From 011bbfd451ef9df13ee66490a3b2760e77536016 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Branimir=20Karad=C5=BEi=C4=87?= <branimirkaradzic@gmail.com>
Date: Tue, 5 Jan 2016 21:06:42 -0800
Subject: [PATCH] GL: Added different code path when glGetString(GL_EXTENSIONS)
 returns NULL.

---
 src/glimports.h     |  2 ++
 src/renderer_gl.cpp | 77 +++++++++++++++++++++++++++------------------
 2 files changed, 49 insertions(+), 30 deletions(-)

diff --git a/src/glimports.h b/src/glimports.h
index 5891bd55..bcc114d1 100644
--- a/src/glimports.h
+++ b/src/glimports.h
@@ -149,6 +149,7 @@ typedef void           (GL_APIENTRYP PFNGLGETQUERYOBJECTUI64VPROC) (GLuint id, G
 typedef void           (GL_APIENTRYP PFNGLGETSHADERINFOLOGPROC) (GLuint shader, GLsizei bufSize, GLsizei *length, GLchar *infoLog);
 typedef void           (GL_APIENTRYP PFNGLGETSHADERIVPROC) (GLuint shader, GLenum pname, GLint *params);
 typedef const GLubyte* (GL_APIENTRYP PFNGLGETSTRINGPROC) (GLenum name);
+typedef const GLubyte* (GL_APIENTRYP PFNGLGETSTRINGIPROC) (GLenum name, GLuint index);
 typedef GLint          (GL_APIENTRYP PFNGLGETUNIFORMLOCATIONPROC) (GLuint program, const GLchar *name);
 typedef void           (GL_APIENTRYP PFNGLINVALIDATEFRAMEBUFFERPROC) (GLenum target, GLsizei numAttachments, const GLenum *attachments);
 typedef void           (GL_APIENTRYP PFNGLLINKPROGRAMPROC) (GLuint program);
@@ -332,6 +333,7 @@ GL_IMPORT______(true,  PFNGLGETQUERYOBJECTUI64VPROC,               glGetQueryObj
 GL_IMPORT______(false, PFNGLGETSHADERIVPROC,                       glGetShaderiv);
 GL_IMPORT______(false, PFNGLGETSHADERINFOLOGPROC,                  glGetShaderInfoLog);
 GL_IMPORT______(false, PFNGLGETSTRINGPROC,                         glGetString);
+GL_IMPORT______(true,  PFNGLGETSTRINGIPROC,                        glGetStringi);
 GL_IMPORT______(false, PFNGLGETUNIFORMLOCATIONPROC,                glGetUniformLocation);
 #if BGFX_CONFIG_RENDERER_OPENGL || !(BGFX_CONFIG_RENDERER_OPENGLES < 30)
 GL_IMPORT______(true,  PFNGLINVALIDATEFRAMEBUFFERPROC,             glInvalidateFramebuffer);
diff --git a/src/renderer_gl.cpp b/src/renderer_gl.cpp
index 24d36261..9738a713 100644
--- a/src/renderer_gl.cpp
+++ b/src/renderer_gl.cpp
@@ -1209,6 +1209,34 @@ namespace bgfx { namespace gl
 		_minFilter = s_textureFilterMin[min][_hasMips ? mip+1 : 0];
 	}
 
+	void updateExtension(const char* _name)
+	{
+		bool supported = false;
+		for (uint32_t ii = 0; ii < Extension::Count; ++ii)
+		{
+			Extension& extension = s_extension[ii];
+			if (!extension.m_supported
+			&&  extension.m_initialize)
+			{
+				const char* ext = _name;
+				if (0 == strncmp(ext, "GL_", 3) ) // skip GL_
+				{
+					ext += 3;
+				}
+
+				if (0 == strcmp(ext, extension.m_name) )
+				{
+					extension.m_supported = true;
+					supported = true;
+					break;
+				}
+			}
+		}
+
+		BX_TRACE("GL_EXTENSION %3d%s: %s", index, supported ? " (supported)" : "", _name);
+		BX_UNUSED(supported);
+	}
+
 	struct RendererContextGL : public RendererContextI
 	{
 		RendererContextGL()
@@ -1365,42 +1393,31 @@ namespace bgfx { namespace gl
 						strncpy(name, pos, len);
 						name[len] = '\0';
 
-						bool supported = false;
-						for (uint32_t ii = 0; ii < Extension::Count; ++ii)
-						{
-							Extension& extension = s_extension[ii];
-							if (!extension.m_supported
-							&&  extension.m_initialize)
-							{
-								const char* ext = name;
-								if (0 == strncmp(ext, "GL_", 3) ) // skip GL_
-								{
-									ext += 3;
-								}
-
-								if (0 == strcmp(ext, extension.m_name) )
-								{
-									extension.m_supported = true;
-									supported = true;
-									break;
-								}
-							}
-						}
-
-						BX_TRACE("GL_EXTENSION %3d%s: %s", index, supported ? " (supported)" : "", name);
-						BX_UNUSED(supported);
+						updateExtension(name);
 
 						pos += len+1;
 						++index;
 					}
+				}
+				else if (NULL != glGetStringi)
+				{
+					GLint numExtensions = 0;
+					glGetIntegerv(GL_NUM_EXTENSIONS, &numExtensions);
+					glGetError(); // ignore error if glGetString returns NULL.
 
-					BX_TRACE("Supported extensions:");
-					for (uint32_t ii = 0; ii < Extension::Count; ++ii)
+					for (GLint index = 0; index < numExtensions; ++index)
 					{
-						if (s_extension[ii].m_supported)
-						{
-							BX_TRACE("\t%2d: %s", ii, s_extension[ii].m_name);
-						}
+						const char* name = (const char*)glGetStringi(GL_EXTENSIONS, index);
+						updateExtension(name);
+					}
+				}
+
+				BX_TRACE("Supported extensions:");
+				for (uint32_t ii = 0; ii < Extension::Count; ++ii)
+				{
+					if (s_extension[ii].m_supported)
+					{
+						BX_TRACE("\t%2d: %s", ii, s_extension[ii].m_name);
 					}
 				}
 			}