Make the modern GL renderer compatible with OpenGL 2.0/OpenGL ES 2.0

CMakeLists.txt

@@ -96,12 +96,6 @@ endif()
 # Platform specific files builds
 file(GLOB PLATFORM_SOURCES src/${PLATFORM}/*.c)
 
-# OpenGL ES 3.0 / WebGL2 compatibility
-option(ENABLE_GLES "Build the gl_renderer against OpenGL ES 3.0 / WebGL2 instead of desktop GL 4.1 Core" OFF)
-if (ENABLE_GLES AND ENABLE_LEGACY_GL)
-    set(ENABLE_LEGACY_GL OFF)
-endif()
-
 add_executable(butterscotch ${SOURCES} ${PLATFORM_SOURCES} ${AUDIO_SOURCES})
 target_include_directories(butterscotch PRIVATE ${CMAKE_SOURCE_DIR}/src)
 
@@ -220,14 +214,8 @@ if(PLATFORM STREQUAL "desktop")
     endif()
 
     # GLAD
-    if(ENABLE_GLES)
-        add_compile_definitions(ENABLE_GLES)
-        add_library(glad STATIC vendor/glad-gles/src/glad.c)
-        target_include_directories(glad PUBLIC vendor/glad-gles/include)
-    else()
-        add_library(glad STATIC vendor/glad/src/glad.c)
-        target_include_directories(glad PUBLIC vendor/glad/include)
-    endif()
+    add_library(glad STATIC vendor/glad/src/glad.c)
+    target_include_directories(glad PUBLIC vendor/glad/include)
 
     # stb_image
     target_include_directories(butterscotch PUBLIC vendor/stb/image)
@@ -318,7 +306,6 @@ elseif(PLATFORM STREQUAL "web")
     target_include_directories(butterscotch PRIVATE ${CMAKE_SOURCE_DIR}/src/gl)
     target_include_directories(butterscotch PRIVATE ${CMAKE_SOURCE_DIR}/src/gl_common)
     target_include_directories(butterscotch PRIVATE ${CMAKE_SOURCE_DIR}/src/image)
-    add_compile_definitions(ENABLE_GLES)
 
     # stb_image
     target_include_directories(butterscotch PUBLIC vendor/stb/image)

Makefile

@@ -96,13 +96,11 @@ ENABLE_GLAD := 1
 endif
 
 ifndef DISABLE_LEGACY_GL
-ifndef ENABLE_GLES
 DEFINES += -DENABLE_LEGACY_GL
 SRCS += $(wildcard src/gl_legacy/*.c)
 INCLUDES += -Isrc/gl_legacy
 HEADERS += $(wildcard src/gl_legacy/*.h) $(wildcard src/gl/*.h)
 endif
-endif
 
 ifndef DISABLE_MODERN_GL
 DEFINES += -DENABLE_MODERN_GL
@@ -124,10 +122,6 @@ $(error must enable at least 1 renderer)
 endif
 endif
 
-ifdef ENABLE_GLES
-DEFINES += -DENABLE_GLES
-endif
-
 ifeq ($(AUDIO_BACKEND),miniaudio)
 INCLUDES += -Isrc/audio/miniaudio -Ivendor/miniaudio
 DEFINES += -DUSE_MINIAUDIO
@@ -150,14 +144,9 @@ endif
 endif
 
 ifdef ENABLE_GLAD
-ifdef ENABLE_GLES
-SRCS += vendor/glad-gles/src/glad.c
-INCLUDES += -Ivendor/glad-gles/include
-else
 SRCS += vendor/glad/src/glad.c
 INCLUDES += -Ivendor/glad/include
 endif
-endif
 
 ifeq ($(OS),Windows)
 LIBS += -static -lwinmm

src/desktop/backends/glfw2.c

@@ -18,6 +18,43 @@
 
 static Runner *g_runner;
 
