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simple cube creation using opengl Qt

Started by phani433, Mar 15 2012 03:58 AM

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#1 phani433 Members - Reputation: 100

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Posted 15 March 2012 - 03:58 AM

hi, i am new to opengl ..i just started one simple program of creating a cube with different colors in different sides.. i tried with the following code but it showing yellow color square..some one please tell how to make it 3D..

GLWidget::GLWidget(QWidget *parent) :
	QGLWidget(parent)
{
	rtri = rquad = 0.0f;
}
void GLWidget::initializeGL()
{
	glClearColor(1,1,1,1);
}
void GLWidget::paintGL()
{
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
	glLoadIdentity();
	glTranslatef(1.5f,0.0f,-7.0f);
	glRotatef(rtri,0.0f,1.0f,0.0f);
	glBegin(GL_QUADS);

	   glColor3f(0.0f,1.0f,0.0f);		  // Set The Color To Green
	   glVertex3f( 1.0f, 1.0f,-1.0f);		  // Top Right Of The Quad (Top)
	   glVertex3f(-1.0f, 1.0f,-1.0f);		  // Top Left Of The Quad (Top)
	   glVertex3f(-1.0f, 1.0f, 1.0f);		  // Bottom Left Of The Quad (Top)
	   glVertex3f( 1.0f, 1.0f, 1.0f);		  // Bottom Right Of The Quad (Top)

	   glColor3f(1.0f,0.5f,0.0f);		  // Set The Color To Orange
	   glVertex3f( 1.0f,-1.0f, 1.0f);		  // Top Right Of The Quad (Bottom)
	   glVertex3f(-1.0f,-1.0f, 1.0f);		  // Top Left Of The Quad (Bottom)
	   glVertex3f(-1.0f,-1.0f,-1.0f);		  // Bottom Left Of The Quad (Bottom)
	   glVertex3f( 1.0f,-1.0f,-1.0f);		  // Bottom Right Of The Quad (Bottom)
	   glColor3f(1.0f,0.0f,0.0f);		  // Set The Color To Red
	   glVertex3f( 1.0f, 1.0f, 1.0f);		  // Top Right Of The Quad (Front)
	   glVertex3f(-1.0f, 1.0f, 1.0f);		  // Top Left Of The Quad (Front)
	   glVertex3f(-1.0f,-1.0f, 1.0f);		  // Bottom Left Of The Quad (Front)
	   glVertex3f( 1.0f,-1.0f, 1.0f);		  // Bottom Right Of The Quad (Front)
	   glColor3f (1.0f,1.0f,0.0f);		  // Set The Color To Yellow
	   glVertex3f( 1.0f,-1.0f,-1.0f);		  // Bottom Left Of The Quad (Back)
	   glVertex3f(-1.0f,-1.0f,-1.0f);		  // Bottom Right Of The Quad (Back)
	   glVertex3f(-1.0f, 1.0f,-1.0f);		  // Top Right Of The Quad (Back)
	   glVertex3f( 1.0f, 1.0f,-1.0f);		  // Top Left Of The Quad (Back)
	   glColor3f(0.0f,0.0f,1.0f);		  // Set The Color To Blue
	   glVertex3f(-1.0f, 1.0f, 1.0f);		  // Top Right Of The Quad (Left)
	   glVertex3f(-1.0f, 1.0f,-1.0f);		  // Top Left Of The Quad (Left)
	   glVertex3f(-1.0f,-1.0f,-1.0f);		  // Bottom Left Of The Quad (Left)
	   glVertex3f(-1.0f,-1.0f, 1.0f);		  // Bottom Right Of The Quad (Left)
	   glColor3f(1.0f,0.0f,1.0f);		  // Set The Color To Violet
	   glVertex3f( 1.0f, 1.0f,-1.0f);		  // Top Right Of The Quad (Right)
	   glVertex3f( 1.0f, 1.0f, 1.0f);		  // Top Left Of The Quad (Right)
	   glVertex3f( 1.0f,-1.0f, 1.0f);		  // Bottom Left Of The Quad (Right)
	   glVertex3f( 1.0f,-1.0f,-1.0f);		  // Bottom Right Of The Quad (Right)

	 glEnd();
	 rquad-=0.15f;					   // Decrease The Rotation Variable For The Quad
}
void GLWidget::resizeGL(int w, int h)
{
	   double Aspect;
	// Prevent a divide by zero, when window is too short
	// (you cant make a window of zero width)
		if(h == 0)//altura
			h = 1;
			// Set the viewport to be the entire window
		glViewport(0, 0, w, h);

