[Scummvm-git-logs] scummvm branch-2-8 -> 0e7aefa351afa028d44b6070616de1ad889f589a

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Summary:
0e7aefa351 OPENGL: Use GLAD version when available and check functions before use


Commit: 0e7aefa351afa028d44b6070616de1ad889f589a
    https://github.com/scummvm/scummvm/commit/0e7aefa351afa028d44b6070616de1ad889f589a
Author: Le Philousophe (lephilousophe at users.noreply.github.com)
Date: 2023-12-14T18:37:42+01:00

Commit Message:
OPENGL: Use GLAD version when available and check functions before use

When GLAD fails to parse version, glGetError is null and raises a
SIGSEGV.
Current version of GLAD has a bug while parsing extensions so there is a
workaround here which should disappear when it's fixed.

Changed paths:
    graphics/opengl/context.cpp


diff --git a/graphics/opengl/context.cpp b/graphics/opengl/context.cpp
index cde9011a241..ae8105129c4 100644
--- a/graphics/opengl/context.cpp
+++ b/graphics/opengl/context.cpp
@@ -84,56 +84,77 @@ void Context::initialize(ContextType contextType) {
 	type = contextType;
 
 #ifdef USE_GLAD
+	int gladVersion;
 	switch (type) {
 	case kContextGL:
-		gladLoadGL(loadFunc);
+		gladVersion = gladLoadGL(loadFunc);
 		break;
 
 	case kContextGLES:
-		gladLoadGLES1(loadFunc);
+		gladVersion = gladLoadGLES1(loadFunc);
 		break;
 
 	case kContextGLES2:
-		gladLoadGLES2(loadFunc);
+		gladVersion = gladLoadGLES2(loadFunc);
 		break;
 
 	default:
+		gladVersion = 0;
 		break;
 	}
-#endif
 
-	const char *verString = (const char *)glGetString(GL_VERSION);
+	majorVersion = GLAD_VERSION_MAJOR(gladVersion);
+	minorVersion = GLAD_VERSION_MINOR(gladVersion);
 
-	if (!verString) {
-		majorVersion = minorVersion = 0;
-		warning("Could not parse fetch GL_VERSION: %d", glGetError());
-	} else if (type == kContextGL) {
-		// OpenGL version number is either of the form major.minor or major.minor.release,
-		// where the numbers all have one or more digits
-		if (sscanf(verString, "%d.%d", &majorVersion, &minorVersion) != 2) {
-			majorVersion = minorVersion = 0;
-			warning("Could not parse GL version '%s'", verString);
+	if (!gladVersion)
+		// If gladVersion is 0 it either means:
+		// - loading failed and glad didn't even set up core functions
+		// - we are hit by GLAD bug #446 which fails to parse some extensions
+		// In this case just try to do the parsing by ourselves
+#endif
+	{
+		if (!glGetString) {
+			error("Couldn't initialize OpenGL");
 		}
-	} else if (type == kContextGLES) {
-		// The form of the string is "OpenGL ES-<profile> <major>.<minor>",
-		// where <profile> is either "CM" (Common) or "CL" (Common-Lite),
-		// and <major> and <minor> are integers.
-		char profile[3];
-		if (sscanf(verString, "OpenGL ES-%2s %d.%d", profile,
-					&majorVersion, &minorVersion) != 3) {
+
+		const char *verString = (const char *)glGetString(GL_VERSION);
+
+		if (!verString) {
 			majorVersion = minorVersion = 0;
-			warning("Could not parse GL ES version '%s'", verString);
-		}
-	} else if (type == kContextGLES2) {
-		// The version is of the form
-		// OpenGL<space>ES<space><version number><space><vendor-specific information>
-		// version number format is not defined
-		// There is only OpenGL ES 2.0 anyway
-		if (sscanf(verString, "OpenGL ES %d.%d", &majorVersion, &minorVersion) != 2) {
-			minorVersion = 0;
-			if (sscanf(verString, "OpenGL ES %d ", &majorVersion) != 1) {
-				majorVersion = 0;
-				warning("Could not parse GL ES 2 version '%s'", verString);
+			int errorCode = 0;
+			if (glGetError) {
+				errorCode = glGetError();
+			}
+			warning("Could not fetch GL_VERSION: %d", errorCode);
+			return;
+		} else if (type == kContextGL) {
+			// OpenGL version number is either of the form major.minor or major.minor.release,
+			// where the numbers all have one or more digits
+			if (sscanf(verString, "%d.%d", &majorVersion, &minorVersion) != 2) {
+				majorVersion = minorVersion = 0;
+				warning("Could not parse GL version '%s'", verString);
+			}
+		} else if (type == kContextGLES) {
+			// The form of the string is "OpenGL ES-<profile> <major>.<minor>",
+			// where <profile> is either "CM" (Common) or "CL" (Common-Lite),
+			// and <major> and <minor> are integers.
+			char profile[3];
+			if (sscanf(verString, "OpenGL ES-%2s %d.%d", profile,
+						&majorVersion, &minorVersion) != 3) {
+				majorVersion = minorVersion = 0;
+				warning("Could not parse GL ES version '%s'", verString);
+			}
+		} else if (type == kContextGLES2) {
+			// The version is of the form
+			// OpenGL<space>ES<space><version number><space><vendor-specific information>
+			// version number format is not defined
+			// There is only OpenGL ES 2.0 anyway
+			if (sscanf(verString, "OpenGL ES %d.%d", &majorVersion, &minorVersion) != 2) {
+				minorVersion = 0;
+				if (sscanf(verString, "OpenGL ES %d ", &majorVersion) != 1) {
+					majorVersion = 0;
+					warning("Could not parse GL ES 2 version '%s'", verString);
+				}
 			}
 		}
 	}
@@ -294,7 +315,7 @@ void Context::initialize(ContextType contextType) {
 	const char *glslVersionString = (const char *)glGetString(GL_SHADING_LANGUAGE_VERSION);
 
 	// Log features supported by GL context.
-	debug(5, "OpenGL version: %s", verString);
+	debug(5, "OpenGL version: %s", glGetString(GL_VERSION));
 	debug(5, "OpenGL vendor: %s", glGetString(GL_VENDOR));
 	debug(5, "OpenGL renderer: %s", glGetString(GL_RENDERER));
 	debug(5, "OpenGL: version %d.%d", majorVersion, minorVersion);