# HG changeset patch
# User Eleni Maria Stea <elene.mst@gmail.com>
# Date 1408347851 -10800
# Node ID eb87d4a12bd39f029392866a1bdadaa18d8285da
# Parent  3e4eb9a0d99999640ece00a17b74e55c10e158d9
histogram

diff -r 3e4eb9a0d999 -r eb87d4a12bd3 src/main.cc
--- a/src/main.cc	Sun Aug 17 02:25:01 2014 +0300
+++ b/src/main.cc	Mon Aug 18 10:44:11 2014 +0300
@@ -468,6 +468,23 @@
 		high = thres;
 	}
 
+
+	//drawing the histogram
+	float hmax = 1 / (float)vol->max_histogram_value;
+
+	glBegin(GL_QUADS);
+	for (int i=0; i<HIST_SIZE; i++) {
+		float x0 = (float)i / HIST_SIZE;
+		float x1 = (float)(i + 1) / HIST_SIZE;
+
+		glColor3f(0.3, 0.3, 0.3);
+		glVertex3f(x0, 0, 0);
+		glVertex3f(x1, 0, 0);
+		glVertex3f(x1, hmax * vol->histogram[i + 1], 0);
+		glVertex3f(x0, hmax * vol->histogram[i], 0);
+	}
+	glEnd();
+
 	//drawing the transfer function curve
 
 	glLineWidth(3);
diff -r 3e4eb9a0d999 -r eb87d4a12bd3 src/volume.cc
--- a/src/volume.cc	Sun Aug 17 02:25:01 2014 +0300
+++ b/src/volume.cc	Mon Aug 18 10:44:11 2014 +0300
@@ -4,6 +4,7 @@
 
 #include <ctype.h>
 #include <errno.h>
+#include <float.h>
 #include <stdio.h>
 #include <string.h>
 
@@ -24,6 +25,9 @@
 	x_rot = 0;
 	vol_tex_valid = false;
 
+	memset(histogram, 0, HIST_SIZE * sizeof(int));
+	max_histogram_value = 0;
+
 	glGenTextures(1, &vol_tex);
 }
 
@@ -55,6 +59,31 @@
 	}
 }
 
+void Volume::create_histogram()
+{
+	if (slices.empty())
+		return;
+
+	for (size_t i=0; i<slices.size(); i++)
+	{
+		float *slice_pixels = (float*)slices[i].get_pixels();
+		for (int j=0; j < width * height; j++)
+		{
+			float val = slice_pixels[j];
+
+			int ival = (int)(val * 256);
+			histogram[ival]++;
+		}
+	}
+
+	max_histogram_value = 0;
+	for (int i=0; i<HIST_SIZE; i++) {
+		if (i < 10)
+			continue;
+		max_histogram_value = std::max(max_histogram_value, histogram[i]);
+	}
+}
+
 bool Volume::load(const char *fname)
 {
 	char up = 'y';
@@ -110,6 +139,7 @@
 	if (up == 'z')
 		x_rot = 90;
 
+	create_histogram();
 	return true;
 }
 
diff -r 3e4eb9a0d999 -r eb87d4a12bd3 src/volume.h
--- a/src/volume.h	Sun Aug 17 02:25:01 2014 +0300
+++ b/src/volume.h	Mon Aug 18 10:44:11 2014 +0300
@@ -4,6 +4,8 @@
 #include <vector>
 #include "image.h"
 
+#define HIST_SIZE 256
+
 class Mesh;
 
 class Volume {
@@ -21,6 +23,10 @@
 	void create_vol_tex() const;
 
 public:
+	int histogram[HIST_SIZE];
+	int max_histogram_value;
+
+public:
 	Volume();
 	~Volume();
 
@@ -43,6 +49,7 @@
 
 	void create_mesh(Mesh *mesh, float tmin, float tmax, int xres, int yres, int zres);
 
+	void create_histogram();
 	void draw() const;
 };