ref: 4cbc56e272c4e90348cdfd7ab88edf243d881df1
parent: 0352af333bbf52f59cde973dfe489b8f57b98eef
author: Clownacy <[email protected]>
date: Mon Jan 20 08:13:56 EST 2020
Add OpenGL ES 2.0 renderer
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -14,7 +14,7 @@
option(JAPANESE "Enable the Japanese-language build (instead of the unofficial Aeon Genesis English translation)" OFF)
option(FIX_BUGS "Fix various bugs in the game" OFF)
option(DEBUG_SAVE "Re-enable the ability to drag-and-drop save files onto the window" OFF)
-set(RENDERER "SDLTexture" CACHE STRING "Which renderer the game should use: 'OpenGL3' for an OpenGL 3.2 renderer, 'SDLTexture' for SDL2's hardware-accelerated Texture API, 'SDLSurface' for SDL2's software-rendered Surface API, or 'Software' for a handwritten software renderer")
+set(RENDERER "SDLTexture" CACHE STRING "Which renderer the game should use: 'OpenGL3' for an OpenGL 3.2 renderer, 'OpenGLES2' for an OpenGL ES 2.0 renderer, 'SDLTexture' for SDL2's hardware-accelerated Texture API, 'SDLSurface' for SDL2's software-rendered Surface API, or 'Software' for a handwritten software renderer")
option(WARNINGS "Enable common compiler warnings (for GCC-compatible compilers and MSVC only)" OFF)
option(WARNINGS_ALL "Enable ALL compiler warnings (for Clang and MSVC only)" OFF)
@@ -337,6 +337,8 @@
if(RENDERER MATCHES "OpenGL3")
target_sources(CSE2 PRIVATE "src/Backends/Rendering/OpenGL3.cpp")
+elseif(RENDERER MATCHES "OpenGLES2")
+ target_sources(CSE2 PRIVATE "src/Backends/Rendering/OpenGLES2.cpp")
elseif(RENDERER MATCHES "SDLTexture")
target_sources(CSE2 PRIVATE "src/Backends/Rendering/SDLTexture.cpp")
elseif(RENDERER MATCHES "SDLSurface")
@@ -502,6 +504,12 @@
find_package(OpenGL REQUIRED)
target_link_libraries(CSE2 OpenGL::GL)
+endif()
+
+if(RENDERER MATCHES "OpenGLES2")
+ find_package(OpenGLES2 REQUIRED)
+ target_include_directories(CSE2 PRIVATE ${OPENGLES2_INCLUDE_DIR})+ target_link_libraries(CSE2 ${OPENGLES2_LIBRARIES})endif()
##
--- a/Makefile
+++ b/Makefile
@@ -243,6 +243,11 @@
else
CSE2_LIBS += -lGL -ldl
endif
+else ifeq ($(RENDERER), OpenGLES2)
+ SOURCES += src/Backends/Rendering/OpenGLES2.cpp
+ CSE2_CFLAGS += $(shell $(PKGCONFIG) --cflags glesv2)
+ CSE2_CXXFLAGS += $(shell $(PKGCONFIG) --cflags glesv2)
+ CSE2_LIBS += $(shell $(PKGCONFIG) --libs glesv2)
else ifeq ($(RENDERER), SDLTexture)
SOURCES += src/Backends/Rendering/SDLTexture.cpp
else ifeq ($(RENDERER), SDLSurface)
--- a/README.md
+++ b/README.md
@@ -64,6 +64,7 @@
`-DFIX_BUGS=ON` | Fix various bugs in the game
`-DDEBUG_SAVE=ON` | Re-enable the ability to drag-and-drop save files onto the window
`-DRENDERER=OpenGL3` | Use the hardware-accelerated OpenGL 3.2 renderer
+`-DRENDERER=OpenGLES2` | Use the hardware-accelerated OpenGL ES 2.0 renderer
`-DRENDERER=SDLTexture` | Use the hardware-accelerated SDL2 Texture API renderer (default)
`-DRENDERER=SDLSurface` | Use the software-rendered SDL2 Surface API renderer
`-DRENDERER=Software` | Use the handwritten software renderer
@@ -97,6 +98,7 @@
`WINDOWS=1` | Build for Windows
`DEBUG_SAVE=1` | Re-enable the ability to drag-and-drop save files onto the window
`RENDERER=OpenGL3` | Use the hardware-accelerated OpenGL 3.2 renderer
+`RENDERER=OpenGLES2` | Use the hardware-accelerated OpenGL ES 2.0 renderer
`RENDERER=SDLTexture` | Use the hardware-accelerated SDL2 Texture API renderer (default)
`RENDERER=SDLSurface` | Use the software-rendered SDL2 Surface API renderer
`RENDERER=Software` | Use the hand-written software renderer
--- /dev/null
+++ b/cmake/FindOpenGLES2.cmake
@@ -1,0 +1,120 @@
+#-------------------------------------------------------------------
+# This file is stolen from part of the CMake build system for OGRE (Object-oriented Graphics Rendering Engine) http://www.ogre3d.org/
+#
+# The contents of this file are placed in the public domain. Feel
+# free to make use of it in any way you like.
