Support using Glad instead of GLEW

src/CMakeLists.txt

@@ -40,6 +40,7 @@ set(BUILD_ADDITIONAL_PLUGINS
 
 option(ALLOW_BUNDLED_EIGEN "Allow use of bundled Eigen source" ON)
 option(ALLOW_BUNDLED_GLEW "Allow use of bundled GLEW source" ON)
+option(ALLOW_BUNDLED_GLAD "Allow use of bundled glad source" ON)
 option(ALLOW_BUNDLED_NEWUOA "Allow use of bundled newuoa source" ON)
 option(ALLOW_BUNDLED_LEVMAR "Allow use of bundled levmar source" ON)
 option(ALLOW_BUNDLED_LIB3DS "Allow use of bundled lib3ds source" ON)
@@ -57,6 +58,8 @@ option(ALLOW_SYSTEM_MUPARSER "Allow use of system-provided muparser" ON)
 option(ALLOW_SYSTEM_OPENCTM "Allow use of system-provided OpenCTM" ON)
 option(ALLOW_SYSTEM_QHULL "Allow use of system-provided QHull" ON)
 
+option(BUILD_PREFER_GLAD "If both glew and glad are available, prefer to use glad" OFF)
+
 ### Dependencies
 list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/cmake")
 message(STATUS "Searching for required components")
@@ -169,11 +172,24 @@ add_subdirectory(common)
 set(CMAKE_INSTALL_RPATH $ORIGIN/../${MESHLAB_LIB_INSTALL_DIR};$ORIGIN/../${CMAKE_INSTALL_LIBDIR})
 add_subdirectory(meshlab)
 add_subdirectory(meshlabserver)
-if (WIN32)
+if(WIN32)
     add_subdirectory(use_cpu_opengl)
 endif()
 set(CMAKE_INSTALL_RPATH)
 
+### Bits of vcglib directly included
+add_library(vcglib_trackball STATIC ${VCGDIR}/wrap/gui/trackball.cpp ${VCGDIR}/wrap/gui/trackmode.cpp
+                                    ${VCGDIR}/wrap/gui/trackball.h ${VCGDIR}/wrap/gui/trackmode.h)
+target_link_libraries(vcglib_trackball PUBLIC external-opengl PRIVATE Qt5::Core Qt5::OpenGL)
+if(MESHLAB_USE_GLAD)
+    # Force include to use GLAD instead of GLEW without modifying vcglib.
+    if(MSVC)
+        target_compile_options(vcglib_trackball PRIVATE /FI"glad/glad.h")
+    else()
+        target_compile_options(vcglib_trackball PRIVATE -include "glad/glad.h")
+    endif()
+endif()
+
 ### Plugin subdirectories
 if(BUILD_MINI)
     # mini

src/common/CMakeLists.txt

@@ -3,7 +3,7 @@
 
 ### Generated file! Edit the templates in src/templates then re-run ./make-cmake.py
 
-if (EXISTS ../../ML_VERSION)
+if(EXISTS ../../ML_VERSION)
     file(READ ../../ML_VERSION MESHLAB_VERSION)
     add_definitions(-DMESHLAB_VERSION=${MESHLAB_VERSION})
 endif()
@@ -30,6 +30,8 @@ set(HEADERS
     GLLogStream.h
     filterparameter.h
     filterscript.h
+    gl_defs.h
+    glu_defs.h
     interfaces.h
     meshlabdocumentbundler.h
     meshlabdocumentxml.h
@@ -63,7 +65,7 @@ target_link_libraries(
            Qt5::Widgets
            Qt5::Xml
            Qt5::XmlPatterns
-           external-glew
+           external-opengl
     PRIVATE external-jhead)
 
 set_property(TARGET common PROPERTY FOLDER Core)

src/common/gl_defs.h

@@ -21,15 +21,56 @@
  *                                                                           *
  ****************************************************************************/
 
-#include "mlexception.h"
+#ifndef GL_DEFS_H
+#define GL_DEFS_H
+
+#ifdef MESHLAB_USE_GLAD
+#include <glad/glad.h>
+
+// Block loading of GLEW
+// #define __glew_h__
 
