From 98a312094ea4c8676fba77173c55d132a2edf310 Mon Sep 17 00:00:00 2001
From: Trygve <trygve@posteo.net>
Date: Sun, 28 Apr 2024 22:30:37 +0200
Subject: [PATCH] Added box blur

---
 src/HeightMap.cpp      | 44 +++++++++++++++++++++++++++++++++++++++++-
 src/contour_creator.hh |  1 +
 src/main.cpp           |  5 +++--
 3 files changed, 47 insertions(+), 3 deletions(-)

diff --git a/src/HeightMap.cpp b/src/HeightMap.cpp
index f4b4975..017a0a4 100644
--- a/src/HeightMap.cpp
+++ b/src/HeightMap.cpp
@@ -1,7 +1,7 @@
 #include <gdal/cpl_conv.h>
 #include <iostream>
 #include <stdexcept>
-
+#include <omp.h>
 #include <gdal/gdal.h>
 #include "gdal/gdal_priv.h"
 #include <gdal/gdal_frmts.h>
@@ -48,4 +48,46 @@ float HeightMap::get_pixel(int x, int y)
     int offset = ((this->width * y) + x);
     //std::cout << "  offset: " << offset << " " << x << ","<< y;
     return *(this->data + offset);
+}
+
+void HeightMap::blur(float standard_deviation)
+{
+    // standard_deviation does not do anything yet. This is currently a simple box blur
+    int kernel_height = 5;
+    int kernel_width = 5;
+    int kernel_size = kernel_height*kernel_width;
+    float* kernel = (float*) CPLMalloc(sizeof(float)*kernel_size);
+    for (int i=0; i<kernel_size; i++)
+    {
+        *(kernel + i) = 1.0;
+    }
+
+    float* blurred = (float *) CPLMalloc(sizeof(float)*this->width*this->height);
+    #pragma omp parallel
+    {
+    #pragma omp for
+    for (int i = 0; i < this->height * this->width; i++)
+    {
+        float blurred_pixel = 0;
+        for (int j = 0; j < kernel_size; j++)
+        {
+            int x = j%kernel_width - kernel_width/2 + i%this->width;
+            int y = j/kernel_width - kernel_height/2 + i/this->width;
+            if (x<0 || x>=this->width)
+            {
+                x = 0;
+            }
+            
+            if (y<0 || y>=this->height)
+            {
+                y = 0;
+            }
+            blurred_pixel += this->get_pixel(x, y);
+        }
+        *(blurred + i) = blurred_pixel/float(kernel_size);
+    }
+    }
+    free(this->data);
+    this->data = blurred;
+    blurred = nullptr;
 }
\ No newline at end of file
diff --git a/src/contour_creator.hh b/src/contour_creator.hh
index 7ab598b..87d5066 100644
--- a/src/contour_creator.hh
+++ b/src/contour_creator.hh
@@ -19,6 +19,7 @@ class HeightMap
 
         HeightMap(const char* filepath);
         float get_pixel(int x,int y);
+        void blur(float standard_deviation);
 };
 
 /**
diff --git a/src/main.cpp b/src/main.cpp
index 15049e5..bea1db9 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -80,8 +80,7 @@ constexpr std::tuple<double, double, double, double> marching_squares_lookup(int
         case 12: return {0, 0.5, 1, 0.5};
         case 13: return {0.5, 0, 1, 0.5};
         case 14: return {0, 0.5, 0.5, 0};
-    }
-    
+    };
 }
 void write_output_file(std::vector<CellMap> cellmaps, const char *filepath)
 {
@@ -185,6 +184,8 @@ int main(int argc, const char* argv[])
     std::cout << "x: " << map.width << "    y: " << map.height << "\n";
     std::cout << "max: " << map.max << "    min: " << map.min << "\n";
     
+    map.blur(0.8);
+    
     auto cellmap = produce_cellmap(&map, 40);
     /*
     for (int y = 0; y < cellmap.height; y++)