//rotate
vec_set(camera.pan, vector((camera.pan+(key_a-key_d)*time_frame*5)%360, 0,0));

// move
vec_set(camera.x, vector(camera.x+(key_w-key_s)*cosv(camera.pan)*time_frame*5, camera.y+(key_w-key_s)*sinv(camera.pan)*time_frame*5, 0));

VECTOR vtemp;
...
vec_set ( vtemp, vector ( kwy_w - key_s, key_d - key_a, 0 );
vec_rotate ( vtemp, camera.pan );
vec_normalize ( vtemp, Speed * time_step );
vec_add ( camera.x, vtemp );

// move
		vNewPosition = vector(
			camera.x+(key_w-key_s)*cosv(camera.pan)*time_step*WALK_SPEED  +(key_a-key_d)*cosv(camera.pan+90)*time_step*WALK_SPEED,
			camera.y+(key_w-key_s)*sinv(camera.pan)*time_step*WALK_SPEED  +(key_a-key_d)*sinv(camera.pan+90)*time_step*WALK_SPEED,
			0
		);
		
		
		vec_set(camera.x, vNewPosition);