typedef GLfloat GLTPoint[3];

struct BlockedSolid
{
	GLTPoint3 lower_left_back;
	GLTPoint3 upper_right_frot;
};

struct BlockedSolidGroup
{
	vector<BlockedSolid> blocked_solids; 
	GLint lowest_starting_x;
};

struct TotalBlockedSpace
{
	vector<BlockedSolidGroup> all_blocked_space;
	GLint group_size;//range of x-values covered by each BlockedSolidGroup
	GLint max_length;//longest (x-length) allowed for a BlockedSolid
};



boolean CheckCoordinateBlocked(GLTVector3 test_point, TotalBlockedSpace blocked_space)
{
	GLint solid_group;
	GLint solid_group_size;
	GLint i;

	solid_group = test_point[0] / blocked_space.group_size;//find correct zone to search
	solid_group_size = blocked_space.all_blocked_space[solid_group].size();//determine size of zone to be searched
...snip
}