# How to draw 3d line(x,y,z)

• i can draw the 2d line and i want to draw 3d (x,y,z) dimension for graph the math equation..

Where i should start ?
there is some explanation
http://www.digitalfanatics.org/projects/qt_tutorial/chapter14.html

but it is too complex.. i need to draw just line on (x,y,z) dimention..

• to draw on 3D you have to learn some basics. then things will get easier. The link which you have given seems good. Just try to implement examples then you'll see how easy to draw a 3d line.

• This simple app should get you started with drawing lines in 3D using OpenGL and Qt. I suggest you also have a read through the QGLWidget docs and get yourself a good book on OpenGL programming. I can recommend the OpenGL Superbible.

== main.cpp ==
@
#include <QtGui/QApplication>
#include "lines.h"

int main(int argc, char *argv[])
{
QApplication a(argc, argv);
Lines w;
w.show();
return a.exec();
}
@

== lines.h ==
@
#ifndef LINES_H
#define LINES_H

#include <QGLWidget>
#include <QVector2D>

const float pi = 3.141592653f;
const float twoPi = 2.0f * pi;
const float piBy2 = 0.5f * pi;
const float degToRad = pi / 180.0f;
const float radToDeg = 180.0f / pi;

class Lines : public QGLWidget
{
Q_OBJECT

public:
Lines( QWidget* parent = 0 );

protected:
virtual void initializeGL();
virtual void resizeGL( int w, int h );
virtual void paintGL();

``````virtual void keyPressEvent( QKeyEvent* e );
``````

private:
float m_theta; /< Rotation about x-axis */
float m_phi; /
float m_aspectRatio;
QVector2D m_lineWidthRange;
float m_lineWidthStep;
float m_lineWidth;
};

#endif // LINES_H
@

== lines.cpp ==
@
#include "lines.h"

#include <QCoreApplication>
#include <QDebug>
#include <QKeyEvent>

#include <math.h>

Lines::Lines( QWidget* parent )
: QGLWidget( parent ),
m_theta( 0.0f ),
m_phi( 0.0f ),
m_aspectRatio( 1.0 ),
m_lineWidthRange(),
m_lineWidthStep( 0.0f ),
m_lineWidth( 1.0f )
{
}

void Lines::initializeGL()
{
// Set the clear color to black
glClearColor( 0.0f, 0.0f, 0.0f, 1.0f );

``````// Set the drawing color to green
glColor3f( 0.0f, 1.0f, 0.0f );

// Query some info about supported point sizes
glGetFloatv( GL_LINE_WIDTH_RANGE, reinterpret_cast<float*>( &m_lineWidthRange ) );
glGetFloatv( GL_LINE_WIDTH_GRANULARITY, &m_lineWidthStep );

qDebug() << "Point size range:" << m_lineWidthRange;
qDebug() << "Point size step:" << m_lineWidthStep;

m_lineWidth = m_lineWidthRange.x();
``````

}

void Lines::resizeGL( int w, int h )
{
// Prevent a divde by zero
if ( h == 0 )
h = 1;

``````// Set the viewport to window dimensions
glViewport( 0, 0, w, h );

// reset the coordinate system
glMatrixMode( GL_PROJECTION );

// Establish the clipping volume by setting up an orthographic projection
double range = 100.0;
m_aspectRatio = double( w ) / double( h );
if ( w <=h )
glOrtho( -range, range, -range / m_aspectRatio, range / m_aspectRatio, range, -range );
else
glOrtho( -range * m_aspectRatio, range * m_aspectRatio, -range, range, range, -range );

glMatrixMode( GL_MODELVIEW );
``````

}

void Lines::paintGL()
{
// Clear the buffer with the current clearing color
glClear( GL_COLOR_BUFFER_BIT );

``````// Set drawing colour to red
glColor3f( 1.0f, 0.0f, 0.0f );

// Save matrix state and do the custom rotation
glPushMatrix();
glRotatef( m_theta, 1.0f, 0.0f, 0.0f );
glRotatef( m_phi,   0.0f, 1.0f, 0.0f );

// Draw some Lines in a helix
glLineWidth( m_lineWidth );
glBegin( GL_LINE_STRIP );
float z = -50.0f;
float angle = 0.0f;
for ( angle = 0.0f; angle <= twoPi * 3.0f; angle += 0.1f, z += 0.5f )
{
float x = 50.0 * sin( angle );
float y = 50.0 * cos( angle );
glVertex3f( x, y, z );
}
glEnd();

// Restore the matrix state
glPopMatrix();
``````

}

void Lines::keyPressEvent( QKeyEvent* e )
{
switch ( e->key() )
{
case Qt::Key_Escape:
QCoreApplication::instance()->quit();
break;

``````    case Qt::Key_Left:
m_phi += 1.0f;
updateGL();
break;

case Qt::Key_Right:
m_phi -= 1.0f;
updateGL();
break;

case Qt::Key_Up:
m_theta += 1.0f;
updateGL();
break;

case Qt::Key_Down:
m_theta -= 1.0f;
updateGL();
break;

case Qt::Key_Plus:
m_lineWidth = qMin( m_lineWidth + m_lineWidthStep, float( m_lineWidthRange.y() ) );
qDebug() << "m_lineWidth =" << m_lineWidth;
updateGL();
break;

case Qt::Key_Minus:
m_lineWidth = qMax( m_lineWidth - m_lineWidthStep, float( m_lineWidthRange.x() ) );
qDebug() << "m_lineWidth =" << m_lineWidth;
updateGL();
break;

default:
QGLWidget::keyPressEvent( e );
}
``````

}
@

• @ZapB thank you very much... its awesome :)
@hakan ayrıca teşekkür ederim hakan bey yorumunuz için.

• No problem. Good luck with OpenGL it is good fun although it can be confusing and frustrating to start with when you spend a long time coding something only to be presented with an empty window ;-)