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Why is glOrtho not changing anything?
Why can templates only be implemented in the header file?Why doesn't glCopyTexSubImage2D copy my square correctly?OpenGL Picking with PygletWhy is “using namespace std;” considered bad practice?Why are elementwise additions much faster in separate loops than in a combined loop?Why does changing 0.1f to 0 slow down performance by 10x?Why is reading lines from stdin much slower in C++ than Python?Why is processing a sorted array faster than processing an unsorted array?My display() function only displays when it enters it the first time. Then it shows a blank windowWhy should I use a pointer rather than the object itself?
.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty margin-bottom:0;
This function does not change anything even though I already called glOrtho(). What's wrong with the code? Did I miss something?
void glKeyCallback(unsigned char key, int x, int y)
if (key == 'z')
width -= 10; height -= 10;
cout << "Z" << endl;
cout << width << " " << height << endl;
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0, 800, 600, 0, 0, 1);
glMatrixMode(GL_MODELVIEW);
else if (key == 'x')
width += 10; height += 10;
cout << "X" << endl;
cout << width << " " << height << endl;
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0, 100, 100, 0, 0, 1);
glMatrixMode(GL_MODELVIEW);
I expected for the scene to zoom in / out when I pressed z or x. But it does not change anything. For the record, I have already registered this on glutKeyboardFunc
c++ opengl freeglut opengl-compat
edited Mar 28 at 13:39
Nicol Bolas
305k37 gold badges511 silver badges690 bronze badges
asked Mar 27 at 11:38
Aidil RiskiAidil Riski
82 bronze badges
add a comment |
This function does not change anything even though I already called glOrtho(). What's wrong with the code? Did I miss something?
void glKeyCallback(unsigned char key, int x, int y)
if (key == 'z')
width -= 10; height -= 10;
cout << "Z" << endl;
cout << width << " " << height << endl;
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0, 800, 600, 0, 0, 1);
glMatrixMode(GL_MODELVIEW);
else if (key == 'x')
width += 10; height += 10;
cout << "X" << endl;
cout << width << " " << height << endl;
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0, 100, 100, 0, 0, 1);
glMatrixMode(GL_MODELVIEW);
I expected for the scene to zoom in / out when I pressed z or x. But it does not change anything. For the record, I have already registered this on glutKeyboardFunc
c++ opengl freeglut opengl-compat
edited Mar 28 at 13:39
Nicol Bolas
305k37 gold badges511 silver badges690 bronze badges
asked Mar 27 at 11:38
Aidil RiskiAidil Riski
82 bronze badges
Calling GL functions in callbacks is iffy, because the callback may be running in the wrong thread. Better call them only where you do your actual rendering.
– Stefan Dragnev
Mar 27 at 12:16
1
Edit in a minimal reproducible example. For all we know you aren't redrawing on a regular basis; yourglutKeyboardFunc()certainly isn't callingglutPostRedisplay().
– genpfault
Mar 27 at 13:38
add a comment |
This function does not change anything even though I already called glOrtho(). What's wrong with the code? Did I miss something?
void glKeyCallback(unsigned char key, int x, int y)
if (key == 'z')
width -= 10; height -= 10;
cout << "Z" << endl;
cout << width << " " << height << endl;
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0, 800, 600, 0, 0, 1);
glMatrixMode(GL_MODELVIEW);
else if (key == 'x')
width += 10; height += 10;
cout << "X" << endl;
cout << width << " " << height << endl;
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0, 100, 100, 0, 0, 1);
glMatrixMode(GL_MODELVIEW);
I expected for the scene to zoom in / out when I pressed z or x. But it does not change anything. For the record, I have already registered this on glutKeyboardFunc
c++ opengl freeglut opengl-compat
edited Mar 28 at 13:39
Nicol Bolas
305k37 gold badges511 silver badges690 bronze badges
asked Mar 27 at 11:38
Aidil RiskiAidil Riski
82 bronze badges
This function does not change anything even though I already called glOrtho(). What's wrong with the code? Did I miss something?
