Finish drawing a polygon by right-clicking, but displaying a menu instead - c++

Question

I am writing a program that will continuously draw a polygon until the user right-clicks. The user can only draw if and only if the user makes a selection in the menu, if the user does not make a selection in the menu, the program will not draw. Up to now, my program has successfully drawn a polygon with the mouse, but the problem is that when I right-click to complete, the program pops up the menu instead of completing the polygon. Now how can I right-click to be able to complete the polygon, here's my program:
const int MAX = 100;
float mouseX, mouseY, ListX[MAX], ListY[MAX];
int numPoints = 0, closed = 0, shape = 0;
void mouse(int button, int state, int x, int y)
{
mouseX = x;
mouseY = y;
if (button == GLUT_LEFT_BUTTON && state == GLUT_DOWN)
{
if (closed || numPoints >= MAX - 1)
numPoints = 0;
closed = 0;
ListX[numPoints] = mouseX;
ListY[numPoints] = mouseY;
numPoints++;
}
if (button == GLUT_RIGHT_BUTTON && state == GLUT_DOWN)
closed = 1;
}
void motion(int x, int y)
{
mouseX = x;
mouseY = y;
glutPostRedisplay();
}
void display()
{
glClear(GL_COLOR_BUFFER_BIT);
if (shape == 1)
{
if (numPoints)
{
glBegin(GL_LINE_STRIP);
for (int i = 0; i < numPoints; ++i)
glVertex2f(ListX[i], ListY[i]);
if (closed)
glVertex2f(ListX[0], ListY[0]);
else
glVertex2f(mouseX, mouseY);
glEnd();
}
}
glFlush();
}
void menu(int choice)
{
switch (choice)
{
case 1:
shape = 1;
break;
}
}
int main(int argc, char** argv)
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
glutInitWindowSize(640, 480);
glutInitWindowPosition(100, 100);
glutCreateWindow("");
gluOrtho2D(0, 640, 480, 0);
glutCreateMenu(menu);
glutAddMenuEntry("Polygon", 1);
glutAttachMenu(GLUT_RIGHT_BUTTON);
glutDisplayFunc(display);
glutMouseFunc(mouse);
glutPassiveMotionFunc(motion);
glutMainLoop();
}
Edit: Thanks to genpfault, I finished the polygon by right-clicking but I don't know how to reattach it so I can re-open the menu.
...
void display()
{
glClear(GL_COLOR_BUFFER_BIT);
if (shape == 1)
{
glutDetachMenu(GLUT_RIGHT_BUTTON); // Add this
...
}
glFlush();
}
void menu(int choice)
{
switch (choice)
{
case 1:
shape = 1;
break;
}
}
int main(int argc, char** argv)
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
glutInitWindowSize(640, 480);
glutInitWindowPosition(100, 100);
glutCreateWindow("");
gluOrtho2D(0, 640, 480, 0);
glutCreateMenu(menu);
glutAddMenuEntry("Polygon", 1);
glutAttachMenu(GLUT_RIGHT_BUTTON);
glutDisplayFunc(display);
glutMouseFunc(mouse);
glutPassiveMotionFunc(mouse_move);
glutMainLoop();
}

Answer 1

Capture the return-value from glutCreateMenu(), that's the handle for the new menu.
Detach the menu in the menu callback via glutDetachMenu() and set a bool indicating you're in "add points" mode.
If you're in "add points" mode and detect a right-click, set the current menu to the menu handle from #1 via glutSetMenu(), then re-attach the menu with glutAttachMenu(). Reset the "add points" bool to false.
All together:
#include <GL/glut.h>
const int MAX = 100;
float mouseX, mouseY, ListX[MAX], ListY[MAX];
int numPoints = 0, closed = 0, shape = 0;
int hMenu = 0;
bool addingPoints = false;
void mouse(int button, int state, int x, int y)
{
mouseX = x;
mouseY = y;
if( addingPoints )
{
if( button == GLUT_LEFT_BUTTON && state == GLUT_DOWN )
{
if (closed || numPoints >= MAX - 1)
numPoints = 0;
closed = 0;
ListX[numPoints] = mouseX;
ListY[numPoints] = mouseY;
numPoints++;
}
if( button == GLUT_RIGHT_BUTTON && state == GLUT_DOWN )
{
closed = 1;
addingPoints = false;
glutSetMenu(hMenu);
glutAttachMenu(GLUT_RIGHT_BUTTON);
}
}
}
void motion(int x, int y)
{
mouseX = x;
mouseY = y;
glutPostRedisplay();
}
void display()
{
glClear(GL_COLOR_BUFFER_BIT);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0, 640, 480, 0, -1, 1);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
if (shape == 1)
{
if (numPoints)
{
glBegin(GL_LINE_STRIP);
for (int i = 0; i < numPoints; ++i)
glVertex2f(ListX[i], ListY[i]);
if (closed)
glVertex2f(ListX[0], ListY[0]);
else
glVertex2f(mouseX, mouseY);
glEnd();
}
}
glutSwapBuffers();
}
void menu(int choice)
{
switch (choice)
{
case 1:
numPoints = 0;
shape = 1;
addingPoints = true;
glutDetachMenu(GLUT_RIGHT_BUTTON);
break;
}
}
int main(int argc, char** argv)
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB);
glutInitWindowSize(640, 480);
glutCreateWindow("");
hMenu = glutCreateMenu(menu);
glutSetMenu(hMenu);
glutAddMenuEntry("Polygon", 1);
glutAttachMenu(GLUT_RIGHT_BUTTON);
glutDisplayFunc(display);
glutMouseFunc(mouse);
glutPassiveMotionFunc(motion);
glutMainLoop();
}