add GLUT_window ex

GLUT_window/image_functions.h

@@ -0,0 +1,47 @@
+/*
+ * This file is part of the opengl project.
+ * Copyright 2020 Edward V. Emelianov <edward.emelianoff@gmail.com>.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+#ifndef IMAGE_FUNCTIONS__
+#define IMAGE_FUNCTIONS__
+
+#include <GL/glut.h>
+#include "imageview.h"
+
+// functions for converting grayscale value into colour
+typedef enum{
+    COLORFN_LINEAR, // linear
+    COLORFN_LOG,    // ln
+    COLORFN_SQRT,   // sqrt
+    COLORFN_MAX     // end of list
+} colorfn_type;
+
+typedef struct{
+    uint16_t *data;
+    int w;
+    int h;
+} IMG;
+
+void change_displayed_image(windowData *win, IMG *convertedImage);
+
+void gray2rgb(double gray, GLubyte *rgb);
+colorfn_type get_colorfun();
+void change_colorfun(colorfn_type f);
+void roll_colorfun();
+
+#endif // IMAGE_FUNCTIONS__