl_profile()==CORE_PROFILE)
+		return false;
+	return (version>=core_version);
+}
+
+bool is_disabled(const string &ext)
+{
+	static set<string> disabled_exts;
+	static bool init_done = false;
+
+	if(!init_done)
+	{
+		if(const char *disable_ptr = getenv("MSPGL_DISABLE_EXTENSIONS"))
+		{
+			vector<string> disable = split(disable_ptr);
+			disabled_exts.insert(disable.begin(), disable.end());
+		}
+
 		if(const char *renderer_ptr = reinterpret_cast<const char *>(glGetString(GL_RENDERER)))
 		{
 			string renderer = renderer_ptr;
@@ -101,26 +128,19 @@ bool is_supported(const string &ext)
 				/* Radeon doesn't process NV_primitive_restart correctly and treats
 				the restart index as a normal element if the indices are stored in a
 				buffer. */
-				extensions.erase("GL_NV_primitive_restart");
+				disabled_exts.insert("GL_NV_primitive_restart");
 
 				/* AMD's uniform buffer objects only work with the core version of
 				shaders. */
 				if(get_gl_version()<Version(2, 0))
-					extensions.erase("GL_ARB_uniform_buffer_object");
+					disabled_exts.insert("GL_ARB_uniform_buffer_object");
 			}
 		}
 
-		if(const char *disable_ptr = getenv("MSPGL_DISABLE_EXTENSIONS"))
-		{
-			vector<string> disable = split(disable_ptr);
-			for(vector<string>::const_iterator i=disable.begin(); i!=disable.end(); ++i)
-				extensions.erase(*i);
-		}
-
 		init_done = true;
 	}
 
-	return extensions.count(ext);
+	return disabled_exts.count(ext);
 }
 
 GLApi get_gl_api()
@@ -207,11 +227,6 @@ const Version &get_glsl_version()
 	return version;
 }
 
-bool is_version_at_least(unsigned a, unsigned b)
-{
-	return get_gl_version()>=Version(a, b);
-}
-
 ExtFunc *get_proc_address(const string &name)
 {
 #if defined(WIN32)
diff --git a/source/extension.h b/source/extension.h
index b44d8900..1b149367 100644
--- a/source/extension.h
+++ b/source/extension.h
@@ -30,6 +30,7 @@ struct Version
 
 	bool operator>=(const Version &) const;
 	bool operator<(const Version &o) const { return !(*this>=o); }
+	operator bool() const { return major || minor; }
 };
 
 
@@ -67,9 +68,17 @@ struct Require
 
 typedef void ExtFunc();
 
-/** Indicates whether an extension is supported. */
+/** Checks for extension support.  Only intended for internal use. */
 bool is_supported(const std::string &);
 
+/** Checks for OpenGL version support.  Only intended for internal use. */
+bool is_supported(const Version &, const Version & = Version());
+
+/** Indicates whether an extension has been disabled, either explicitly through
+the MSPGL_DISABLE_EXTENSIONS environment variable or implicitly as a workaround
+for a driver bug.  Only intended for internal use. */
+bool is_disabled(const std::string &);
+
 /** Returns the API for which the library was compiled. */
 GLApi get_gl_api();
 
@@ -82,9 +91,6 @@ const Version &get_gl_version();
 /** Returns the GLSL version number, as reported by the implementation. */
 const Version &get_glsl_version();
 
-/** Indicates whether the OpenGL version is at least a.b. */
-bool is_version_at_least(unsigned a, unsigned b);
-
 /** Returns the address of an extension function.  Only indended for internal
 use. */
 ExtFunc *get_proc_address(const std::string &);