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I have a code to find the cell mouse clicked in chess board then a 2D Triangle shape go to the cell position, Now I want to change 2D Triangle to 3D cube but I don't know how to do that.

This my code 

#include <string>
#include <stdlib.h>
#ifdef __APPLE__
#include <OpenGL/OpenGL.h>
#include <GLUT/glut.h>
#else
#include <GL/glut.h>
#endif
#include <iostream>
using namespace std;

void init()
{
    glClearColor (1.0, 0.0, 1.0, 0.0);
    glShadeModel (GL_FLAT);
}
const int scl = 80 ;
const int STEP_SIZE = 80;
const int WIN_WIDTH = 800;
const int WIN_HEIGHT = 800;
int LeftRight = 0 ;
int UpDown = 0;

void moveRight()
{
    LeftRight+=STEP_SIZE;
}
void moveLeft()
{
    LeftRight-=STEP_SIZE;
}
void moveUp()
{
    UpDown+=STEP_SIZE;
}
void moveDown()
{
    UpDown-=STEP_SIZE;
}
void DrawBoard()
{
    int x , y , color = 0;
    glClear (GL_COLOR_BUFFER_BIT);
    for(x=1; x<=8; x++)
    {
        if(color==0)
            glColor3f (1.0, 0.0, 0.0), color++;

        else
            glColor3f (1.0, 1.0, 1.0),color=0;

        for(y=1; y<=8; y++)
        {
            if(color==0)
                glColor3f (0.0, 0.0, 0.0),color++;
            else
                glColor3f (1.0, 1.0, 1.0),color=0;

            glBegin(GL_QUADS);
            glVertex2f(scl+scl*x, scl+scl*y);
            glVertex2f(scl*x, scl+scl*y);
            glVertex2f(scl*x, scl*y);
            glVertex2f(scl+scl*x, scl*y);
            glEnd();
        }
    }
  // This is the Triangle that will change to cube 
    glBegin(GL_QUADS);
    glColor3f (1.0, 0.5, 0.0);
    glVertex2f(90+LeftRight,100+UpDown);
    glVertex2f(90+LeftRight,100+UpDown);
    glVertex2f(120+LeftRight,140+UpDown);
    glVertex2f(150+LeftRight,100+UpDown);
    glEnd();
//--------------------------------------
    glFlush ();


}
int mouse_x = -1  ;
int mouse_y = -1 ;
int object_x = -1  ;
int object_y = -1 ;

void moveObjectToFrom()
{
    if (mouse_x > 8 || mouse_x < 1 || mouse_y > 8 || mouse_y < 1 )
        return ;
    if(object_x > mouse_x )
    {
        object_x-- ;
        moveUp();
    }
    if(object_x < mouse_x )
    {
        object_x++;
        moveDown();

    }
    if(object_y > mouse_y )
    {
        object_y-- ;
        moveLeft();

    }
    if(object_y < mouse_y)
    {
        object_y++ ;
        moveRight();
    }

}

void mouseClicks( int button , int key, int x, int y )
{
    // this variables related to chessboard
    mouse_x =  y / scl ;
    mouse_y = 9 - (WIN_HEIGHT - x)/scl ;
    object_x = 9 - (100 + UpDown)/ scl  ;
    object_y = 9 - (WIN_HEIGHT - (LeftRight+90))/scl ;

    if (button !=0 || mouse_x > 8 || mouse_x < 1 || mouse_y > 8 || mouse_y < 1 )
        return ;

    glutPostRedisplay();
}


void reshape (int w, int h)
{
    glViewport (0, 0, (GLsizei) w, (GLsizei) h);
    glMatrixMode (GL_PROJECTION);
    glLoadIdentity ();
    gluOrtho2D (0.0, (GLdouble) w, 0.0, (GLdouble) h);
}