void glKeyCallback(unsigned char key, int x, int y)
if (key == 'z')
width -= 10; height -= 10;
cout << "Z" << endl;
cout << width << " " << height << endl;
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0, 800, 600, 0, 0, 1);
glMatrixMode(GL_MODELVIEW);
else if (key == 'x')
width += 10; height += 10;
cout << "X" << endl;
cout << width << " " << height << endl;
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0, 100, 100, 0, 0, 1);
glMatrixMode(GL_MODELVIEW);
I expected for the scene to zoom in / out when I pressed z or x. But it does not change anything. For the record, I have already registered this on glutKeyboardFunc
c++ opengl freeglut opengl-compat
c++ opengl freeglut opengl-compat
edited Mar 28 at 13:39
Nicol Bolas
305k37 gold badges511 silver badges690 bronze badges
asked Mar 27 at 11:38
Aidil RiskiAidil Riski
82 bronze badges
edited Mar 28 at 13:39
Nicol Bolas
305k37 gold badges511 silver badges690 bronze badges
asked Mar 27 at 11:38
Aidil RiskiAidil Riski
82 bronze badges
edited Mar 28 at 13:39
Nicol Bolas
305k37 gold badges511 silver badges690 bronze badges
edited Mar 28 at 13:39
Nicol Bolas
305k37 gold badges511 silver badges690 bronze badges
edited Mar 28 at 13:39
Nicol Bolas
305k37 gold badges511 silver badges690 bronze badges
305k37 gold badges511 silver badges690 bronze badges
asked Mar 27 at 11:38
Aidil RiskiAidil Riski
82 bronze badges
asked Mar 27 at 11:38
Aidil RiskiAidil Riski
82 bronze badges
asked Mar 27 at 11:38
Aidil RiskiAidil Riski
82 bronze badges
82 bronze badges
Calling GL functions in callbacks is iffy, because the callback may be running in the wrong thread. Better call them only where you do your actual rendering.
– Stefan Dragnev
Mar 27 at 12:16
1
Edit in a minimal reproducible example. For all we know you aren't redrawing on a regular basis; yourglutKeyboardFunc()certainly isn't callingglutPostRedisplay().
– genpfault
Mar 27 at 13:38
add a comment |
Calling GL functions in callbacks is iffy, because the callback may be running in the wrong thread. Better call them only where you do your actual rendering.
– Stefan Dragnev
Mar 27 at 12:16
1
Edit in a minimal reproducible example. For all we know you aren't redrawing on a regular basis; yourglutKeyboardFunc()certainly isn't callingglutPostRedisplay().
– genpfault
Mar 27 at 13:38
Calling GL functions in callbacks is iffy, because the callback may be running in the wrong thread. Better call them only where you do your actual rendering.
– Stefan Dragnev
Mar 27 at 12:16
Calling GL functions in callbacks is iffy, because the callback may be running in the wrong thread. Better call them only where you do your actual rendering.
– Stefan Dragnev
Mar 27 at 12:16
1
1
Edit in a minimal reproducible example. For all we know you aren't redrawing on a regular basis; your
glutKeyboardFunc() certainly isn't calling glutPostRedisplay().– genpfault
Mar 27 at 13:38
Edit in a minimal reproducible example. For all we know you aren't redrawing on a regular basis; your
glutKeyboardFunc() certainly isn't calling glutPostRedisplay().– genpfault
Mar 27 at 13:38
add a comment |
1 Answer
1
active
oldest
votes
OpenGL is not a scene graph, it's a drawing API. Just changing the projection matrix will do nothing. You also have to redraw things.
answered Mar 27 at 13:44
datenwolfdatenwolf
136k11 gold badges141 silver badges241 bronze badges
add a comment |
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OpenGL is not a scene graph, it's a drawing API. Just changing the projection matrix will do nothing. You also have to redraw things.
answered Mar 27 at 13:44
datenwolfdatenwolf
136k11 gold badges141 silver badges241 bronze badges
add a comment |
OpenGL is not a scene graph, it's a drawing API. Just changing the projection matrix will do nothing. You also have to redraw things.
answered Mar 27 at 13:44
datenwolfdatenwolf
136k11 gold badges141 silver badges241 bronze badges
add a comment |
OpenGL is not a scene graph, it's a drawing API. Just changing the projection matrix will do nothing. You also have to redraw things.
answered Mar 27 at 13:44
datenwolfdatenwolf
136k11 gold badges141 silver badges241 bronze badges
OpenGL is not a scene graph, it's a drawing API. Just changing the projection matrix will do nothing. You also have to redraw things.
answered Mar 27 at 13:44
datenwolfdatenwolf
136k11 gold badges141 silver badges241 bronze badges
answered Mar 27 at 13:44
datenwolfdatenwolf
136k11 gold badges141 silver badges241 bronze badges
answered Mar 27 at 13:44
datenwolfdatenwolf
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answered Mar 27 at 13:44
datenwolfdatenwolf
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Calling GL functions in callbacks is iffy, because the callback may be running in the wrong thread. Better call them only where you do your actual rendering.
– Stefan Dragnev
Mar 27 at 12:16
1
Edit in a minimal reproducible example. For all we know you aren't redrawing on a regular basis; your
glutKeyboardFunc()certainly isn't callingglutPostRedisplay().– genpfault
Mar 27 at 13:38