ported the University CGI demo from WINDOWS + GLUT + GLEW + GLU + OpenGL 4 to LINUX WAYLAND + EGL + GLES 2 with minimal cuts

GL_STUFF/GLES_3_1_compatibility.c

@@ -0,0 +1,33 @@
+#include "GLES_3_1_compatibility.h"
+
+/* fails at link time, 
+resorting to eglGetProcAddress
+
+#define GL_GLEXT_PROTOTYPES 1
+#include <GLES2/gl2ext.h>
+*/
+
+#include <EGL/egl.h>
+
+PFNGLGENVERTEXARRAYSOESPROC glGenVertexArraysOES;
+PFNGLBINDVERTEXARRAYOESPROC glBindVertexArrayOES;
+PFNGLDRAWBUFFERSEXTPROC glDrawBuffersEXT;
+
+void glGenVertexArrays( GLuint n, GLuint *arrays_ptr) {
+	glGenVertexArraysOES( n, arrays_ptr);
+}
+
+void glBindVertexArray( GLuint array_ptr) {
+	glBindVertexArrayOES( array_ptr);
+}
+
+/* https://registry.khronos.org/OpenGL/extensions/OES/OES_framebuffer_object.txt */
+void glDrawBuffers( GLsizei n,GLenum *buffers_ptr) {
+	glDrawBuffersEXT( n, buffers_ptr);
+}
+
+void GLES_3_1_compatibility_init(){
+	glGenVertexArraysOES = (PFNGLGENVERTEXARRAYSOESPROC)eglGetProcAddress("glGenVertexArraysOES");
+	glBindVertexArrayOES = (PFNGLBINDVERTEXARRAYOESPROC)eglGetProcAddress("glBindVertexArrayOES");
+	glDrawBuffersEXT = (PFNGLDRAWBUFFERSEXTPROC)eglGetProcAddress("glDrawBuffersEXT");
+}