Line adjusting in real time

any other suggestions for real-time? thanks a lot.

Let me code the the little radius for check-range because it is hard for user to click on same point. So I will give a vicinity around it.
 Also, i Will use right mouse button as u suggest Ike. I will get back when i finish those basic steps.

hi ike,
 FIrst of all, i update my code a little bit to make sure no duplicate point in vector. Done.
 now i try to use the glutMotionFunc  with active motion in order to get new point. However, glutMotionFunc give a lot of points as long as  drag the mouse. Am i on the right track?
 
PS: do u i know left mouse or right mouse? in processMouse, we didn't indicate left or  right mouse!!!

>> now i try to use the glutMotionFunc  with active motion in order to get new point. However, glutMotionFunc give a lot of points as long as  drag the mouse. Am i on the right track?
 
Start with moust button up and down. You dont need glutMotionFunc for that. Just pick the point where the mouse was down and see if there is one of your points nearby. If there is a point catch the mouse up and its x & y for the selected point.

The mouse-button identifier is the first param of your mouse callback function processMouse, called button. The Ids are defined in glut.h you can check it like this:

void processMouse(int button, int state, int x, int y) {
 
    switch(button)
    {
        case GLUT_LEFT_BUTTON:
            // put code for left button here
            break;

        case GLUT_MIDDLE_BUTTON:
            // put code for middle button here
            break;

        case GLUT_RIGHT_BUTTON:
            // put code for right button here
            break;
    }

I cant check your code now, I'm about to go to work ;)
Can you tell me what the problem is and what works so far?

i am upgrading my code. i am working on your guide " start with mouse down and mouse up.."

have a good day.

Ok, similar to the check for duplicate elements in vector for GLUT_LEFT_BUTTON, add a block for the right button and check there if user clicked a point (if x & y is already in the vector), if yes, store the index of the point in a global variable and in mouse button up replace the point at that index with the new x & y

add a global variable like:

int selectedPointIndex = -1;

Use -1 to indicate if a point is selected, if selectedPointIndex == -1, it means no point is selected, otherwise it is the index of the currently selected point

please take look at my code :)

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <math.h>
 
#include <GL/glut.h>
#include <vector>
 
struct point
{
        int x;
        int y;
};
 
        std::vector <point> points;
        point OnePoint;  
		point TempPoint;
		point FinalPoint;
		int selectedPointIndex = -1;
 
void init (void)
{
      glClearColor (1.0,1.0,1.0,0.0);
 
}
 
void lineSegment (void)
{
     
	  glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 
      glColor3f(1.0,0.0,0.0);           
 
      glBegin(GL_LINE_STRIP);
                for(int i =0; i < points.size();i++)
                {
                        glVertex2i(points[i].x, points[i].y);
                }
           
      glEnd();
      
      glFlush();
}
 
void processMouse(int button, int state, int x, int y) {
 
      if (state == GLUT_DOWN)
      {
		  if(button == GLUT_LEFT_BUTTON)
		  {
				  // check to avoid duplicate elements in vector
				  bool _bfound = false;
 
				  for (int ii = 0; ii < points.size(); ii++)
				  {	 
					  if( points[ii].x == x && points[ii].y == y)
					  {
						  _bfound = true;
						  printf("Duplicate element!!!\n");
						  break;
					  }
				  }
 
				  if( _bfound == false)
				  {
					  OnePoint.x= x;
					  OnePoint.y= y; 
					  points.push_back(OnePoint);
				  }  
		  }
		  
		  if(button == GLUT_RIGHT_BUTTON)
		  {
			  printf("Right click on mouse\n");
 
			  printf("PRESSMOUSE x is %d\n",x);
			  printf("PRESSMOUSE y is %d\n",y);
			  
			  TempPoint.x= x;
			  TempPoint.y= y;
 
		  }
	  }
 
	  if( state == GLUT_UP)
	  {
		  if(button == GLUT_RIGHT_BUTTON)
		  {
			  printf("RELEASEMOUSE x is %d\n",x);
			  printf("RELEASEMOUSE y is %d\n",y);
 
			  FinalPoint.x = x;
			  FinalPoint.y  = y;
 
		  }
	  }
 
	  //check to see it TempPoint is in vector or not
		for (int iii = 0; iii < points.size(); iii++)
		{
			// use approximately difference is 0.01!!!!
			if( abs(points[iii].x- TempPoint.x) <= 0.01 && abs(points[iii].y - TempPoint.y) <=0.01 )
			{
				selectedPointIndex = iii;
				printf("Found point in vector!!!\n");
				break;
			}
		}
 
 
		// upgrade vector at selectedPointIndex with FinalPoint when right mouse Release
		if ( selectedPointIndex > -1)
		{
			points[selectedPointIndex].x = FinalPoint.x;
			points[selectedPointIndex].y = FinalPoint.y;
 
