Rotating a 3D sphere according to geolocation

beginners
#1

Hi all,

I’ve been searching the forum for an answer, but I really didn’t manage to pull it of.
My challenge is as follows: I have a 3D sphere with an earth map and I would like to be able to rotate the sphere just so that a given geolocation (longitude & latitude) will be centered.

If I try to rotate the sphere with -60.0f latitude and 0.0f longitude it works (http://sht.tl/aMw), this also applies when I try 0.0f latitude and -30.0f longitude (http://sht.tl/KVcP). But when I try to combine them and try -60.0f latitude and -30.0f it doesn’t work anymore (http://sht.tl/qbLst).

I was already expecting this to happen, but I really can’t think of a way to calculate the correct rotations for both axes.

This is the code where I draw my sphere:

  
  
       ofPushMatrix();  
            ofTranslate(current_position.x, current_position.y);  
              
            ofPushMatrix();  
                ofRotateY( -lat );  
                ofRotateX( -90 - lon );  
                  
                glPushMatrix();  
                glEnable(GL_DEPTH_TEST);  
                shader.begin();  
                shader.setUniformTexture("colormap", earth, 1);   
                shader.setUniformTexture("bumpmap", bumpmap, 2);  
                shader.setUniform1i("maxHeight", 5);  
                  
                gluSphere(quadric, current_radius, 400, 400);  
                shader.end();  
                glDisable(GL_DEPTH_TEST);  
                glPopMatrix();  
          
            ofPopMatrix();  
          
            ofSetColor(255,0,0,140);  
            ofCircle(0,0,5);  
          
        ofPopMatrix();

Is this a very complicated math problem?

#2

I figured it out, wasn’t that hard after all.

  
ofPushMatrix();  
            glTranslatef(current_position.x, current_position.y, 0);  
                       
                ofRotateY( -current_lat );  
                ofRotateX( -current_lon );  
                  
                ofPushMatrix();  
                glEnable(GL_DEPTH_TEST);  
                shader.begin();  
                shader.setUniformTexture("colormap", earth, 1);  
                shader.setUniformTexture("bumpmap", bumpmap, 2);  
                shader.setUniform1i("maxHeight", 5);  
                  
                ofRotateX(-90);  
          
                gluSphere(quadric, current_radius, 360, 360);  
                shader.end();  
                glDisable(GL_DEPTH_TEST);  
                ofPopMatrix();  
          
          
        ofPopMatrix();