void update(int value)
{

    moveObjectToFrom();
    glutTimerFunc(50, update, 0);
    glutPostRedisplay();
}

int main(int argc, char** argv)
{
    glutInit(&argc, argv);
    //  glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);
    glEnable(GL_DEPTH_TEST);
    glutInitWindowSize (WIN_WIDTH, WIN_HEIGHT);
    glutInitWindowPosition (100,100);
    glutCreateWindow (argv[0]);
    glutTimerFunc(25, update, 0);
    glutMouseFunc(mouseClicks);
    init ();
    glutDisplayFunc(DrawBoard);
    glutReshapeFunc(reshape);
    glutMainLoop();
    return 0;
}
genpfault
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Amr
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  • So you want to map a mouse click in a 3d scene? If so, you can take a look at https://www.opengl.org/discussion_boards/showthread.php/175699-How-to-click-on-3D-objects-with-mouse and see if one of those answers helps you. – Aumnayan Apr 25 '17 at 18:23

1 Answers1

1

Your main problem is that your GL_PROJECTION is set to gluOrtho2D so when you render axis align cube it will always produce just square. To remedy this you should use gluProjection instead. But that will give you view centered around 0.0,0.0 instead of your current screen center coordinate (0.5*w,0.5*h) so you need also translate the GL_MODELVIEW by it.

Here example how to do this:

Now to render a cube you can do this:

void render_cube()
    {
    const GLfloat a=20.0;   // cube half size
    const GLfloat pos[]=    // glVertex cube centered at (0,0,0) of size 2*a
        {
    //   x  y  z
        -a,+a,-a,
        +a,+a,-a,
        +a,-a,-a,
        -a,-a,-a,

        -a,-a,+a,
        +a,-a,+a,
        +a,+a,+a,
        -a,+a,+a,

        -a,-a,-a,
        +a,-a,-a,
        +a,-a,+a,
        -a,-a,+a,

        +a,-a,-a,
        +a,+a,-a,
        +a,+a,+a,
        +a,-a,+a,

        +a,+a,-a,
        -a,+a,-a,
        -a,+a,+a,
        +a,+a,+a,

        -a,+a,-a,
        -a,-a,-a,
        -a,-a,+a,
        -a,+a,+a,
        };
    const GLfloat col[]=
        {
    //  r   g   b    
        1.0,0.0,0.0,
        1.0,0.0,0.0,
        1.0,0.0,0.0,
        1.0,0.0,0.0,

        1.0,1.0,0.0,
        1.0,1.0,0.0,
        1.0,1.0,0.0,
        1.0,1.0,0.0,

        0.0,1.0,0.0,
        0.0,1.0,0.0,
        0.0,1.0,0.0,
        0.0,1.0,0.0,

        0.0,1.0,1.0,
        0.0,1.0,1.0,
        0.0,1.0,1.0,
        0.0,1.0,1.0,

        0.0,0.0,1.0,
        0.0,0.0,1.0,
        0.0,0.0,1.0,
        0.0,0.0,1.0,

        1.0,1.0,1.0,
        1.0,1.0,1.0,
        1.0,1.0,1.0,
        1.0,1.0,1.0,
        };
    const GLfloat nor[]=    // glNormal
        {
    //   nx   ny   nz
         0.0, 0.0,-1.0,
         0.0, 0.0,-1.0,
         0.0, 0.0,-1.0,
         0.0, 0.0,-1.0,

         0.0, 0.0,+1.0,
         0.0, 0.0,+1.0,
         0.0, 0.0,+1.0,
         0.0, 0.0,+1.0,

         0.0,-1.0, 0.0,
         0.0,-1.0, 0.0,
         0.0,-1.0, 0.0,
         0.0,-1.0, 0.0,

        +1.0, 0.0, 0.0,
        +1.0, 0.0, 0.0,
        +1.0, 0.0, 0.0,
        +1.0, 0.0, 0.0,

         0.0,+1.0, 0.0,
         0.0,+1.0, 0.0,
         0.0,+1.0, 0.0,
         0.0,+1.0, 0.0,

