Getting the user's mouse click position in C & GLUT

Question

I would like to keep the user's click position on two variables

float x,y; 

I am using openGL with C I already have a mouse function using oversupply, but when I try to print x and y, it gives me values ​​like x = 134; y = 150 x = 134; y = 150 , while my screen is in the range of 0 to 1.

I want to get exact points to draw a point there.

Answer 1

you need to register the mouse callback function, it has the following signature:

 void glutMouseFunc(void (*func)(int button, int state, int x, int y)); 

Here is a tutorial that covers some basics here

Edit: If you want the position normalization (0.0 - 1.0) to divide by width and height:

 float x1 = x /(float) width; float y1 = y /(float) height; 

Answer 2

This is a simple program that I wrote, I hope that it helps everyone who helped.

 #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; }