From 623fc8c73de35bef0785f09bae8a3f607f8ed087 Mon Sep 17 00:00:00 2001
From: Wolfgang Draxinger <Wolfgang.Draxinger@draxit.de>
Date: Fri, 27 Apr 2012 20:43:08 +0200
Subject: qt_terr - a simple quadtree based terrain renderer with LOD

---
 samples/OpenGL/qt_terr/quad.cpp | 140 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 140 insertions(+)
 create mode 100644 samples/OpenGL/qt_terr/quad.cpp

(limited to 'samples/OpenGL/qt_terr/quad.cpp')

diff --git a/samples/OpenGL/qt_terr/quad.cpp b/samples/OpenGL/qt_terr/quad.cpp
new file mode 100644
index 0000000..e57bcfa
--- /dev/null
+++ b/samples/OpenGL/qt_terr/quad.cpp
@@ -0,0 +1,140 @@
+#include <stdlib.h>
+#include "quad.h"
+
+Quad::Quad() :
+	V(new std::vector<double>)
+{
+	quads[0][0] =
+	quads[0][1] =
+	quads[1][0] =
+	quads[1][1] = 0;
+
+	unsigned int V_old_size = V->size();
+	unsigned int V_new_size = V_old_size + 9;
+	V->resize(V_new_size, 0.);
+
+	v1_offset = V_new_size - 3*3;
+	v2_offset = V_new_size - 2*3;
+	v_mid_offset = V_new_size - 1*3;
+
+	set_range(0., 1., 0., 1.);
+}
+
+Quad::Quad( std::vector<double> * const V_) :
+	V(V_)
+{
+	quads[0][0] =
+	quads[0][1] =
+	quads[1][0] =
+	quads[1][1] = 0;
+
+	unsigned int V_old_size = V->size();
+	unsigned int V_new_size = V_old_size + 9;
+	V->resize(V_new_size, 0.);
+
+	v1_offset = V_new_size - 3*3;
+	v2_offset = V_new_size - 2*3;
+	v_mid_offset = V_new_size - 1*3;
+
+	set_range(0., 1., 0., 1.);
+}
+
+Quad::Quad(Quad &q) :
+	V(new std::vector<double>)
+{
+	operator= (q);
+}
+
+Quad::~Quad()
+{
+	if(is_split())
+	{
+		delete quads[0][0];
+		delete quads[0][1];
+		delete quads[1][0];
+		delete quads[1][1];
+	}
+}
+
+Quad& Quad::operator=(Quad &q)
+{
+	*x1() = *q.x1();
+	*x2() = *q.x2();
+	*y1() = *q.y1();
+	*y2() = *q.y2();
+
+	if( q.is_split() )
+	{
+		split();		
+		quads[0][0] = q.quads[0][0];
+		quads[0][1] = q.quads[0][1];
+		quads[1][0] = q.quads[1][0];
+		quads[1][1] = q.quads[1][1];
+	}
+
+	return *this;
+}
+
+void Quad::split()
+{
+	if(is_split())
+		return;
+
+	quads[0][0] = new Quad(V);
+	quads[0][1] = new Quad(V);
+	quads[1][0] = new Quad(V);
+	quads[1][1] = new Quad(V);
+	
+	quads[0][0]->set_range( *x1(), *x_mid(), *y1(), *y_mid() );
+	quads[0][1]->set_range( *x_mid(), *x2(), *y1(), *y_mid() );
+	quads[1][0]->set_range( *x1(), *x_mid(), *y_mid(), *y2() );
+	quads[1][1]->set_range( *x_mid(), *x2(), *y_mid(), *y2() );
+}
+
+bool Quad::is_split()
+{
+	return	quads[0][0] &&
+	        quads[0][1] &&
+	        quads[1][0] &&
+	        quads[1][1];
+}
+
+void Quad::set_range(double nx1, double nx2, double ny1, double ny2)
+{
+	*x1() = nx1;
+	*x2() = nx2;
+	*y1() = ny1;
+	*y2() = ny2;
+	*x_mid() = ( *x1() + *x2() )*0.5f;
+	*y_mid() = ( *y1() + *y2() )*0.5f;
+
+}
+
+void Quad::track_down(double x, double y, int levels)
+{
+	if(levels>0)
+	{
+		int a = ( x < *x_mid() ) ? 0 : 1;
+		int b = ( y < *y_mid() ) ? 0 : 1;
+
+		if( !is_split() )
+			split();
+
+		quads[b][a]->track_down(x, y, levels-1);
+	}
+}
+
+Quad *Quad::get_at(double x, double y, int max_level, int level)
+{
+	if(!is_split())
+		return this;
+
+	/*if(max_level>-1 && level>=max_level)
+		return this;*/
+
+	int a = ( x < *x_mid() ) ? 0 : 1;
+	int b = ( y < *y_mid() ) ? 0 : 1;
+
+	return quads[b][a]->get_at(x, y, max_level, level+1);
+}
+
-- 
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