        -1.0, 0.0, 0.0,
        -1.0, 0.0, 0.0,
        -1.0, 0.0, 0.0,
        -1.0, 0.0, 0.0,
        };
    int i,i3;
    glBegin(GL_QUADS);
    for (i=0,i3=0;i<24;i++,i3+=3)
        {
        glColor3fv (col+i3);
        glNormal3fv(nor+i3);
        glVertex3fv(pos+i3);
        }
    glEnd();
    }

which is supposed to render like this:

glEnable(GL_LIGHTING);
glEnable(GL_LIGHT0);
glEnable(GL_COLOR_MATERIAL);
glEnable(GL_CULL_FACE);
glFrontFace(GL_CCW);
render_cube();

just set the a constant to what ever you need and translate modelview to its placement position ...

here preview:

cube

Each side has its own color for debug purposes ... Look here for 3D view example:

[Edit1] I tweaked your code a bit

there were some inconsistencies in polygon winding. Try to swap your functions with these (they worked for me) and leave the rest of your code as is:

//---------------------------------------------------------------------------
void render_cube(GLfloat a) // cube half size
    {
    GLfloat pos[]=  // glVertex
        {
    //   x  y  z
        -a,+a,-a,
        +a,+a,-a,
        +a,-a,-a,
        -a,-a,-a,

        -a,-a,+a,
        +a,-a,+a,
        +a,+a,+a,
        -a,+a,+a,

        -a,-a,-a,
        +a,-a,-a,
        +a,-a,+a,
        -a,-a,+a,

        +a,-a,-a,
        +a,+a,-a,
        +a,+a,+a,
        +a,-a,+a,

        +a,+a,-a,
        -a,+a,-a,
        -a,+a,+a,
        +a,+a,+a,

        -a,+a,-a,
        -a,-a,-a,
        -a,-a,+a,
        -a,+a,+a,
        };
    const GLfloat col[]=    // glColor
        {
    //  r   g   b
        1.0,0.0,0.0,
        1.0,0.0,0.0,
        1.0,0.0,0.0,
        1.0,0.0,0.0,

        1.0,1.0,0.0,
        1.0,1.0,0.0,
        1.0,1.0,0.0,
        1.0,1.0,0.0,

        0.0,1.0,0.0,
        0.0,1.0,0.0,
        0.0,1.0,0.0,
        0.0,1.0,0.0,

        0.0,1.0,1.0,
        0.0,1.0,1.0,
        0.0,1.0,1.0,
        0.0,1.0,1.0,

        0.0,0.0,1.0,
        0.0,0.0,1.0,
        0.0,0.0,1.0,
        0.0,0.0,1.0,

        1.0,1.0,1.0,
        1.0,1.0,1.0,
        1.0,1.0,1.0,
        1.0,1.0,1.0,
        };
    const GLfloat nor[]=    // glNormal
        {
    //   nx   ny   nz
         0.0, 0.0,-1.0,
         0.0, 0.0,-1.0,
         0.0, 0.0,-1.0,
         0.0, 0.0,-1.0,

         0.0, 0.0,+1.0,
         0.0, 0.0,+1.0,
         0.0, 0.0,+1.0,
         0.0, 0.0,+1.0,

         0.0,-1.0, 0.0,
         0.0,-1.0, 0.0,
         0.0,-1.0, 0.0,
         0.0,-1.0, 0.0,

        +1.0, 0.0, 0.0,
        +1.0, 0.0, 0.0,
        +1.0, 0.0, 0.0,
        +1.0, 0.0, 0.0,

         0.0,+1.0, 0.0,
         0.0,+1.0, 0.0,
         0.0,+1.0, 0.0,
         0.0,+1.0, 0.0,