		}
 
	  //
 
	  for (int i =0; i <= points.size() -1; i++)
      {
		  printf("OnePoint is %d  %d\n",points[i].x, points[i].y);
	  }
      printf("*****\n");
	  glutPostRedisplay();  // << has to be here to render the scene with the new data
}
 
 
 
 
void resize(int width, int height)
{
    glViewport( 0, 0, (GLint)width, (GLint)height );
 
    glMatrixMode( GL_PROJECTION);
    
	//gluOrtho2D(0.0, width,0.0, height);
 
	gluOrtho2D(0.0, width, height, 0.0);
 
    glMatrixMode(GL_MODELVIEW);
           
}
 
void main(int argc, char ** argv)
{
      glutInit(&argc, argv);
      glutInitDisplayMode(GLUT_SINGLE|GLUT_RGB);
      glutInitWindowPosition(50,100);
      glutInitWindowSize(512,512);
      glutCreateWindow("Drawing polyline with mouse interactive");
 
      init();
     
 
      //adding here the mouse processing callbacks
      glutMouseFunc(processMouse);
      glutDisplayFunc(lineSegment);
 
	  //glutMotionFunc(processMouseActiveMotion); 
 
 
 
      glutReshapeFunc(resize);
          
      
      //glutMotionFunc(processMouseActiveMotion);
      //glutPassiveMotionFunc(processMousePassiveMotion);
      //glutEntryFunc(processMouseEntry);
 
      glutMainLoop();
}
 

                                              

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Please do us a favor and correct the indention. Its so heard to read. At least in processMouse.
Then I'm gonna take a look later, when you posted the new version, cause I'm still at work

let me try to paste my code in here,not using attach code snippet. I hope indention is not damaged.

==================
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <math.h>
 
#include <GL/glut.h>
#include <vector>
 
struct point
{
        int x;
        int y;
};
      std::vector <point> points;
    point OnePoint;  
      point TempPoint;
      point FinalPoint;
      int selectedPointIndex = -1;
 
void init (void)
{
    glClearColor (1.0,1.0,1.0,0.0);
 
}
 
void lineSegment (void)
{
      glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
      glColor3f(1.0,0.0,0.0);          
      glBegin(GL_LINE_STRIP);
            for(int i =0; i < points.size();i++)
        {
                  glVertex2i(points[i].x, points[i].y);
        }
           
    glEnd();
    glFlush();
}
 
void processMouse(int button, int state, int x, int y)
{
      if (state == GLUT_DOWN)
      {
              if(button == GLUT_LEFT_BUTTON)
              {
                          // check to avoid duplicate elements in vector
                          bool _bfound = false;

                          for (int ii = 0; ii < points.size(); ii++)
                          {       
                                if( points[ii].x == x && points[ii].y == y)
                                {
                                      _bfound = true;
                                      printf("Duplicate element!!!\n");
                                      break;
                                }
                          }

                          if( _bfound == false)
                          {
                                OnePoint.x= x;
                                OnePoint.y= y;
                                points.push_back(OnePoint);
                          }  
              }
             
              if(button == GLUT_RIGHT_BUTTON)
              {
                    printf("Right click on mouse\n");

                    printf("PRESSMOUSE x is %d\n",x);
                    printf("PRESSMOUSE y is %d\n",y);
                    
                    TempPoint.x= x;
                    TempPoint.y= y;

              }
        }

        if( state == GLUT_UP)
        {
              if(button == GLUT_RIGHT_BUTTON)
              {
                    printf("RELEASEMOUSE x is %d\n",x);
                    printf("RELEASEMOUSE y is %d\n",y);

                    FinalPoint.x = x;
                    FinalPoint.y  = y;

              }
        }

        //check to see it TempPoint is in vector or not
            for (int iii = 0; iii < points.size(); iii++)
            {
                  // use approximately difference is 0.005. Need advise on difference value !!!
                  if( abs(points[iii].x- TempPoint.x) <= 0.005 && abs(points[iii].y - TempPoint.y) <=0.005 )
                  {
                        selectedPointIndex = iii;
                        printf("Found point in vector!!!\n");
                        break;
                  }
            }

            // upgrade vector at selectedPointIndex with FinalPoint when right mouse Release
            if ( selectedPointIndex > -1)
            {
                  points[selectedPointIndex].x = FinalPoint.x;
                  points[selectedPointIndex].y = FinalPoint.y;

            }

        //

        for (int i =0; i <= points.size() -1; i++)
      {
              printf("OnePoint is %d  %d\n",points[i].x, points[i].y);
        }
      printf("*****\n");
        glutPostRedisplay();  // << has to be here to render the scene with the new data
}

void resize(int width, int height)
{
    glViewport( 0, 0, (GLint)width, (GLint)height );
 
    glMatrixMode( GL_PROJECTION);
   
      //gluOrtho2D(0.0, width,0.0, height);
 
      gluOrtho2D(0.0, width, height, 0.0);

    glMatrixMode(GL_MODELVIEW);
           
