added glad generator and a glad runtime

tools/glad-0.1.14a0/example/c/simple.c

@@ -0,0 +1,87 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <glad/glad.h>
+#ifdef __APPLE__
+#include <GLUT/glut.h>
+#else
+#include <GL/glut.h>
+#endif
+
+// This file is a modified version of gl3w's test.c
+// https://github.com/skaslev/gl3w/blob/master/src/test.c
+
+// Compile:
+// gcc example/c/simple.c -Ibuild/include build/src/glad.c -lglut -ldl
+
+
+static int width = 600, height = 600;
+
+static void display(void)
+{
+    glClearColor(1.0f, 0.2f, 0.7f, 1.0f);
+    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+    glutSwapBuffers();
+    glutPostRedisplay();
+}
+
+static void reshape(int w, int h)
+{
+    width = w > 1 ? w : 1;
+    height = h > 1 ? h : 1;
+    glViewport(0, 0, width, height);
+    glClearDepth(1.0);
+    glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
+    glEnable(GL_DEPTH_TEST);
+}
+
+
+#ifdef GLAD_DEBUG
+void pre_gl_call(const char *name, void *funcptr, int len_args, ...) {
+    printf("Calling: %s (%d arguments)\n", name, len_args);
+}
+#endif
+
+
+int main(int argc, char **argv)
+{
+    if(gladLoadGL()) {
+        // you need an OpenGL context before loading glad
+        printf("I did load GL with no context!\n");
+        exit(-1);
+    }
+
+    glutInit(&argc, argv);
+    glutInitDisplayMode(GLUT_RGBA | GLUT_DEPTH | GLUT_DOUBLE);
+    glutInitWindowSize(width, height);
+    glutCreateWindow("cookie");
+
+    glutReshapeFunc(reshape);
+    glutDisplayFunc(display);
+
+    if(!gladLoadGL()) {
+        printf("Something went wrong!\n");
+        exit(-1);
+    }
+
+#ifdef GLAD_DEBUG
+    // before every opengl call call pre_gl_call
+    glad_set_pre_callback(pre_gl_call);
+    // don't use the callback for glClear
+    // (glClear could be replaced with your own function)
+    glad_debug_glClear = glad_glClear;
+#endif
+
+    // gladLoadGLLoader(&glutGetProcAddress);
+    printf("OpenGL %d.%d\n", GLVersion.major, GLVersion.minor);
+    if (GLVersion.major < 2) {
+        printf("Your system doesn't support OpenGL >= 2!\n");
+        return -1;
+    }
+
+    printf("OpenGL %s, GLSL %s\n", glGetString(GL_VERSION),
+           glGetString(GL_SHADING_LANGUAGE_VERSION));
+
+    glutMainLoop();
+
+    return 0;
+}