+static bool tryOpenWindow(int reqW, int reqH) {
+#ifdef GLFW_OPENGL_VERSION_MAJOR
+    if (gfx == SOFTWARE || gfx == LEGACY_GL) {
+        glfwOpenWindowHint(GLFW_OPENGL_VERSION_MAJOR, 1);
+        glfwOpenWindowHint(GLFW_OPENGL_VERSION_MINOR, (gfx == SOFTWARE) ? 0 : 1);
+        return glfwOpenWindow(reqW, reqH, 8, 8, 8, 8, 24, 8, GLFW_WINDOW) != 0;
+    }
+
+    for (size_t i = 0; i < sizeof(GLCommon_versions)/sizeof(GLCommon_versions[0]); i++) {
+        glfwOpenWindowHint(GLFW_OPENGL_VERSION_MAJOR, GLCommon_versions[i].major);
+        glfwOpenWindowHint(GLFW_OPENGL_VERSION_MINOR, GLCommon_versions[i].minor);
+
+        if (GLCommon_versions[i].major >= 3) {
+            if (GLCommon_versions[i].major == 3 && GLCommon_versions[i].minor == 2) {
+                glfwOpenWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
+            } else {
+                glfwOpenWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_FALSE);
+            }
+        } else {
+            glfwOpenWindowHint(GLFW_OPENGL_PROFILE, 0);
+        }
+
+#ifndef NDEBUG
+        glfwOpenWindowHint(GLFW_OPENGL_DEBUG_CONTEXT, GL_TRUE);
+#endif
+        if (glfwOpenWindow(reqW, reqH, 8, 8, 8, 8, 24, 8, GLFW_WINDOW) != 0) {
+            return true;
+        }
+        glfwCloseWindow();
+    }
+
+    return false;
+#else
+    return glfwOpenWindow(reqW, reqH, 8, 8, 8, 8, 24, 8, GLFW_WINDOW) != 0;
+#endif
+}
+
 void platformSetWindowTitle(const char* title) {
     char windowTitle[256];
     snprintf(windowTitle, sizeof(windowTitle), "Butterscotch - %s", title);
@@ -152,52 +189,13 @@ bool platformInit(int32_t reqW, int32_t reqH, const char *title, bool headless)
         return false;
     }
 
-#ifdef GLFW_OPENGL_VERSION_MAJOR
-    if (gfx == SOFTWARE) {
-        glfwOpenWindowHint(GLFW_OPENGL_VERSION_MAJOR, 1);
-        glfwOpenWindowHint(GLFW_OPENGL_VERSION_MINOR, 0);
-    } else if (gfx == LEGACY_GL) {
-        glfwOpenWindowHint(GLFW_OPENGL_VERSION_MAJOR, 1);
-        glfwOpenWindowHint(GLFW_OPENGL_VERSION_MINOR, 1);
-    } else {
-#ifdef ENABLE_GLES
-        glfwOpenWindowHint(GLFW_CLIENT_API, GLFW_OPENGL_ES_API);
-        glfwOpenWindowHint(GLFW_OPENGL_VERSION_MAJOR, 3);
-        glfwOpenWindowHint(GLFW_OPENGL_VERSION_MINOR, 0);
-#else
-        glfwOpenWindowHint(GLFW_OPENGL_VERSION_MAJOR, 3);
-        glfwOpenWindowHint(GLFW_OPENGL_VERSION_MINOR, 2);
-        glfwOpenWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
-        glfwOpenWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
-        glfwOpenWindowHint(GLFW_OPENGL_DEBUG_CONTEXT, GL_TRUE);
-#endif
-    }
-#endif
-
     // Init GLFW
     if (!glfwInit()) {
         fprintf(stderr, "Failed to initialize GLFW\n");
         return false;
     }
 
-#ifdef GLFW_OPENGL_VERSION_MAJOR
-    if (gfx == SOFTWARE) {
-        glfwOpenWindowHint(GLFW_OPENGL_VERSION_MAJOR, 1);
-        glfwOpenWindowHint(GLFW_OPENGL_VERSION_MINOR, 0);
-    } else if (gfx == LEGACY_GL) {
-        glfwOpenWindowHint(GLFW_OPENGL_VERSION_MAJOR, 1);
-        glfwOpenWindowHint(GLFW_OPENGL_VERSION_MINOR, 1);
-    } else {
-        glfwOpenWindowHint(GLFW_OPENGL_VERSION_MAJOR, 3);
-        glfwOpenWindowHint(GLFW_OPENGL_VERSION_MINOR, 2);
-        glfwOpenWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
-        glfwOpenWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
-        glfwOpenWindowHint(GLFW_OPENGL_DEBUG_CONTEXT, GL_TRUE);
-    }
-#endif
-
-    int window = glfwOpenWindow(reqW, reqH, 8, 8, 8, 8, 24, 8, GLFW_WINDOW);
-    if (!window) {
+    if (!tryOpenWindow(reqW, reqH)) {
         fprintf(stderr, "Failed to create GLFW window\n");
         glfwTerminate();
         return false;