+#-------------------------------------------------------------------
+
+# - Try to find OpenGLES and EGL
+# Once done this will define
+#
+# OPENGLES2_FOUND - system has OpenGLES
+# OPENGLES2_INCLUDE_DIR - the GL include directory
+# OPENGLES2_LIBRARIES - Link these to use OpenGLES
+#
+# EGL_FOUND - system has EGL
+# EGL_INCLUDE_DIR - the EGL include directory
+# EGL_LIBRARIES - Link these to use EGL
+
+# Win32, Apple, and Android are not tested!
+# Linux tested and works
+
+if(WIN32)
+ if(CYGWIN)
+ find_path(OPENGLES2_INCLUDE_DIR GLES2/gl2.h)
+ find_library(OPENGLES2_LIBRARY libGLESv2)
+ else()
+ if(BORLAND)
+ set(OPENGLES2_LIBRARY import32 CACHE STRING "OpenGL ES 2.x library for Win32")
+ else()
+ # TODO
+ # set(OPENGLES_LIBRARY ${SOURCE_DIR}/Dependencies/lib/release/libGLESv2.lib CACHE STRING "OpenGL ES 2.x library for win32"+ endif()
+ endif()
+elseif(APPLE)
+ create_search_paths(/Developer/Platforms)
+ findpkg_framework(OpenGLES2)
+ set(OPENGLES2_LIBRARY "-framework OpenGLES")
+else()
+ find_path(OPENGLES2_INCLUDE_DIR GLES2/gl2.h
+ PATHS /usr/openwin/share/include
+ /opt/graphics/OpenGL/include
+ /opt/vc/include
+ /usr/X11R6/include
+ /usr/include
+ )
+
+ find_library(OPENGLES2_LIBRARY
+ NAMES GLESv2
+ PATHS /opt/graphics/OpenGL/lib
+ /usr/openwin/lib
+ /usr/shlib /usr/X11R6/lib
+ /opt/vc/lib
+ /usr/lib/aarch64-linux-gnu
+ /usr/lib/arm-linux-gnueabihf
+ /usr/lib
+ )
+
+ if(NOT BUILD_ANDROID)
+ find_path(EGL_INCLUDE_DIR EGL/egl.h
+ PATHS /usr/openwin/share/include
+ /opt/graphics/OpenGL/include
+ /opt/vc/include
+ /usr/X11R6/include
+ /usr/include
+ )
+
+ find_library(EGL_LIBRARY
+ NAMES EGL
+ PATHS /opt/graphics/OpenGL/lib
+ /usr/openwin/lib
+ /usr/shlib
+ /usr/X11R6/lib
+ /opt/vc/lib
+ /usr/lib/aarch64-linux-gnu
+ /usr/lib/arm-linux-gnueabihf
+ /usr/lib
+ )
+
+ # On Unix OpenGL usually requires X11.
+ # It doesn't require X11 on OSX.
