add initial GL module

src/gui/GL.cc

@@ -0,0 +1,46 @@
+#include "GL.h"
+#include "gl3w.h"
+
+/**
+ * Initialize OpenGL.
+ *
+ * @retval true OpenGL was loaded successfully.
+ * @retval false Loading OpenGL failed.
+ */
+bool GL_Init()
+{
+    static bool loaded = false;
+
+    if (loaded)
+        return true;
+
+    if (gl3wInit() != 0)
+    {
+        /* Failed to gl3wInit() */
+        return false;
+    }
+
+    if (!gl3wIsSupported(3, 0))
+    {
+        /* OpenGL 3.0 is not supported */
+        return false;
+    }
+
+    glEnable(GL_SCISSOR_TEST);
+    glActiveTexture(GL_TEXTURE0);
+    glEnable(GL_BLEND);
+    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+
+    return loaded = true;
+}
+
+/**
+ * Resize the OpenGL viewport.
+ *
+ * @param[in] width Width of the new viewport.
+ * @param[in] height Height of the new viewport.
+ */
+void GL_Resize(int width, int height)
+{
+    glViewport(0, 0, width, height);
+}

src/gui/GL.h

@@ -0,0 +1,7 @@
+#ifndef JES_GL_H
+#define JES_GL_H
+
+bool GL_Init();
+void GL_Resize(int width, int height);
+
+#endif