        -1.0, 0.0, 0.0,
        -1.0, 0.0, 0.0,
        -1.0, 0.0, 0.0,
        -1.0, 0.0, 0.0,
        };
    int i,i3;
    glBegin(GL_QUADS);
    for (i=0,i3=0;i<24;i++,i3+=3)
        {
        glColor3fv (col+i3);
        glNormal3fv(nor+i3);
        glVertex3fv(pos+i3);
        }
    glEnd();
    }
//---------------------------------------------------------------------------
void init()
    {
    glClearColor(1.0, 0.0, 1.0, 0.0);
    glShadeModel(GL_FLAT);
    glEnable(GL_DEPTH_TEST);
    glEnable(GL_LIGHTING);
    glEnable(GL_LIGHT0);
    glEnable(GL_COLOR_MATERIAL);
    glEnable(GL_CULL_FACE);
    glFrontFace(GL_CCW);
    }
//---------------------------------------------------------------------------
const int scl = 80 ;
int LeftRight = 0 ;
int UpDown = 0;
void DrawBoard()
    {
    int x , y , color = 0;
    glClear (GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);  // do not forget also to clear depth buffer
    for(x=1;x<=8;x++)
        {
        if (color) glColor3f (0.0, 0.0, 0.0);           // I like this a bit better then your approach
        else       glColor3f (1.0, 1.0, 1.0); color^=1;
        for(y=1; y<=8; y++)
            {
            if (color) glColor3f (0.0, 0.0, 0.0);
            else       glColor3f (1.0, 1.0, 1.0); color^=1;
            glBegin(GL_QUADS);
            glNormal3f(0.0,0.0,+1.0);
            glVertex3f(scl+scl*x, scl+scl*y,0.0);
            glVertex3f(scl*x, scl+scl*y,0.0);
            glVertex3f(scl*x, scl*y,0.0);
            glVertex3f(scl+scl*x, scl*y,0.0);
            glEnd();
            }
        }
    // your triangle just above cube (and reversed order to match the rest of rendering)
    glBegin(GL_QUADS);
    glColor3f (1.0, 0.5, 0.0);
    glNormal3f(0.0,0.0,+1.0);
    glVertex3f(150+LeftRight,100+UpDown,scl+1.0);
    glVertex3f(120+LeftRight,140+UpDown,scl+1.0);
    glVertex3f( 90+LeftRight,100+UpDown,scl+1.0);
    glVertex3f( 90+LeftRight,100+UpDown,scl+1.0);
    glEnd();
    // cube
    glMatrixMode(GL_MODELVIEW);
    glPushMatrix();                             // remember modelview
    glTranslatef(1.5*scl+LeftRight,1.5*scl+UpDown,+0.5*scl);    // set cube position
    render_cube(0.5*scl);
    glPopMatrix();                              // restore modelview
    glFlush();
    }
//---------------------------------------------------------------------------
void reshape (int w, int h)
    {
    glViewport (0, 0, (GLsizei) w, (GLsizei) h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluPerspective(60,float(w)/float(h),10.0,10000.0);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    glTranslatef(-w/2,-h/2,-1000.0);
    }
//---------------------------------------------------------------------------

Using 800x800 window the result should look like this:

preview

btw. these includes are obsolete:

#include <string>
#include <stdlib.h>
#include <iostream>
using namespace std;

as you are not using anything from them in your code.

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Spektre
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  • I tried to do that but nothing ,I'm just a beginner so would you help me to merge two codes please !? – Amr Apr 27 '17 at 04:56
  • @Amr 1. if your problem is not solved yet then do not accept it as answer (because accept flags that your problem is solved which means there is very low chance other people will add new answers) up vote is ok. 2. you first need to change the projection matrix so it has perspective projection and you see the view as you did with the ortho. So you need to experiment with `znear,zfar` checker board placement (`vertex3f` z coordinate) and place the board in depth so there is still place for the cube before it. only if that works you can continue. – Spektre Apr 27 '17 at 07:25
  • @Amr do not forget to either translate modelview or center your mesh around `(0,0)` otherwise you will see just quater of your board. 3. did you change the `a` constant of cube size so it actually fit inside view? I expect the size would be half of checker board square. 4. see the links in my answer the settings of yours should be similar if not the same. 5. what do you mean by `but nothing`? you did not see anything or just the cube was not rendered or what? would be nice to see code after your update. The important stuff is render loop and settings of camera – Spektre Apr 27 '17 at 07:30
  • @Amr I try to use your code see [edit1] for the changes you need to do to get this work – Spektre Apr 27 '17 at 09:05