Hello,
I wrote script for rotating camera around certain point with certain radius while camera is still looking at that point, which can be an entity:
Code:
long radius;
	long posx=-800;
	long posy=0;
        var up=1;
	var speed=20*time_step;

vec_to_angle(camera.pan,vec_diff(NULL,some_entity.x,camera.x));
if(key_cul)
		{
			
			if(up==1)
		{
			if(posx<=radius)
			{
				posx+=speed;
				posy=sqrt((radius*radius)-(posx*posx));
			}
			
			if(posx>=radius)
			{
				up=0;
			}
			
		}
		if(up==0)
		{
			if(posx>=-radius)
			{
				posx-=speed;
				posy=-sqrt((radius*radius)-(posx*posx));
			}
			
			if(posx<=-radius)
			{
				up=1;
			}	
		}


It works, however the rotation speed is not linear (because sqrt function is not linear). The questin is, how could I achieve linear rotation speed? Or is there any function (lite-c) to achieve such rotation of camera?
It should work similary as 3D RPG camera with free rotation mode
(eg Sacred 2, Dungeon Siege...etc)