Forumchem - Forum with AI(ALICE BOT & HAL9000) and TTS

c++ - opengl coordinate system is not at -1 to 1 - stack overflow

If you arent going to be dynamically changing your projection matrix, the easiest thing to do would be to call

glScalef(.63f,.63f,1);

on your projection matrix.

You can then restrict movement based on these values.

To compute the world space coordinates at any time you should make use of gluUnProject.
assuming x and y are the width and height of your window respectively (the values you pass gluPerspective) you can find the world space coordinates like so:

double world_llx,world_lly,world_llz;
//world coordinates of lower left corner of window
gluUnProject(0, 0, 0, view_mat, proj_mat, viewport,&world_llx,&world_lly,&world_llz);
//world coordinate of upper  right corner of window
double world_urx,world_ury,world_urz;
gluUnProject(x,y,0,view_mat,proj_mat,viewport,&world_urx,&world_ury,&world_urz);

view_mat is your view matrix. proj_mat is your projection matrix. You can get both of these using glGetDouble* with GL_MODELVIEW_MATRIX and GL_PROJECTION_MATRIX.

The viewport parameter will probably have the same dimensions as your window. In any event, this is what you set with glViewport.

This assumes your XZ plane is at z == 0.