+
+ if(OPENGLES2_LIBRARY)
+ if(NOT X11_FOUND)
+ include(FindX11)
+ endif()
+ if(X11_FOUND)
+ set(OPENGLES2_LIBRARIES ${X11_LIBRARIES})+ endif()
+ endif()
+ endif()
+endif()
+
+set(OPENGLES2_LIBRARIES ${OPENGLES2_LIBRARIES} ${OPENGLES2_LIBRARY})+
+if(BUILD_ANDROID)
+ if(OPENGLES2_LIBRARY)
+ set(EGL_LIBRARIES)
+ set(OPENGLES2_FOUND TRUE)
+ endif()
+else()
+ if(OPENGLES2_LIBRARY AND EGL_LIBRARY)
+ set(OPENGLES2_LIBRARIES ${OPENGLES2_LIBRARY} ${OPENGLES2_LIBRARIES})+ set(EGL_LIBRARIES ${EGL_LIBRARY} ${EGL_LIBRARIES})+ set(OPENGLES2_FOUND TRUE)
+ endif()
+endif()
+
+mark_as_advanced(
+ OPENGLES2_INCLUDE_DIR
+ OPENGLES2_LIBRARY
+ EGL_INCLUDE_DIR
+ EGL_LIBRARY
+)
+
+if(OPENGLES2_FOUND)
+ message(STATUS "Found system OpenGL ES 2 library: ${OPENGLES2_LIBRARIES}")+else()
+ set(OPENGLES2_LIBRARIES "")
+endif()
+
--- a/src/Backends/Rendering/OpenGL3.cpp
+++ b/src/Backends/Rendering/OpenGL3.cpp
@@ -1,3 +1,5 @@
+// Dual OpenGL 3.2 and OpenGL ES 2.0 renderer
+
#include "../Rendering.h"
#include <stddef.h>
@@ -5,7 +7,12 @@
#include <stdlib.h>
#include <string.h>
+#ifdef USE_OPENGLES2
+#include <GLES2/gl2.h>
+#else
#include <glad/glad.h>
+#endif
+
#include "SDL.h"
#include "../../WindowsWrapper.h"
@@ -67,7 +74,9 @@
static GLint program_glyph_normal_uniform_colour;
static GLint program_glyph_subpixel_part2_uniform_colour;
+#ifndef USE_OPENGLES2
static GLuint vertex_array_id;
+#endif
static GLuint vertex_buffer_id;
static GLuint framebuffer_id;
@@ -78,7 +87,101 @@
static Backend_Surface framebuffer;
+#ifdef USE_OPENGLES2
static const GLchar *vertex_shader_plain = " \
+#version 100\n \
+attribute vec2 input_vertex_coordinates; \
+void main() \
+{ \+ gl_Position = vec4(input_vertex_coordinates.x, input_vertex_coordinates.y, 0.0, 1.0); \
+} \
+";
+
+static const GLchar *vertex_shader_texture = " \
+#version 100\n \
+attribute vec2 input_vertex_coordinates; \
+attribute vec2 input_texture_coordinates; \
+varying vec2 texture_coordinates; \
+void main() \
+{ \+ texture_coordinates = input_texture_coordinates; \
+ gl_Position = vec4(input_vertex_coordinates.x, input_vertex_coordinates.y, 0.0, 1.0); \
+} \
+";
+
+static const GLchar *fragment_shader_texture = " \
+#version 100\n \
+precision mediump float; \
+uniform sampler2D tex; \
+varying vec2 texture_coordinates; \
+void main() \
+{ \+ gl_FragColor = texture2D(tex, texture_coordinates); \
+} \
+";
+
+static const GLchar *fragment_shader_texture_colour_key = " \
+#version 100\n \
+precision mediump float; \
+uniform sampler2D tex; \
+varying vec2 texture_coordinates; \
+void main() \
+{ \+ vec4 colour = texture2D(tex, texture_coordinates); \
+\
+ if (colour.xyz == vec3(0.0f, 0.0f, 0.0f)) \
+ discard; \
+\
+ gl_FragColor = colour; \
+} \
+";
+
+static const GLchar *fragment_shader_colour_fill = " \
+#version 100\n \
+precision mediump float; \
+uniform vec4 colour; \
+void main() \
+{ \+ gl_FragColor = colour; \
+} \
+";
+
+static const GLchar *fragment_shader_glyph_normal = " \
+#version 100\n \
+precision mediump float; \
+uniform sampler2D tex; \
+uniform vec4 colour; \
+varying vec2 texture_coordinates; \
+void main() \
+{ \+ gl_FragColor = colour * vec4(1.0, 1.0, 1.0, texture2D(tex, texture_coordinates).r); \
+} \
+";
+
+static const GLchar *fragment_shader_glyph_subpixel_part1 = " \
+#version 100\n \
+precision mediump float; \
+uniform sampler2D tex; \
+varying vec2 texture_coordinates; \
+void main() \
+{ \+ gl_FragColor = texture2D(tex, texture_coordinates); \
+} \
+";
+
+static const GLchar *fragment_shader_glyph_subpixel_part2 = " \
+#version 100\n \
+precision mediump float; \
+uniform sampler2D tex; \
+uniform vec4 colour; \
+varying vec2 texture_coordinates; \