}
 
void main(int argc, char ** argv)
{
      glutInit(&argc, argv);
      glutInitDisplayMode(GLUT_SINGLE|GLUT_RGB);
      glutInitWindowPosition(50,100);
      glutInitWindowSize(512,512);
      glutCreateWindow("Drawing polyline with mouse interactive");
 
      init();
     
 
      //adding here the mouse processing callbacks
      glutMouseFunc(processMouse);
      glutDisplayFunc(lineSegment);

        //glutMotionFunc(processMouseActiveMotion);

      glutReshapeFunc(resize);
               
      //glutMotionFunc(processMouseActiveMotion);
      //glutPassiveMotionFunc(processMousePassiveMotion);
      //glutEntryFunc(processMouseEntry);
 
      glutMainLoop();
}
 

you have to ckeck if any point was selected here

    if (state == GLUT_DOWN)
    {
        if(button == GLUT_RIGHT_BUTTON)
        {

                                              

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right now you do it, whenever processMouse is called, there is no "if" around it, you dont check the button or the state for this block:

        //check to see it TempPoint is in vector or not
            for (int iii = 0; iii < points.size(); iii++)
            {
                  // use approximately difference is 0.005. Need advise on difference value !!!
                  if( abs(points[iii].x- TempPoint.x) <= 0.005 && abs(points[iii].y - TempPoint.y) <=0.005 )
                  {
                        selectedPointIndex = iii;
                        printf("Found point in vector!!!\n");
                        break;
                  }
            }

i don't get your idea this time. Please elaborate for. Thanks.

and also
 // use approximately difference is 0.005. Need advise on difference value !!!

--> should I calculate percentage error and set it less than 5%?

   if (state == GLUT_DOWN)
    {
        if(button == GLUT_RIGHT_BUTTON)
        {
             for (int iii = 0; iii < points.size(); iii++)
            {
                  if( abs(points[iii].x- x) <= 3 && abs(points[iii].y - y) <= 3 )
                  {
                        selectedPointIndex = iii;
                        printf("Found point in vector!!!\n");
                        break;
                  }
            }
        }
    }

>> // use approximately difference is 0.005. Need advise on difference value !!!

where do you have that code from, you better take a bigger value like e points

Sorry, got no time to elabporate, gonna go to sleep now. Just give it a try, I'm sure you gonna make it ;)

good night. let me figure out what u mean. Thanks.

Hey vt, any luck so far?

hi ike,
 right now i am thinking about your advise
 " where do you have that code from, you better take a bigger value like e points"

 I think of using 5% as error percentage. For example let say x = 100. So when user click around between  95 and 105 , i can consider that like 100. How do u think?

>> right now i am thinking about your advise

Where excactly are you stuck?

not stuck. but try to find a good approach.

hi ike,
 I have last two questions for this program before i close it.  I want to make vertex is 3 pixel and line width is 2 pixel. by that way, user can click on vertex easier. Thanks a lot.

You can set it with:

glPointSize(3);
glLineWidth(2);

But then you have to render the points too in order to see the 3-pixel-points. Add the code below to line_segment:

    glBegin(GL_POINTS);
    for(int i =0; i < points.size();i++)
    {
        glVertex2i(points[i].x, points[i].y);
    }       
    glEnd();

                                              

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i declare
      glPointSize(3);
     glLineWidth(2);
 as global variables and this code

            glBegin(GL_POINTS);
    for(int ii =0; ii < points.size();ii++)
    {
        glVertex2i(points[ii].x, points[ii].y);
    }      
    glEnd();


 right now i have errors:

      C2373: 'glPointSize' : redefinition; different type modifiers
        c:\program files\microsoft visual studio\vc98\include\gl\gl.h(1351) : see declaration of 'glPointSize'
D:\OPENGL\Cpp2.cpp(21) : error C2501: 'glLineWidth' : missing storage-class or type specifiers
D:\OPENGL\Cpp2.cpp(21) : error C2373: 'glLineWidth' : redefinition; different type modifiers
        c:\program files\microsoft visual studio\vc98\include\gl\gl.h(1307) : see declaration of 'glLineWidth'
Error executing cl.exe.

You can put it into init:

void init (void)
{
    glClearColor (1.0,1.0,1.0,0.0);
    glPointSize(3);
    glLineWidth(2);
}
 

the rendering point-code has to be in line_segement:

void lineSegment (void)
{
    glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glColor3f(1.0,0.0,0.0);           
 
    // rendering the lines
    glBegin(GL_LINE_STRIP);
    for(int i =0; i < points.size();i++)
    {
        glVertex2i(points[i].x, points[i].y);
    }       
    glEnd();
 
    // rendering the points
    glBegin(GL_POINTS);
    for(int i =0; i < points.size();i++)
    {
        glVertex2i(points[i].x, points[i].y);
    }       
    glEnd();
 
    glFlush();
}
                                              

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