		Aspect=(double)w/(double)h;
		//Reset projection matrix stack
		glMatrixMode(GL_PROJECTION);
		// Reset the coordinate system before modifying
		glLoadIdentity();

	   // gluPerspective(45.0f,Aspect, 1.0, 425.0);
		 double Range = 10;
		if (w <= h)
			glOrtho(-(Range),Range,-Range/Aspect,Range/Aspect,-(Range*2),Range*2);
		else
			glOrtho(-(Range*Aspect),Range*Aspect,-Range,Range,-(Range*2),Range*2);
		glMatrixMode(GL_MODELVIEW);
		glLoadIdentity();
}

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#2 JustinDaniel Members - Reputation: 136

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Posted 15 March 2012 - 06:05 AM

What you see in the computer is Only 2D so, if you have placen the cube straight ahead you will only see a Square, To see the 3D shape probably try using

glRotatef( 45, 0, 1, 0 );

That will bring a 3D looking model ;)

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#3 phani433 Members - Reputation: 100

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Posted 15 March 2012 - 07:32 AM

Thanks for your valuble reply now i am seeing my cube in 3d manner..how to create rotating cube with time

#4 JustinDaniel Members - Reputation: 136

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Posted 15 March 2012 - 08:35 AM

Thanks for your valuble reply now i am seeing my cube in 3d manner..how to create rotating cube with time

That'd be simple, just create a variable and update it, pass it to the Rotate function.

double angle = 0.0;
glRotatef(angle, 0, 1, 0);
//Init...
angle++;

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#5 phani433 Members - Reputation: 100

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Posted 15 March 2012 - 08:59 PM

Thanks rotation is also working ..i had one doubt with out rotation ,transalation we can see only one side ..which side we can see with out ratation? and also i given green color to the top face but it is not showing green color..but remaining faces it showing different colors which are all i given in the program..some one please tell me why green is not showing..

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#6 JustinDaniel Members - Reputation: 136

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Posted 15 March 2012 - 11:47 PM

That is because you are rotating only in the Y- direction, Try changing to Z or X direction or both.

glRotatef(angle, 1, 0, 0);
// or
glRotatef(angle. 0, 0, 1);

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#7 phani433 Members - Reputation: 100

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Posted 15 March 2012 - 11:54 PM

i tried it but i am unable to see the green color..tell me one thing with out rotation and tanslate(static cube)..which face is visible..

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#8 JustinDaniel Members - Reputation: 136

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Posted 16 March 2012 - 12:05 AM

i tried it but i am unable to see the green color..tell me one thing with out rotation and tanslate(static cube)..which face is visible..

If the cubes not rotating , then its obvious that the front face will only be visible.

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#9 phani433 Members - Reputation: 100

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Posted 16 March 2012 - 12:16 AM

in the program i given red for front face but with out rotation it showing yellow(which is back face).sorry for irritating you.

#include "glwidget.h"
GLWidget::GLWidget(QWidget *parent) :
    QGLWidget(parent)
{
    rtri = rquad = 0.0f;
	 timer = new QTimer(this);
    connect(timer, SIGNAL(timeout()), this, SLOT(advancecube()));
    timer->start(20);

}
void GLWidget::initializeGL()
{
    glClearColor(1,1,1,1);
}
void GLWidget::paintGL()
{
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glLoadIdentity();
    glTranslatef(1.5f,0.0f,-7.0f);
    glRotatef( rquad, 0, 0, 1 );

    glBegin(GL_QUADS);
	    glColor3f (0.0f,1.0f,0.0f);		  // Set The Color To Green
	   glVertex3f( 1.0f, 1.0f,-1.0f);		  // Top Right Of The Quad (Top)
	   glVertex3f(-1.0f, 1.0f,-1.0f);		  // Top Left Of The Quad (Top)
	   glVertex3f(-1.0f, 1.0f, 1.0f);		  // Bottom Left Of The Quad (Top)
	   glVertex3f( 1.0f, 1.0f, 1.0f);		  // Bottom Right Of The Quad (Top)

