getting the position of a user mouse click in C & GLUT - c

Question

I would like to store the user's mouse click position on two variables
float x,y;
I'm using openGL with C. I already have a mouse function using glut, but when I try to print x and y, it gives me values like x = 134; y = 150, while my screen ortho is between 0 and 1.
I want to get the exact points to draw a point there.

Answer 1

you need to register a mouse callback function it has the following signature:
void glutMouseFunc(void (*func)(int button, int state,
int x, int y));
There's a tutorial that covers some basics here
Edit: If you want the position to be normalized (0.0 - 1.0) divide by the width and height:
float x1 = x /(float) width;
float y1 = y /(float) height;

Answer 2

this is a simple program i wrote hope it helps everyone like it helped me.
#include <cstdlib>
#include <GL/glut.h>
#include <iostream>
#include "Vec2.h"
Vec2 pos(0.0, 0.0);
Vec2 go(1.0, 1.0);
float mouseX;
float mouseY;
float angle = 0.0f;
void changeSize(int w, int h) {
// Prevent a divide by zero, when window is too short
// (you cant make a window of zero width).
if (h == 0)
h = 1;
float ratio = w * 1.0 / h;
// Use the Projection Matrix
glMatrixMode(GL_PROJECTION);
// Reset Matrix
glLoadIdentity();
// Set the viewport to be the entire window
glViewport(0, 0, w, h);
// Set the correct perspective.
gluPerspective(45.0f, ratio, 0.1f, 100.0f);
// Get Back to the Modelview
glMatrixMode(GL_MODELVIEW);
}
void renderScene(void) {
// Clear Color and Depth Buffers
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
// Reset transformations
glLoadIdentity();
// Set the camera
gluLookAt( 0.0f, 0.0f, 10.0f,
0.0f, 0.0f, 0.0f,
0.0f, 1.0f, 0.0f);
glPushMatrix();
glRotatef(angle, 0.0f, 0.0f, 1.0f);
glTranslatef(0.0, 0.0, 0.0);
glBegin(GL_LINE_LOOP);
glVertex3f( 0.0f, 2.0f, 0.0f);
glVertex3f( -1.0f, -1.0f, 0.0f);
glVertex3f( 1.0f, -1.0f, 0.0f);
glEnd();
glPopMatrix();
//angle+=0.01f;
glutSwapBuffers();
}
void mouseMove(int x, int y)
{
mouseX = -1.0 + 2.0 * x / 320 ;
mouseY = 1.0 - 2.0 * y / 320 ;
angle = 90 + atan2(pos.y-mouseY, pos.x-mouseX) * 180 / 3.1415926;
//std::cout << mouseX << ", " << mouseY << std::endl;
//std::cout << x << ", " << y << std::endl;
std::cout << angle << std::endl;
}
int main(int argc, char **argv) {
// init GLUT and create window
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA);
glutInitWindowPosition(100,100);
glutInitWindowSize(320,320);
glutCreateWindow("Lighthouse3D- GLUT Tutorial");
// register callbacks
glutDisplayFunc(renderScene);
glutReshapeFunc(changeSize);
glutIdleFunc(renderScene);
glutMotionFunc(mouseMove);
// enter GLUT event processing cycle
glutMainLoop();
return 1;
}