Should I translate first or rotate first?

Question

I'm trying to create a simple scene where I can walk around, with the criteria of being able to pan around and walk around with the keys. However, in my draw scene function, when I translate my scene than rotate, the panning around doesn't work properly as the entire scene just rotates around me, causing objects to go through me. When I rotate than translate my scene, I can pan around properly, however, I can move only in a certain direction, so if I pan around to my right 90 degrees, I'll move left instead of going forward. Is there anyway where I can put these 2 effects together?

This is the code that I use to draw my view:

glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
glLoadIdentity();
glPushMatrix();

glTranslated(xposition, 0, zposition); //This is where I translate my views
glRotated(yrot, 0, 1, 0); //

glEnableClientState(GL_NORMAL_ARRAY);
glEnableClientState(GL_COLOR_ARRAY);
glEnableClientState(GL_VERTEX_ARRAY);
glBindBuffer(GL_ARRAY_BUFFER_ARB, quadVBO);

glNormalPointer(GL_FLOAT, 0, (void*)sizeof(sideArray));
glColorPointer(3, GL_FLOAT, 0, (void*)sizeof(sideArray)+sizeof(normals));
glVertexPointer(3, GL_FLOAT, 0, 0);

glDrawArrays(GL_QUADS, 0, sizeof(sideArray)/sizeof(GLfloat)/3);

glPopMatrix();
glFlush();
glDisableClientState(GL_VERTEX_ARRAY);  
glDisableClientState(GL_COLOR_ARRAY);
glDisableClientState(GL_NORMAL_ARRAY);
glBindBufferARB(GL_ARRAY_BUFFER_ARB, 0);

Here are some pictures that illustrate my problem right now:

Rotate then translate:

Pic1

http://dl.dropbox.com/u/2747708/Screen%20Shot%202012-04-03%20at%2010.17.39%20PM.PNG

Pic2

I can imitate the turn of the camera

http://dl.dropbox.com/u/2747708/Screen%20Shot%202012-04-03%20at%2010.17.48%20PM.PNG

Pic3

However, when I walk forward, it only walks in one direction, and not the direction I'm looking at.

http://dl.dropbox.com/u/2747708/Screen%20Shot%202012-04-03%20at%2010.18.30%20PM.PNG

http://dl.dropbox.com/u/2747708/Screen%20Shot%202012-04-03%20at%2010.18.39%20PM.PNG

Translate then Rotate:

Pic1

http://dl.dropbox.com/u/2747708/Screen%20Shot%202012-04-03%20at%2010.19.44%20PM.PNG

Pic2

I can move around freely, walking straight to any direction I'm looking at.

http://dl.dropbox.com/u/2747708/Screen%20Shot%202012-04-03%20at%2010.19.52%20PM.PNG

Pic3

However, when I rotate the scene, the entire thing rotates, which causes objects to clip through me and doesn't "pan" through the view anymore like when I rotate then translate my view.

http://dl.dropbox.com/u/2747708/Screen%20Shot%202012-04-03%20at%2010.20.01%20PM.PNG

Answer 1

Your problem isn't with the order of transformations. You should be rotating then translating.

The problem is that you aren't taking rotation into account when moving. The formula for movement:

movementX = sin(direction);
movementY = cos(direction);

where direction is the number of radians turned clockwise from north, and positive X is east, and positive Y is north.