src/desktop/backends/glfw3.c

@@ -28,6 +28,56 @@ static void framebufferToLogical(float xs, float ys, int fbW, int fbH, int* outW
     *outH = (ys > 0.0f) ? (int) ceilf((float) fbH / ys) : fbH;
 }
 
+static GLFWwindow *tryOpenWindow(int reqW, int reqH, const char* title) {
+    if (gfx == SOFTWARE || gfx == LEGACY_GL) {
+        glfwDefaultWindowHints();
+        glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 1);
+        glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, (gfx == SOFTWARE) ? 0 : 1);
+
+#ifndef NDEBUG
+        glfwWindowHint(GLFW_OPENGL_DEBUG_CONTEXT, GL_TRUE);
+#endif
+
+        return glfwCreateWindow(reqW, reqH, title, NULL, NULL);
+    }
+
+    for (size_t i = 0; i < sizeof(GLCommon_versions)/sizeof(GLCommon_versions[0]); i++) {
+        GLFWwindow *window;
+
+        glfwDefaultWindowHints();
+
+#ifndef NDEBUG
+        glfwWindowHint(GLFW_OPENGL_DEBUG_CONTEXT, GL_TRUE);
+#endif
+
+        glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, GLCommon_versions[i].major);
+        glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, GLCommon_versions[i].minor);
+
+        if (GLCommon_versions[i].gles) {
+            glfwWindowHint(GLFW_CLIENT_API, GLFW_OPENGL_ES_API);
+        } else {
+            glfwWindowHint(GLFW_CLIENT_API, GLFW_OPENGL_API);
+            if (GLCommon_versions[i].major >= 3) {
+                if (GLCommon_versions[i].major == 3 && GLCommon_versions[i].minor == 2) {
+                    glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
+                } else {
+                    glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_FALSE);
+                }
+            } else {
+                glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_ANY_PROFILE);
+            }
+        }
+
+        window = glfwCreateWindow(reqW, reqH, title, NULL, NULL);
+        if (window) {
+            return window;
+        }
+
+    }
+
+    return NULL;
+}
+
 void platformSetWindowTitle(const char* title) {
     char windowTitle[256];
     snprintf(windowTitle, sizeof(windowTitle), "Butterscotch - %s", title);
@@ -177,26 +227,6 @@ bool platformInit(int32_t reqW, int32_t reqH, const char *title, bool headless)
         return false;
     }
 
-    if (gfx == SOFTWARE) {
-        glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 1);
-        glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 0);
-    } else if (gfx == LEGACY_GL) {
-        glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 1);
-        glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 1);
-    } else {
-#ifdef ENABLE_GLES
-        glfwWindowHint(GLFW_CLIENT_API, GLFW_OPENGL_ES_API);
-        glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
-        glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 0);
-#else
-        glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
-        glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 2);
-        glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
-        glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
-        glfwWindowHint(GLFW_OPENGL_DEBUG_CONTEXT, GL_TRUE);
-#endif
-    }
-
     // init gamepad mappings
     const char* dbPath = "gamecontrollerdb.txt";
     FILE* f = fopen(dbPath, "r");
@@ -224,7 +254,7 @@ bool platformInit(int32_t reqW, int32_t reqH, const char *title, bool headless)
     if (headless)
         glfwWindowHint(GLFW_VISIBLE, GLFW_FALSE);
 
-    window = glfwCreateWindow(reqW, reqH, title, nullptr, nullptr);
+    window = tryOpenWindow(reqW, reqH, title);
     if (!window) {
         fprintf(stderr, "Failed to create GLFW window\n");
         glfwTerminate();