Corrected an error where the root process was rendering too much.

server/mandel_render_srv.cpp

@@ -11,7 +11,7 @@ using namespace Magick;
 
 mandel_render_srv::mandel_render_srv(std::string host, unsigned int port,
                                      int id, int procs, QObject* parent) :
-    QObject(parent), settings(settings), id(id), procs(procs)
+    QObject(parent), id(id), procs(procs)
 {
     // We only let the root process connect to the client.
     if (id == 0)
@@ -57,17 +57,17 @@ void mandel_render_srv::start_drawing()
 
 void mandel_render_srv::root_process_handling(unsigned long *receive_buffer)
 {
-    Image my_image(Geometry(settings.img_width, settings.img_height), "white");
+    Image my_image(Geometry(settings.img_width, settings.img_height * procs), "white");
     my_image.modifyImage();
 
     Pixels pixel_cache(my_image);
-    PixelPacket *pixels = pixel_cache.get(0, 0, settings.img_width, settings.img_height);
+    PixelPacket *pixels = pixel_cache.get(0, 0, settings.img_width, settings.img_height * procs);
 
     cout << "Assembling image!" << endl;
-    for (unsigned long y = 0; y < settings.img_height; ++y)
+    for (unsigned long y = 0; y < settings.img_height * procs; ++y)
     {
         cout << "Progress: " << setprecision(3) << 
-            static_cast<float>(y * 100) / (settings.img_height) << " %            \r" << flush;
+            static_cast<float>(y * 100) / (settings.img_height * procs) << " %            \r" << flush;
 
         for (unsigned long x = 0; x < settings.img_width; ++x)
         {
@@ -155,6 +155,8 @@ void mandel_render_srv::handle_recv_data()
 
             settings = recv_settings;
 
+            settings.img_height /= procs;
+
             double mpi_data[8];
 
             mpi_data[0] = static_cast<double>(mpi_opcodes::RENDER);
@@ -163,7 +165,7 @@ void mandel_render_srv::handle_recv_data()
             mpi_data[3] = settings.im_max;
             mpi_data[4] = settings.im_min;
             mpi_data[5] = settings.img_width;
-            mpi_data[6] = settings.img_height / procs;
+            mpi_data[6] = settings.img_height;
             mpi_data[7] = settings.iterations;
 
             // Send current render settings to other processes.
@@ -173,6 +175,12 @@ void mandel_render_srv::handle_recv_data()
                     MPI_Send(mpi_data, 8, MPI_DOUBLE, i, 0, MPI_COMM_WORLD);
             }
 
+            // Update the settings for the root process.
+            double im_max = settings.im_max;
+            double im_min = settings.im_min;
+            settings.im_max = get_max_im(im_max, im_min, 0, procs);
+            settings.im_min = get_min_im(im_max, im_min, 0, procs);
+
             start_drawing();
             break;
         }