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

GL_STUFF/SOURCES/UTILS/OnlyOnce.cpp

@@ -0,0 +1,50 @@
+#include "../../HEADERS/UTILS/OnlyOnce.hpp"
+/*
+#include <GL/glew.h>
+*/
+
+
+#ifndef STB_IMAGE_IMPLEMENTATION
+#define STB_IMAGE_IMPLEMENTATION
+#endif // !STB_IMAGE_IMPLEMENTATION
+#include "../../HEADERS/UTILS/stb_image.h"
+
+GLuint loadImg(const char* path) {
+	GLuint texture;
+	int width, height, nrChannels;
+	GLenum format;
+	unsigned char* data;
+
+	glGenTextures(1, &texture);
+	glActiveTexture(GL_TEXTURE0);
+	glBindTexture(GL_TEXTURE_2D, texture);
+	//Gestione minification e magnification
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+
+	data = stbi_load(path, &width, &height, &nrChannels, 0);
+	if (data)
+	{
+
+		if (nrChannels == 3)
+			format = GL_RGB;
+
+		if (nrChannels == 4)
+			format = GL_RGBA;
+
+		glTexImage2D(GL_TEXTURE_2D, 0, format, width, height, 0, format, GL_UNSIGNED_BYTE, data);
+		glGenerateMipmap(GL_TEXTURE_2D);
+		printf("Tutto OK %d %d \n", width, height);
+	}
+	else
+	{
+		printf("LoadImage Errore nel caricare la texture\n");
+		printf("%s\n", stbi_failure_reason());
+	}
+	stbi_image_free(data);
+	glBindTexture(GL_TEXTURE_2D, 0);
+
+	return texture;
+}