I want to change background color of the window after pressing the button, but my program doesn't work, can somebody tell me why, thanks in advance
int main(int argc, char* argv[])
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
glutInitWindowSize(800, 600);
glutInitWindowPosition(300,50);
glutCreateWindow("GLRect");
glClearColor(1.0f, 0.0f, 0.0f, 1.0f); <---
glutDisplayFunc(RenderScene);
glutReshapeFunc(ChangeSize);
glutMainLoop();
system("pause");
glClearColor(0.0f, 1.0f, 0.0f, 1.0f); <---
return 0;
}
Answer
glClearColor does not do any clearing itself -- it just sets what the color will be when you do actually clear. To do the clearing itself, you need to call glClear with (at least) COLOR_BUFFER_BIT.
Edit: it's been quite a while since I used glut, so the details of this could be wrong, but if memory serves, to change the screen color in response to pressing a key on the keyboard, you'd do something like this:
void keyboard (unsigned char key, int x, int y)
{
// we'll switch between red and blue when the user presses a key:
GLfloat colors[][3] = { { 0.0f, 0.0f, 1.0f}, {1.0f, 0.0f, 0.0f } };
static int back;
switch (key) {
case 27:
exit(0);
default:
back ^= 1;
glClearColor(colors[back][0], colors[back][1], colors[back][2], 1.0f);
glutPostRedisplay();
}
}
void draw() {
glClear(GL_COLOR_BUFFER_BIT);
// other drawing here...
}
int main() {
// glutInit, glutInitDisplayMode, etc.
glutDisplayFunc(draw);
glutKeyboardFunc(keyboard);
glutMainLoop();
}
Basically, you do all your drawing in whatever function you pass to glutDisplayFunc. Almost anything else just changes the state, then calls PostRedisplayFunc(); to tell glut that the window needs to be redrawn. Warning: as I said, it's been a while since I used glut and I haven't tested this code. It shows the general structure of a glut program to the best of my recollection, but don't expect it to work exactly as-is.