How to get smooth input for game in glut C++? - c++

Question

how do I get my C++ glut project to have smooth input?
the only way I could get input was with a slight delay, which is annoying. I am new to C++ glut so pls help me.
#include <windows.h>
#include <GL/glut.h>
#include <GL/glu.h>
#include <stdio.h>
#include <iostream>
GLboolean upPressed = false;
using namespace std;
void display();
void reshape(int,int);
void timer(int);
void keyboard_callback(int, int, int);
void SpecialKeysUp(int, int, int);
void update();
void init()
{
glClearColor(0.0, 0.0, 0.0, 0.0);
}
int main(int argc, char**argv)
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
glutInitWindowPosition(200, 100);
glutInitWindowSize(500, 500);
glutCreateWindow("window");
glutSpecialFunc(keyboard_callback);
glutDisplayFunc(display);
glutReshapeFunc(reshape);
glutTimerFunc(0,timer,0);
glutSpecialUpFunc(SpecialKeysUp);
glutIdleFunc(update);
init();
glutMainLoop();
}
// sy is the first squares y position. no x value needed since the x value is static.
// also note that the "s" in sy stands for square, squarey_position
float x_position = 0.0;
float sy_position = -4.0;
int state = 1;
char input;
void display()
{
glClear(GL_COLOR_BUFFER_BIT);
glLoadIdentity();
glBegin(GL_QUADS);
glColor3f(1.0,0.0,0.0);
glVertex2f(x_position,1.0);
glVertex2f(x_position,-1.0);
glVertex2f(x_position+2.0,-1.0);
glVertex2f(x_position+2.0,1.0);
glColor3f(1.0,0.0,0.0);
glVertex2f(-8.0,sy_position);
glVertex2f(-9.0,sy_position);
glVertex2f(-9.0,sy_position+8.0);
glVertex2f(-8.0,sy_position+8.0);
glEnd();
glutSwapBuffers();
}
void reshape(int w,int h)
{
glViewport(0,0,(GLsizei)w,(GLsizei)h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluOrtho2D(-10, 10, -10, 10);
glMatrixMode(GL_MODELVIEW);
}
void timer(int)
{
glutPostRedisplay();
glutTimerFunc(1000/60,timer,0);
switch(state)
{
case 1:
if(x_position<8)
x_position+=0.15;
else
state = -1;
break;
case -1:
if(x_position>-10)
x_position-=0.15;
else
state=1;
break;
}
}
void keyboard_callback(int key, int, int)
{
if(GLUT_KEY_UP == key)
upPressed = true;
}
void SpecialKeysUp(int key, int, int)
{
if(GLUT_KEY_UP == key)
upPressed = false;
}
void update()
{
// glutPostRedisplay();
// glutTimerFunc(1000/60,update,0);
if(upPressed)
sy_position+=0.15;
}
It is a ping pong game and currently the ball is working fine, however I am trying to get smooth input for the rectangle but the only way I could was with input delay.
I am new to glut C++ so pls help me

Answer 1

Actually I figured out how to do it. The glutTimerFunc updates and resets every 1000/60 milliseconds so valuing a bool at "true" whilst the up key is pressed(with GLUT_KEY_UP) and then valuing a bool at "false" when the key is not pressed(with the SpecialUpFunc) makes for smoother input since the update function resets must faster than just holding the key down.