+void main() \
+{ \+ gl_FragColor = colour * texture2D(tex, texture_coordinates); \
+} \
+";
+#else
+static const GLchar *vertex_shader_plain = " \
#version 150 core\n \
in vec2 input_vertex_coordinates; \
void main() \
@@ -170,6 +273,7 @@
fragment = colour * texture(tex, texture_coordinates); \
} \
";
+#endif
/*
static void GLAPIENTRY MessageCallback(GLenum source, GLenum type, GLuint id, GLenum severity, GLsizei length, const GLchar *message, const void* userParam)
{@@ -195,7 +299,12 @@
glGetShaderiv(vertex_shader, GL_COMPILE_STATUS, &shader_status);
if (shader_status != GL_TRUE)
+ {+ char buffer[0x200];
+ glGetShaderInfoLog(vertex_shader, sizeof(buffer), NULL, buffer);
+ printf("Vertex shader: %s", buffer);return 0;
+ }
glAttachShader(program_id, vertex_shader);
@@ -205,7 +314,12 @@
glGetShaderiv(fragment_shader, GL_COMPILE_STATUS, &shader_status);
if (shader_status != GL_TRUE)
+ {+ char buffer[0x200];
+ glGetShaderInfoLog(fragment_shader, sizeof(buffer), NULL, buffer);
+ printf("Fragment shader: %s", buffer);return 0;
+ }
glAttachShader(program_id, fragment_shader);
@@ -216,7 +330,12 @@
glGetProgramiv(program_id, GL_LINK_STATUS, &shader_status);
if (shader_status != GL_TRUE)
+ {+ char buffer[0x200];
+ glGetProgramInfoLog(program_id, sizeof(buffer), NULL, buffer);
+ printf("Shader linker: %s", buffer);return 0;
+ }
return program_id;
}
@@ -271,10 +390,17 @@
SDL_Window* Backend_CreateWindow(const char *title, int width, int height)
{+#ifdef USE_OPENGLES2
+ SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_ES);
+ SDL_GL_SetAttribute(SDL_GL_CONTEXT_FLAGS, 0);
+ SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 2);
+ SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 0);
+#else
SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_FLAGS, SDL_GL_CONTEXT_FORWARD_COMPATIBLE_FLAG);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 2);
+#endif
return SDL_CreateWindow(title, SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, width, height, SDL_WINDOW_OPENGL);
}
@@ -292,11 +418,22 @@
{if (SDL_GL_MakeCurrent(window, context) == 0)
{+ #ifndef USE_OPENGLES2
if (gladLoadGLLoader((GLADloadproc)SDL_GL_GetProcAddress))
+ #endif
{+ #ifndef USE_OPENGLES2
// Check if the platform supports OpenGL 3.2
if (GLAD_GL_VERSION_3_2)
+ #endif
{+ #ifndef NDEBUG
+ printf("GL_VENDOR = %s\n", glGetString(GL_VENDOR));+ printf("GL_RENDERER = %s\n", glGetString(GL_RENDERER));+ printf("GL_VERSION = %s\n", glGetString(GL_VERSION));+ printf("GL_SHADING_LANGUAGE_VERSION = %s\n", glGetString(GL_SHADING_LANGUAGE_VERSION));+ #endif
+
//glEnable(GL_DEBUG_OUTPUT);
//glDebugMessageCallback(MessageCallback, 0);
@@ -303,9 +440,11 @@
glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT);
+ #ifndef USE_OPENGLES2
// Set up Vertex Array Object
glGenVertexArrays(1, &vertex_array_id);
glBindVertexArray(vertex_array_id);
+ #endif
// Set up Vertex Buffer Object
glGenBuffers(1, &vertex_buffer_id);
@@ -343,12 +482,18 @@
// Set up framebuffer screen texture (used for screen-to-surface blitting)
glGenTextures(1, &framebuffer.texture_id);
glBindTexture(GL_TEXTURE_2D, framebuffer.texture_id);
+ #ifdef USE_OPENGLES2
+ glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, window_width, window_height, 0, GL_RGB, GL_UNSIGNED_BYTE, NULL);
+ #else
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB8, window_width, window_height, 0, GL_RGB, GL_UNSIGNED_BYTE, NULL);
+ #endif
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+ #ifndef USE_OPENGLES2
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
+ #endif
framebuffer.width = window_width;
framebuffer.height = window_height;
@@ -378,7 +523,9 @@
glDeleteProgram(program_texture);
