Android: link to libGLESv3 when WANT_GLES3=on. Fix compile errors. Fixes #1475

Author: alemart

CMakeLists.txt

@@ -662,17 +662,28 @@ if(WANT_OPENGL)
             set(ALLEGRO_CFG_OPENGL 1)
             set(ALLEGRO_CFG_OPENGLES 1)
             set(ALLEGRO_CFG_OPENGLES2 1)
-            if(WANT_GLES3)
+            set(ALLEGRO_CFG_OPENGL_PROGRAMMABLE_PIPELINE 1)
+            set(OPENGL_LIBRARIES ${OPENGLES2_LIBRARIES})
+            set(OPENGLES_INCLUDE_DIR ${OPENGLES2_INCLUDE_DIR})
+            set(OPENGL_SUMMARY "- OpenGL: ES 2.0")
+
+            if(WANT_GLES3 AND NOT ANDROID)
                 set(SUPPORT_OPENGLES3 1)
                 set(ALLEGRO_CFG_OPENGLES3 1)
                 set(OPENGL_SUMMARY "- OpenGL: ES 3.0")
-            else(WANT_GLES3)
-                set(OPENGL_SUMMARY "- OpenGL: ES 2.0")
-            endif(WANT_GLES3)
-            set(ALLEGRO_CFG_OPENGL_PROGRAMMABLE_PIPELINE 1)
-            set(OPENGL_LIBRARIES "${OPENGLES2_LIBRARIES}")
+            elseif(WANT_GLES3 AND ANDROID)
+                find_package(OpenGLES3)
+                if(OPENGLES3_FOUND)
+                    set(SUPPORT_OPENGLES3 1)
+                    set(ALLEGRO_CFG_OPENGLES3 1)
+                    set(OPENGL_LIBRARIES ${OPENGLES3_LIBRARIES})
+                    list(APPEND OPENGLES_INCLUDE_DIR ${OPENGLES3_INCLUDE_DIR})
+                    set(OPENGL_SUMMARY "- OpenGL: ES 3.0")
+                endif(OPENGLES3_FOUND)
+            endif()
+
             if(NOT IPHONE)
-	        include_directories(SYSTEM ${OPENGLES2_INCLUDE_DIR})
+	        include_directories(SYSTEM ${OPENGLES_INCLUDE_DIR})
             endif()
         else(OPENGLES2_FOUND)
             if(GL_BUILD_TYPE MATCHES "auto")

cmake/FindOpenGLES3.cmake

@@ -0,0 +1,30 @@
+# - Find OpenGLES3
+# Find the native OpenGLES3 includes and libraries
+# (based on FindOpenGLES2.cmake)
+#
+#  OPENGLES3_INCLUDE_DIR - where to find GLES3/gl3.h, etc.
+#  OPENGLES3_LIBRARIES   - List of libraries when using OpenGLES.
+#  OPENGLES3_FOUND       - True if OpenGLES found.
+
+if(OPENGLES3_INCLUDE_DIR)
+    # Already in cache, be silent
+    set(OPENGLES3_FIND_QUIETLY TRUE)
+endif(OPENGLES3_INCLUDE_DIR)
+
+find_path(OPENGLES3_INCLUDE_DIR GLES3/gl3.h)
+
+find_library(OPENGLES3_gl_LIBRARY NAMES GLESv3)
+find_library(OPENGLES3_egl_LIBRARY NAMES EGL)
+
+# Handle the QUIETLY and REQUIRED arguments and set OPENGLES3_FOUND
+# to TRUE if all listed variables are TRUE.
+include(FindPackageHandleStandardArgs)
+set(FPHSA_NAME_MISMATCHED TRUE)
+find_package_handle_standard_args(OPENGLES3 DEFAULT_MSG
+    OPENGLES3_INCLUDE_DIR OPENGLES3_gl_LIBRARY OPENGLES3_egl_LIBRARY)
+
+set(OPENGLES3_LIBRARIES ${OPENGLES3_gl_LIBRARY} ${OPENGLES3_egl_LIBRARY})
+
+mark_as_advanced(OPENGLES3_INCLUDE_DIR)
+mark_as_advanced(OPENGLES3_gl_LIBRARY)
+mark_as_advanced(OPENGLES3_egl_LIBRARY)

include/allegro5/allegro_opengl.h

@@ -101,7 +101,12 @@
 #include <GLES3/gl3ext.h>
 
 // TODO: should defines from GLES2 be there as well?
+// Answer: according to the Khronos OpenGL ES Registry, the extension header
+// file of OpenGL ES 3.x is actually <GLES2/gl2ext.h>. Note that GLES 3.x is
+// backwards-compatible with GLES2. See https://registry.khronos.org/OpenGL/
 // TODO: Also, how does it relate to src/opengl/ogl_helpers.h ?
+// Answer: redefinition of a constant
+#include <GLES2/gl2ext.h>
 
 #define glRenderbufferStorageMultisampleEXT glRenderbufferStorageMultisample
 

src/opengl/ogl_fbo.c

@@ -22,6 +22,7 @@
 #include "allegro5/internal/aintern_pixels.h"
 
 #ifdef ALLEGRO_ANDROID
+   #include <android/api-level.h>
    #include "allegro5/internal/aintern_android.h"
 #elif defined ALLEGRO_IPHONE
    #include "allegro5/internal/aintern_iphone.h"
@@ -622,12 +623,14 @@ static void use_fbo_for_bitmap(ALLEGRO_DISPLAY *display,
                GL_TEXTURE_2D, ogl_bitmap->texture, 0);
          }
 #if ((!defined ALLEGRO_CFG_OPENGLES || defined ALLEGRO_CFG_OPENGLES3) && !defined ALLEGRO_IPHONE)
+#if (!defined ALLEGRO_ANDROID) || (__ANDROID_API__ >= 28) /* Android: glFramebufferTexture2DMultisampleEXT exists in newer libGLESv[23].so */
          else {
             glFramebufferTexture2DMultisampleEXT(GL_FRAMEBUFFER,
                GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, ogl_bitmap->texture, 
                0, al_get_bitmap_samples(bitmap));
 
          }
+#endif
 #endif
       }
       else

src/opengl/ogl_helpers.h

@@ -43,7 +43,9 @@
    IS_ANDROID_AND(al_get_display_flags(dpy) & ALLEGRO_PROGRAMMABLE_PIPELINE)
 
 #if defined ALLEGRO_CFG_OPENGLES2
+#ifndef GL_EXT_draw_buffers
    #define GL_COLOR_ATTACHMENT0_EXT     GL_COLOR_ATTACHMENT0
+#endif
    #define GL_FRAMEBUFFER_BINDING_EXT   GL_FRAMEBUFFER_BINDING
    #define GL_FRAMEBUFFER_COMPLETE_EXT  GL_FRAMEBUFFER_COMPLETE
    #define GL_FRAMEBUFFER_EXT           GL_FRAMEBUFFER