Trying to make the mouse move...

[Codeboy]

I have got some code from this website and messed around with it. I am trying to make the mouse move right 1 coordinate when you press the 'a' key. It is not doing what its supposed to do. I don't know what is wrong.
/* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above notice and this permission notice shall be included in all copies
* or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
/* File for "Basic Shapes" lesson of the OpenGL tutorial on
* www.videotutorialsrock.com
*/



#include <iostream>
#include <stdlib.h> //Needed for "exit" function

//Include OpenGL header files, so that we can use OpenGL
#ifdef __APPLE__
#include <OpenGL/OpenGL.h>
#include <GLUT/glut.h>
#else
#include <GL/glut.h>
#endif

using namespace std;

//Called when a key is pressed
void handleKeypress(unsigned char key, //The key that was pressed
int x, int y) { //The current mouse coordinates
switch (key) {
case 27: //Escape key
exit(0);//Exit the program
}
if (key == 'a')
{
x++;
}
}

//Initializes 3D rendering
void initRendering() {
//Makes 3D drawing work when something is in front of something else
glEnable(GL_DEPTH_TEST);
}

//Called when the window is resized
void handleResize(int w, int h) {
//Tell OpenGL how to convert from coordinates to pixel values
glViewport(0, 0, w, h);

glMatrixMode(GL_PROJECTION); //Switch to setting the camera perspective

//Set the camera perspective
glLoadIdentity(); //Reset the camera
gluPerspective(45.0, //The camera angle
(double)w / (double)h, //The width-to-height ratio
1.0, //The near z clipping coordinate
200.0); //The far z clipping coordinate
}

//Draws the 3D scene
void drawScene() {
//Clear information from last draw
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

glMatrixMode(GL_MODELVIEW); //Switch to the drawing perspective
glLoadIdentity(); //Reset the drawing perspective

glBegin(GL_QUADS); //Begin quadrilateral coordinates

//Trapezoid
glVertex3f(-0.7f, -1.5f, -5.0f);
glVertex3f(0.7f, -1.5f, -5.0f);
glVertex3f(0.4f, -0.5f, -5.0f);
glVertex3f(-0.4f, -0.5f, -5.0f);

glEnd(); //End quadrilateral coordinates

glutSwapBuffers(); //Send the 3D scene to the screen
}

int main(int argc, char** argv) {
//Initialize GLUT
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
glutInitWindowSize(400, 400); //Set the window size

//Create the window
glutCreateWindow("Basic Shapes - videotutorialsrock.com");
initRendering(); //Initialize rendering

//Set handler functions for drawing, keypresses, and window resizes
glutDisplayFunc(drawScene);
glutKeyboardFunc(handleKeypress);
glutReshapeFunc(handleResize);

glutMainLoop(); //Start the main loop. glutMainLoop doesn't return.
return 0; //This line is never reached
}

[firedraco]

It's because you are passing copies of the variables to your handleKeypress function, so when you modify x, you are modifying the copy, which is then deleted. If you want to modify the original x, you will have to pass by reference. Also, even then, depending on what happens to the data, glutKeyboardFunc() may be passing a copy too, which means you can't edit the mouse position through that function.

[Codeboy]

Thanks! I will fix it now based on your information. Thanks again!!!