Using glutKeyboardFunc in a very simple exemple, i could get it to work very easily :
void special(int key, int x, int y) {
printf("key %d\n", key);
}
void keyboard(unsigned char key, int x, int y) {
printf("key %d\n", key);
}
void display() {}
int main(int argc, char** argv) {
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE | GLUT_DEPTH);
glutInitWindowSize(640, 480);
glutCreateWindow("GLUT Program");
glutDisplayFunc(display);
glutKeyboardFunc(keyboard);
glutSpecialFunc(special);
glutMainLoop();
return EXIT_SUCCESS;
}
but using it with a very complex display function, the keyboard routine is never called, I am not sure about the part that prevents this call from working so i am just asking here for ideas about what could be the cause, i can't really post the code because that would be the entire project... i am using freeglut with an opengl context and glm for math computation.
Nevertheless here is the new call :
static void loop_function() {
glutSetWindow(win);
Scene::unique_scene->mainloop();
}
I am a bit lost about what to do to find the error, if someone could enlighten me i would be grateful.
Having an infinite loop in the glutDisplayFunc is not the way to go, it is called automatically at the end of the glutKeyboardFunc if you added the call
glutPostRedisplay();
Related
A program crashes if I try to use ifstream while having OpenGL/freeglut. My code:
#include <fstream>
#include <windows.h>
#include <GL/freeglut.h>
double x, y;
std::ifstream read("coordinates.txt");
void display() {
glBegin(GL_LINE_STRIP);
while (read >> x) //Crashes here
{
read >> y;
glVertex2d(x, y);
}
glEnd();
glFlush();
}
void key(unsigned char mychar, int x, int y) {
if (mychar == 27) {
exit(0);
}
}
void initialize()
{
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluOrtho2D(-27, 27, -27, 27);
}
int main(int argc, char **argv) {
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_RGB | GLUT_SINGLE);
glutInitWindowSize(1920, 1080);
glutInitWindowPosition(0, 0);
glutCreateWindow("Lorenz Attractor");
initialize();
glutDisplayFunc(display);
glutKeyboardFunc(key);
glColor3d(0, 0, 1);
glutFullScreen();
glutMainLoopEvent();
Sleep(60000);
}
coordinates.txt:
1.1 1.03
2.5 2
3 5.3
I don't even need to include freeglut, I checked out an older project that was working perfectly before and now it crashes as well. Using Code::Blocks with MinGW. Why would this happen? Thanks!
display will be called more than one time. It's called whenever the display needs to be redrawn, such as when the window comes into view, another window is moved over top of it, the window is resized, etc.
display reads a file. Well, after the first time it reads the file, the file will be empty. After all, you opened the file in a global variable (FYI: never do that), and you kept reading until the file was empty.
Don't read files while you're drawing. Read the file into a data structure (say, a vector<float>). Do that before the rendering loop. Then, use the data structure to draw from.
I've tried some OpenGL C++ training.
But I have a logic problem, how can I update my OpenGL Windows window.
It should draw text one, then delay 1-2sec, then draw text 2, but now it draws same time. Can anyone help or give a hint.
void text () {
wait(1);
Sleep(1000);
std::string text_one;
text_one = "Text 1";
glColor3f(1,01, 0);
drawText(text_one.data(), text_one.size(), 050, 150);
glutPostRedisplay();
wait (1)
std::string text_two;
text_two = "Text 2";
glColor3f(1,0, 0);
drawText(text_two.data(), text_two.size(), 250, 150);
}
and here the main
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(640,640);
glutCreateWindow("Test 001");
// register callbacks
glutDisplayFunc(renderScene);
glutIdleFunc(text);
// enter GLUT event processing cycle
glutMainLoop();
return 1;
}
You should render in renderScene callback. It will be called automatically in you screen refresh rate. If you want some delay you need to implement it inside this callback (functions called from this callback).
So basically you need to re-render everything every 1/60 second.
