I am using OpenGL with GLUT. I have a gluPerspective viewport with which I wish to output 2D text ''over the top of it'', so that if I print text at 10,10 it will print it at pixel coord 10,10, not world coordinate 10,10.
I can successfully do so in an orthographic viewport, but not in a 3D viewport. Can anybody help or point me in the right direction!?
Thanks!
OpenGL 2D Text in 3D Space
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Hi, this is my first post so please be gentle
I am using OpenGL with GLUT. I have a gluPerspective viewport with which I wish to output 2D text ''over the top of it'', so that if I print text at 10,10 it will print it at pixel coord 10,10, not world coordinate 10,10.
I can successfully do so in an orthographic viewport, but not in a 3D viewport. Can anybody help or point me in the right direction!?
Thanks!
I am using OpenGL with GLUT. I have a gluPerspective viewport with which I wish to output 2D text ''over the top of it'', so that if I print text at 10,10 it will print it at pixel coord 10,10, not world coordinate 10,10.
I can successfully do so in an orthographic viewport, but not in a 3D viewport. Can anybody help or point me in the right direction!?
Thanks!
Since this is your first post: try to post OpenGL specific questions in the OpenGL forum.
To your question: You could do it in a 3D viewport, but it''s not that trivial. The simplest way is to use orthographic projection, esp. if you already have it working there.
Here is some code snippet:
// assume, you are currently in perspective 3D projection.
// And that the current matrix mode is GL_MODELVIEW
// Draw your 3D scene here
// Save your projection matrix
glMatrixMode(GL_PROJECTION);
glPushMatrix();
// Switch to orthographic projection
glLoadIdentity();
glOrtho(...)
// Back to the modelview matrix mode, so that you can translate/scale your text
glMatrixMode(GL_MODELVIEW);
// Render your 2D text
// get back the old prespective projection matrix
glMatrixMode(GL_PROJECTION);
glPopMatrix();
glMatrixMode(GL_MODELVIEW);
// And you are in perspective mode again.
/ Yann
To your question: You could do it in a 3D viewport, but it''s not that trivial. The simplest way is to use orthographic projection, esp. if you already have it working there.
Here is some code snippet:
// assume, you are currently in perspective 3D projection.
// And that the current matrix mode is GL_MODELVIEW
// Draw your 3D scene here
// Save your projection matrix
glMatrixMode(GL_PROJECTION);
glPushMatrix();
// Switch to orthographic projection
glLoadIdentity();
glOrtho(...)
// Back to the modelview matrix mode, so that you can translate/scale your text
glMatrixMode(GL_MODELVIEW);
// Render your 2D text
// get back the old prespective projection matrix
glMatrixMode(GL_PROJECTION);
glPopMatrix();
glMatrixMode(GL_MODELVIEW);
// And you are in perspective mode again.
/ Yann
Modify as necessary to suit your needs:
void print(int x, int y, const char *string){ //Assume we are in MODEL_VIEW already glPushMatrix (); glLoadIdentity (); glMatrixMode(GL_PROJECTION); glPushMatrix (); glLoadIdentity(); GLint viewport [4]; glGetIntegerv (GL_VIEWPORT, viewport); gluOrtho2D (0,viewport[2], viewport[3], 0); glDepthFunc (GL_ALWAYS); glColor3f (1,1,1); glRasterPos2f(x, y); for (int i = 0; string!= '\0'; ++i) glutBitmapCharacter(GLUT_BITMAP_HELVETICA_18, string);<br> glDepthFunc (GL_LESS);<br> glPopMatrix ();<br> glMatrixMode(GL_MODELVIEW);<br> glPopMatrix ();<br>}<br> </pre> </i> <br><br><SPAN CLASS=editedby>[edited by - invective on May 25, 2002 1:03:53 PM]</SPAN>
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