	   glColor3f(1.0f,0.5f,0.0f);		  // Set The Color To Orange
	   glVertex3f( 1.0f,-1.0f, 1.0f);		  // Top Right Of The Quad (Bottom)
	   glVertex3f(-1.0f,-1.0f, 1.0f);		  // Top Left Of The Quad (Bottom)
	   glVertex3f(-1.0f,-1.0f,-1.0f);		  // Bottom Left Of The Quad (Bottom)
	   glVertex3f( 1.0f,-1.0f,-1.0f);		  // Bottom Right Of The Quad (Bottom)
	   glColor3f(1.0f,0.0f,0.0f);		  // Set The Color To Red
	   glVertex3f( 1.0f, 1.0f, 1.0f);		  // Top Right Of The Quad (Front)
	   glVertex3f(-1.0f, 1.0f, 1.0f);		  // Top Left Of The Quad (Front)
	   glVertex3f(-1.0f,-1.0f, 1.0f);		  // Bottom Left Of The Quad (Front)
	   glVertex3f( 1.0f,-1.0f, 1.0f);		  // Bottom Right Of The Quad (Front)
	   glColor3f (1.0f,1.0f,0.0f);		  // Set The Color To Yellow
	   glVertex3f( 1.0f,-1.0f,-1.0f);		  // Bottom Left Of The Quad (Back)
	   glVertex3f(-1.0f,-1.0f,-1.0f);		  // Bottom Right Of The Quad (Back)
	   glVertex3f(-1.0f, 1.0f,-1.0f);		  // Top Right Of The Quad (Back)
	   glVertex3f( 1.0f, 1.0f,-1.0f);		  // Top Left Of The Quad (Back)
	   glColor3f(0.0f,0.0f,1.0f);		  // Set The Color To Blue
	   glVertex3f(-1.0f, 1.0f, 1.0f);		  // Top Right Of The Quad (Left)
	   glVertex3f(-1.0f, 1.0f,-1.0f);		  // Top Left Of The Quad (Left)
	   glVertex3f(-1.0f,-1.0f,-1.0f);		  // Bottom Left Of The Quad (Left)
	   glVertex3f(-1.0f,-1.0f, 1.0f);		  // Bottom Right Of The Quad (Left)
	   glColor3f(1.0f,0.0f,1.0f);		  // Set The Color To Violet
	   glVertex3f( 1.0f, 1.0f,-1.0f);		  // Top Right Of The Quad (Right)
	   glVertex3f( 1.0f, 1.0f, 1.0f);		  // Top Left Of The Quad (Right)
	   glVertex3f( 1.0f,-1.0f, 1.0f);		  // Bottom Left Of The Quad (Right)
	   glVertex3f( 1.0f,-1.0f,-1.0f);		  // Bottom Right Of The Quad (Right)

	 glEnd();
}
void GLWidget::resizeGL(int w, int h)
{
	   double Aspect;
    // Prevent a divide by zero, when window is too short
    // (you cant make a window of zero width)
	    if(h == 0)//altura
		    h = 1;
		    // Set the viewport to be the entire window
	    glViewport(0, 0, w, h);

	    Aspect=(double)w/(double)h;
	    //Reset projection matrix stack
	    glMatrixMode(GL_PROJECTION);
	    // Reset the coordinate system before modifying
	    glLoadIdentity();

	   // gluPerspective(45.0f,Aspect, 1.0, 425.0);
		 double Range = 10;
	    if (w <= h)
		    glOrtho(-(Range),Range,-Range/Aspect,Range/Aspect,-(Range*2),Range*2);
	    else
		    glOrtho(-(Range*Aspect),Range*Aspect,-Range,Range,-(Range*2),Range*2);
	    glMatrixMode(GL_MODELVIEW);
	    glLoadIdentity();
}
void GLWidget::advancecube()
{
    rquad++;
    updateGL();
}

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#10 JustinDaniel Members - Reputation: 136

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Posted 16 March 2012 - 12:58 AM

Really? It works for me, I tried the code and the front face is red, See if you have projected the matrix properly.

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#11 phani433 Members - Reputation: 100

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Posted 16 March 2012 - 01:37 AM

could you please send me the code what ever you are trid

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#12 Talei Members - Reputation: 267

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Posted 18 March 2012 - 10:31 AM

Source code for Qt project with OpenGL (rotating cube) that could help You is here: http://blog.lugru.co...-and-qglwidget/

Good luck.

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