If you want to implement easy delay you can do something like this:
void renderScene() {
time += deltaTime;
RenderText1();
if (time > delayTime)
RenderText2();
glutSwapBuffers();
}
For example, in my "test.txt" file
2 3
2 4
2 5
When I show in my OpenGL/C++ ( I'm using graph to represent it )
so when I go to my "test.txt" file and change some value and want to see
the new graph with new data without stop and recompile back.
isn't any way to refresh it?
NOTE: glutPostRedisplay() not working.
Thanks
void drawScene(void)
{
readFile(inFile);
glClear(GL_COLOR_BUFFER_BIT);
glColor3f(0.0,0.0,0.0);
histogram();
linestrip();
piechart2012();
piechart2013();
glFlush();
//readFile(inFile);
}
int main( int argc, char **argv )
{
glutInit (&argc, argv); /* Initialise OpenGL */
glutInitDisplayMode(GLUT_SINGLE | GLUT_RGBA);
glutInitWindowSize(800,600);
glutInitWindowPosition(100,100);
printInteraction();
glutCreateWindow ( "square.cpp" ); /* Create the window */
glutDisplayFunc (drawScene); /* Register the "display" function */
glutReshapeFunc(resize);
glutKeyboardFunc(keyInput);
setup();
glutMainLoop(); /* Enter the OpenGL main loop */
return 0;
}
I have created a simple Visual Studio Express 2010 C++ project using GLUT and OpenGL,
it compiles and runs ok, except that the window it creates receives no events..
the close/minimize buttons don't do anything (not even mouseover) no context menu on the task bar on right click, and the window doesn't come to the foreground when clicked if partially covered.
The project is set up as a console application, I can close the program by closing the console.
I have this in main:
int main(int argc, char** argv)
{
glutInit(&argc, argv);
glutInitWindowSize(window_width, window_height);
glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
glutCreateWindow("MyApp");
glutIdleFunc(main_loop_function);
GLenum err = glewInit();
if (GLEW_OK != err)
{
/* Problem: glewInit failed, something is seriously wrong. */
fprintf(stderr, "Error: %s\n", glewGetErrorString(err));
}
if (GLEW_VERSION_1_3)
{
fprintf(stdout, "OpenGL 1.3 is supported \n");
}
fprintf(stdout, "Status: Using GLEW %s\n", glewGetString(GLEW_VERSION));
GL_Setup(window_width, window_height);
glutMainLoop();
}
You miss a display callback. Could you try:
void display();
int main(int argc, char** argv)
{
glutInit(&argc, argv);
glutInitWindowSize(window_width, window_height);
glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
glutCreateWindow("MyApp");
/// glutIdleFunc(main_loop_function);
glutDisplayFunc(display);
// ...
glutMainLoop();
}
void display(){
glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
glutSwapBuffers();
}
Also, your idle function seems bad, if you effectively loop inside that function. Glut is callback oriented. You don't need to create a loop, but rather rely on idle, mouse, keyboard, display and resize callbacks. If you don't do so, you are going to miss window manager events.
EDIT:
If you want to create an animation, you could use:
glutIdleFunc(idleFunc);
void idleFunc(){
glutPostRedisplay();
}
I have the following program
void allocVars(){
m_window = new GLWindow(); //glGenTexture() is called //CRASH!
m_window->Init(m_cam.w, m_cam.h, "Window Name");
}
void glInit()
{
glutReshapeFunc(reshape);
glutIdleFunc(idle);
glutKeyboardFunc(keyboard);
glutMouseFunc(mouse);
glutDisplayFunc(display);
glBlendFunc(GL_SRC_ALPHA, GL_ONE); //CRASH!
}
int main(int argc, char **argv)
{
glutInit(&argc, argv);
glInit(); // CRASH HERE
camInit(); //ok
allocVars(); // CRASH HERE
trackingInit();
glutMainLoop();
return 0;
}
Acccording to other posts, in order to make gl calls I have to have a valid openGL context first. (For strange reasons in Windows it works even if the context is not valid yet.)
That is why I move everything after glutInit and glInit functions but this application always crashes in gl functions like
glGenTextures() inside of allocVars(); in GLWindow(); or in
glBlendFunc() inside of glInit()
I wonder what am I missing here and/or how can I check I have a valid opengl context?
Thanks in advance
answer is in the comments ↑