+#else
 #include <GL/glew.h>
+#endif
+
+#include "mlexception.h"
+
+// This string is searched for by an error handler, so it must be included
+// verbatim in all graphics-related errors.
+static const char MESHLAB_GL_ERROR_MSG[] =
+    "OpenGL extension initialization failed";
+
+#ifdef MESHLAB_USE_GLAD
+static inline bool initializeGLextensions_notThrowing() {
+    if (!gladLoadGL()) {
+        qWarning(MESHLAB_GL_ERROR_MSG);
+        return false;
+    }
+    return true;
+}
+
+static inline void initializeGLextensions() {
+    if (!gladLoadGL()) {
+        throw MLException(QString("%1\n").arg(MESHLAB_GL_ERROR_MSG));
+    }
+}
+
+#define MESHLAB_MAKE_EXTENSION_CHECKER(EXT)                                    \
+    static inline bool glExtensionsHas##EXT() { return GLAD_GL_##EXT; }
+
+// Work around GLEW-specific code in vcglib
+
+#define GLEW_ARB_uniform_buffer_object GLAD_GL_ARB_uniform_buffer_object
+#define GLEW_EXT_transform_feedback GLAD_GL_EXT_transform_feedback
+
+#else
 
 static inline bool initializeGLextensions_notThrowing() {
     glewExperimental = GL_TRUE;
     GLenum err = glewInit();
     if (err != GLEW_OK) {
-        qWarning("GLEW initialization failed: %s",
+        qWarning("%s: %s", MESHLAB_GL_ERROR_MSG,
                  (const char *)glewGetErrorString(err));
     }
     return err == GLEW_OK;
@@ -39,7 +80,32 @@ static inline void initializeGLextensions() {
     glewExperimental = GL_TRUE;
     GLenum err = glewInit();
     if (err != GLEW_OK) {
-        throw MLException(QString("GLEW initialization failed: %1\n")
+        throw MLException(QString("%1: %2\n")
+                              .arg(MESHLAB_GL_ERROR_MSG)
                               .arg((const char *)glewGetErrorString(err)));
     }
 }
+
+#define MESHLAB_MAKE_EXTENSION_CHECKER(EXT)                                    \
+    static inline bool glExtensionsHas##EXT() { return GLEW_##EXT; }
+
+#endif
+
+MESHLAB_MAKE_EXTENSION_CHECKER(ARB_draw_buffers)
+MESHLAB_MAKE_EXTENSION_CHECKER(ARB_fragment_program)
+MESHLAB_MAKE_EXTENSION_CHECKER(ARB_fragment_shader)
+MESHLAB_MAKE_EXTENSION_CHECKER(ARB_shader_objects)
+MESHLAB_MAKE_EXTENSION_CHECKER(ARB_shading_language_100)
+MESHLAB_MAKE_EXTENSION_CHECKER(ARB_texture_cube_map)
+MESHLAB_MAKE_EXTENSION_CHECKER(ARB_texture_float)
+MESHLAB_MAKE_EXTENSION_CHECKER(ARB_texture_non_power_of_two)
+MESHLAB_MAKE_EXTENSION_CHECKER(ARB_vertex_buffer_object)
+MESHLAB_MAKE_EXTENSION_CHECKER(ARB_vertex_program)
+MESHLAB_MAKE_EXTENSION_CHECKER(ARB_vertex_shader)
+MESHLAB_MAKE_EXTENSION_CHECKER(EXT_framebuffer_object)
+MESHLAB_MAKE_EXTENSION_CHECKER(EXT_gpu_shader4)
+MESHLAB_MAKE_EXTENSION_CHECKER(EXT_vertex_shader)
+
+#undef MESHLAB_MAKE_EXTENSION_CHECKER
+
+#endif // !GL_DEFS_H

src/common/glu_defs.h

@@ -0,0 +1,35 @@
+/****************************************************************************
+ * MeshLab                                                           o o     *
+ * An extendible mesh processor                                    o     o   *
+ *                                                                _   O  _   *
+ * Copyright(C) 2005, 2006                                          \/)\/    *
+ * Visual Computing Lab                                            /\/|      *
+ * ISTI - Italian National Research Council                           |      *
+ *                                                                    \      *
+ * All rights reserved.                                                      *
+ *                                                                           *
+ * This program is free software; you can redistribute it and/or modify      *
+ * it under the terms of the GNU General Public License as published by      *
+ * the Free Software Foundation; either version 2 of the License, or         *
+ * (at your option) any later version.                                       *
+ *                                                                           *
+ * This program is distributed in the hope that it will be useful,           *
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of            *
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the             *
+ * GNU General Public License (http://www.gnu.org/licenses/gpl.txt)          *
+ * for more details.                                                         *
+ *                                                                           *
+ ****************************************************************************/
+
+#ifndef GLU_DEFS_H
+#define GLU_DEFS_H
+
+#include "gl_defs.h"
+
+#ifdef __APPLE__
+#include <OpenGL/glu.h>
+#else
+#include <GL/glu.h>
+#endif
+
+#endif // !GLU_DEFS_H

src/common/meshmodel.h

@@ -23,7 +23,8 @@
 
 #ifndef MESHMODEL_H
 #define MESHMODEL_H
-#include <GL/glew.h>
+
+#include "gl_defs.h"
 
