Merge remote-tracking branch 'oreilly/master' into learning15

examples 15-02 changed, added 15-03

README.md

@@ -5,7 +5,7 @@ This is the example code that accompanies Learning OpenCV 3 by Adrian Kaehler an
 
 **In progress May 24, 2017**
 
-This code is in progress, currently at Chapter 15, bear with us, the code is coming, both Authors are busy, as always, building startups.
+This code is in progress, currently at Chapter 15, bear with us, the code is coming, both Authors are busy, as always, building startups. If you want to help, request to join the project. Keep pull requests to one function at a time. It doesn't have to be just examples from the book, it can be other code snippets from the book, exercises, new functionality or even a "how to use" opencv_contrib functions.
 
 Note, for your interest, included here is a _Docker_ file that
 * Loads Ubuntu 16.04 

example_09-04.cpp

@@ -1,38 +1,94 @@
 //Example 9-4. Slightly modified code from the OpenCV documentation that draws a
 //cube every frame; this modified version uses the global variables rotx and roty that are
 //connected to the sliders in Figure 9-6
+// Note: This example needs OpenGL installed on your system. It doesn't build if 
+//       the OpenGL libraries cannot be found.
+#include <GL/gl.h>
+#include <GL/glu.h>
 
 #include <opencv2/opencv.hpp>
-#include <GL/gl.h>
-#include <GL/glut.h>
+#include <opencv2/core/opengl.hpp>
+#include <iostream>
 
 using namespace std;
 
-void on_opengl( void* param ) {
-  glMatrixModel( GL_MODELVIEW );
-  glLoadIdentity();
-  glTranslated( 0.0, 0.0, -1.0 );
-  glRotatef( rotx, 1, 0, 0 );
-  glRotatef( roty, 0, 1, 0 );
-  glRotatef( 0, 0, 0, 1 );
-  static const int coords[6][4][3] = {
-    { { +1, -1, -1 }, { -1, -1, -1 }, { -1, +1, -1 }, { +1, +1, -1 } },
-    { { +1, +1, -1 }, { -1, +1, -1 }, { -1, +1, +1 }, { +1, +1, +1 } },
-    { { +1, -1, +1 }, { +1, -1, -1 }, { +1, +1, -1 }, { +1, +1, +1 } },
-    { { -1, -1, -1 }, { -1, -1, +1 }, { -1, +1, +1 }, { -1, +1, -1 } },
-    { { +1, -1, +1 }, { -1, -1, +1 }, { -1, -1, -1 }, { +1, -1, -1 } },
-    { { -1, -1, +1 }, { +1, -1, +1 }, { +1, +1, +1 }, { -1, +1, +1 } }
-  };
-  for (int i = 0; i < 6; ++i) {
-    glColor3ub( i*20, 100+i*10, i*42 );
-    glBegin(GL_QUADS);
-    for (int j = 0; j < 4; ++j) {
-      glVertex3d(
-        0.2 * coords[i][j][0],
-        0.2 * coords[i][j][1],
-        0.2 * coords[i][j][2]
-      );
+int rotx = 55, roty = 40;
+
+void on_opengl(void* param) {
+    cv::ogl::Texture2D* backgroundTex = (cv::ogl::Texture2D*)param;
+    glEnable( GL_TEXTURE_2D );
+    backgroundTex->bind();
+    cv::ogl::render(*backgroundTex);
+    glDisable( GL_TEXTURE_2D );
+
+    glMatrixMode( GL_PROJECTION );
+    glLoadIdentity();
+    glMatrixMode( GL_MODELVIEW );
+    glLoadIdentity();
+    glTranslatef(0, 0, -0.5);
+    glRotatef( rotx, 1, 0, 0 );
+    glRotatef( roty, 0, 1, 0 );
+    glRotatef( 0, 0, 0, 1 );
+    glEnable( GL_DEPTH_TEST );
+    glDepthFunc( GL_LESS );
+    static const int coords[6][4][3] = {
+        { { +1, -1, -1 }, { -1, -1, -1 }, { -1, +1, -1 }, { +1, +1, -1 } },
+        { { +1, +1, -1 }, { -1, +1, -1 }, { -1, +1, +1 }, { +1, +1, +1 } },
+        { { +1, -1, +1 }, { +1, -1, -1 }, { +1, +1, -1 }, { +1, +1, +1 } },
+        { { -1, -1, -1 }, { -1, -1, +1 }, { -1, +1, +1 }, { -1, +1, -1 } },
+        { { +1, -1, +1 }, { -1, -1, +1 }, { -1, -1, -1 }, { +1, -1, -1 } },
+        { { -1, -1, +1 }, { +1, -1, +1 }, { +1, +1, +1 }, { -1, +1, +1 } }
+    };
+    for (int i = 0; i < 6; ++i) {
+        glColor3ub( i*20, 100+i*10, i*42 );
+        glBegin( GL_QUADS );
+        for (int j = 0; j < 4; ++j) {
+            glVertex3d(
+                        0.2 * coords[i][j][0],
+                    0.2 * coords[i][j][1],
+                    0.2 * coords[i][j][2]
+                    );
+        }
+        glEnd();
+    }
+}
+
+void on_trackbar( int, void* ) {
+    cv::updateWindow( "Example 9-4" );
+}
+
+void help(char ** argv) {
+    cout << "Call: " << argv[0] << " <image>" << endl;
+    cout << "Here OpenGL is used to render a cube on top of an image.\n"
+         << "User can rotate the cube with the sliders" <<endl;
+}
+
+int main(int argc, char* argv[])
+{
+    if(argc != 2) {
+        help (argv);
+        return -1;
     }
-    glEnd();
-  }
+
+    cv::Mat img = cv::imread(argv[1]);
+    if( img.empty() ) {
+        cout << "Cannot load " << argv[1] << endl;
+        return -1;
+    }
+
+    cv::namedWindow( "Example 9-4", CV_WINDOW_OPENGL );
+    cv::resizeWindow("Example 9-4", img.cols, img.rows);
+    cv::createTrackbar( "X-rotation", "Example 9-4", &rotx, 360, on_trackbar);
+    cv::createTrackbar( "Y-rotation", "Example 9-4", &roty, 360, on_trackbar);
+
+    cv::ogl::Texture2D backgroundTex(img);
+    cv::setOpenGlDrawCallback("Example 9-4", on_opengl, &backgroundTex);
+    cv::updateWindow("Example 9-4");
+
+    cv::waitKey(0);
+
+    cv::setOpenGlDrawCallback("Example 9-4", 0, 0);
+    cv::destroyAllWindows();
+
+    return 0;
 }