glDeleteBuffers(1, &vertex_buffer_id);
+ #ifndef USE_OPENGLES2
glDeleteVertexArrays(1, &vertex_array_id);
+ #endif
}
}
}
@@ -400,7 +547,9 @@
glDeleteProgram(program_texture_colour_key);
glDeleteProgram(program_texture);
glDeleteBuffers(1, &vertex_buffer_id);
+#ifndef USE_OPENGLES2
glDeleteVertexArrays(1, &vertex_array_id);
+#endif
SDL_GL_DeleteContext(context);
}
@@ -475,12 +624,18 @@
glGenTextures(1, &surface->texture_id);
glBindTexture(GL_TEXTURE_2D, surface->texture_id);
+#ifdef USE_OPENGLES2
+ glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, NULL);
+#else
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB8, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, NULL);
+#endif
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+#ifndef USE_OPENGLES2
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
+#endif
surface->width = width;
surface->height = height;
@@ -684,7 +839,11 @@
if (glyph == NULL)
return NULL;
+#ifdef USE_OPENGLES2
+ const unsigned int destination_pitch = ((width * 3) + 3) & ~3; // Round up to the nearest 4 (OpenGL needs this)
+#else
const unsigned int destination_pitch = (width + 3) & ~3; // Round up to the nearest 4 (OpenGL needs this)
+#endif
unsigned char *buffer = (unsigned char*)malloc(destination_pitch * height);
@@ -691,12 +850,31 @@
switch (pixel_mode)
{case FONT_PIXEL_MODE_LCD:
+ for (unsigned int y = 0; y < height; ++y)
+ {+ const unsigned char *source_pointer = pixels + y * pitch;
+ unsigned char *destination_pointer = buffer + y * destination_pitch;
+ memcpy(destination_pointer, source_pointer, width);
+ }
+
+ break;
+
case FONT_PIXEL_MODE_GRAY:
for (unsigned int y = 0; y < height; ++y)
{const unsigned char *source_pointer = pixels + y * pitch;
unsigned char *destination_pointer = buffer + y * destination_pitch;
+
+ #ifdef USE_OPENGLES2
+ for (unsigned int x = 0; x < width; ++x)
+ {+ *destination_pointer++ = *source_pointer++;
+ *destination_pointer++ = 0;
+ *destination_pointer++ = 0;
+ }
+ #else
memcpy(destination_pointer, source_pointer, width);
+ #endif
}
break;
@@ -708,7 +886,13 @@
unsigned char *destination_pointer = buffer + y * destination_pitch;
for (unsigned int x = 0; x < width; ++x)
+ {*destination_pointer++ = (*source_pointer++ ? 0xFF : 0);
+ #ifdef USE_OPENGLES2
+ *destination_pointer++ = 0;
+ *destination_pointer++ = 0;
+ #endif
+ }
}
break;
@@ -719,15 +903,25 @@
glGenTextures(1, &glyph->texture_id);
glBindTexture(GL_TEXTURE_2D, glyph->texture_id);
+#ifdef USE_OPENGLES2
if (pixel_mode == FONT_PIXEL_MODE_LCD)
+ glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width / 3, height, 0, GL_RGB, GL_UNSIGNED_BYTE, buffer);
+ else
+ glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, buffer); // OpenGL ES 2.0 doesn't support GL_RED
+ glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, buffer);
+#else
+ if (pixel_mode == FONT_PIXEL_MODE_LCD)
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB8, width / 3, height, 0, GL_RGB, GL_UNSIGNED_BYTE, buffer);
else
glTexImage2D(GL_TEXTURE_2D, 0, GL_R8, width, height, 0, GL_RED, GL_UNSIGNED_BYTE, buffer);
+#endif
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+#ifndef USE_OPENGLES2
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
+#endif
glyph->width = (pixel_mode == FONT_PIXEL_MODE_LCD ? width / 3 : width);
glyph->height = height;
--- /dev/null
+++ b/src/Backends/Rendering/OpenGLES2.cpp
@@ -1,0 +1,4 @@
+// I would use -DUSE_OPENGLES2 when RENDERER=OpenGLES2 is passed instead, but CMake likes to rebuild the entire
+// project if I do that, and Make doesn't bother rebuilding anything at all. This method avoid both of those problems.
+#define USE_OPENGLES2
+#include "OpenGL3.cpp"