 #include <stdio.h>
 #include <time.h>

src/common/ml_shared_data_context.h

@@ -24,7 +24,7 @@
 #ifndef __ML_SHARED_DATA_CONTEXT_H
 #define __ML_SHARED_DATA_CONTEXT_H
 
-#include <GL/glew.h>
+#include "gl_defs.h"
 #include <QTimer>
 
 #include "ml_mesh_type.h"

src/external.cmake

@@ -21,7 +21,7 @@ target_compile_definitions(external-jhead PRIVATE main=jhead_main)
 target_include_directories(external-jhead PUBLIC ${JHEAD_DIR})
 set_property(TARGET external-jhead PROPERTY FOLDER External)
 
-# GLEW - required
+# GLEW - either this or GLAD is required
 set(GLEW_DIR ${EXTERNAL_DIR}/glew-2.1.0)
 if(ALLOW_SYSTEM_GLEW AND TARGET GLEW::GLEW)
     message(STATUS "- glew - using system-provided library")
@@ -50,10 +50,56 @@ elseif(ALLOW_BUNDLED_GLEW AND EXISTS "${GLEW_DIR}/src/glew.c")
         target_link_libraries(external-glew PUBLIC OpenGL::GLX)
     endif()
     set_property(TARGET external-glew PROPERTY FOLDER External)
+endif()
+
+# glad - either this or GLEW is required
+set(GLAD_DIR ${EXTERNAL_DIR}/glad)
+if(ALLOW_BUNDLED_GLAD AND EXISTS "${GLAD_DIR}/src/glad.c")
+    message(STATUS "- glad - using bundled source")
+    add_library(external-glad STATIC "${GLAD_DIR}/src/glad.c")
+    target_compile_definitions(external-glad PUBLIC MESHLAB_USE_GLAD)
+    target_include_directories(external-glad SYSTEM PUBLIC ${GLAD_DIR}/include)
+    if(TARGET OpenGL::OpenGL)
+        target_link_libraries(external-glad PUBLIC OpenGL::OpenGL)
+    elseif(TARGET OpenGL::GL)
+        target_link_libraries(external-glad PUBLIC OpenGL::GL)
+    else()
+        message(FATAL_ERROR "OpenGL not found or your CMake version is too old!")
+    endif()
+    if(TARGET OpenGL::GLX)
+        target_link_libraries(external-glad PUBLIC OpenGL::GLX)
+    endif()
+    target_link_libraries(external-glad PRIVATE ${CMAKE_DL_LIBS})
+    set_property(TARGET external-glad PROPERTY FOLDER External)
+endif()
+
+# Determine which OpenGL wrapper to use
+unset(USE_GLAD)
+unset(USE_GLEW)
+if(TARGET external-glad AND TARGET external-glew)
+    if(BUILD_PREFER_GLAD)
+        set(USE_GLAD ON)
+    else()
+        set(USE_GLEW ON)
+    endif()
+elseif(TARGET external-glad)
+    set(USE_GLAD ON)
+elseif(TARGET external-glew)
+    set(USE_GLEW ON)
 else()
     message(
         FATAL_ERROR
-            "GLEW is required - at least one of ALLOW_SYSTEM_GLEW or ALLOW_BUNDLED_GLEW must be enabled and found.")
+            "glew or glad is required - at least one of ALLOW_SYSTEM_GLEW, ALLOW_BUNDLED_GLEW, or ALLOW_BUNDLED_GLAD must be enabled and found.")
+endif()
+set(MESHLAB_USE_GLAD "${USE_GLAD}" CACHE INTERNAL "" FORCE)
+set(MESHLAB_USE_GLEW "${USE_GLEW}" CACHE INTERNAL "" FORCE)
+
+if(USE_GLAD)
+    message(STATUS "  - Using glad as OpenGL loader and extension handler")
+    add_library(external-opengl ALIAS external-glad)
+elseif(USE_GLEW)
+    message(STATUS "  - Using glew as OpenGL loader and extension handler")
+    add_library(external-opengl ALIAS external-glew)
 endif()
 
 # Eigen3 - required