lg_landscape.c File Reference

Functions
LG_QTNode	lg_qtnode (int id, const char *name, Rec2Df *bounds, void *data)
void	lg_qtnode_set_altitude (LG_QTNode *node, float altitude)
void	lg_qtnode_add_child (LG_QTNode *node, LG_QTNode *child, int quadrant, float altitude)
LG_QTNode *	lg_qtnode_get_root (LG_QTNode *node)
void	lg_add_scenenode_from_qtnode (LG_SceneNode *top_scene_node, LG_QTNode *qt_node)
void	lg_traverse_landscape (LG_QTNode *node, int(*func)(LG_QTNode *))
void	lg_traverse_printout_landscape (LG_QTNode *node, zboolean extra_info)
void	lg_qtnode_info (LG_QTNode *node)
int	lg_qtnode_info2 (LG_QTNode *node)

Detailed Description

=== QuadTree implementation ===

LG_QTNode = LG QuadTree Node

QuadTree quadrants: LG_NW (0), LG_NE (1), LG_SW (2), LG_SE (3)

struct LG_QTNode {
   int             id;                                     // User-defined
   char            name[QUADTREE_NAME_MAX_LEN + 1];
   LG_QTNode       *parent;
   LG_QTNode       *child[4];                              // N-W, N-E, S-W, S-E
   int             quadrant;                               // LG_NW, LG_NE, LG_SW, LG_SE
   Rec2Df          bounds;                                 // Actually a bounding square, ie w = h
   vec3_t          center;
   float           altitude;
   zboolean        is_leaf;
   void            *data;                                  // Usually a mesh
};

Function Documentation

lg_qtnode()

LG_QTNode lg_qtnode	(	int	id,
		const char *	name,
		Rec2Df *	bounds,
		void *	data
	)

Create a new landscape node (LG_QTNode)

If no bounding rectangle is provided (bounds == NULL), default one is {-1.0, -1.0, 2.0, 2.0}

No need to free anything when done (no dynamically allocated memory)

Parameters

id	Node's id
name	Node's name
bounds	A pointer to a bounding rectangle (actually must be a square), may be NULL
data	A pointer to data (terrain tile, mesh, whatever ...), may be NULL

Returns

A LG_QTNode

lg_qtnode_set_altitude()

void lg_qtnode_set_altitude	(	LG_QTNode *	node,
		float	altitude
	)

Set specifically landscape node's altitude

Parameters

altitude

lg_qtnode_add_child()

void lg_qtnode_add_child	(	LG_QTNode *	node,
		LG_QTNode *	child,
		int	quadrant,
		float	altitude
	)

Add child node to landscape node

WARNING: node == child, or adding twice the same node, will lead to undefined behaviour (because adding a node changes that node's bounds)

-> NEVER REUSE NODES, CREATE NEW ONES INSTEAD (they're cheap)

Parameters

node	A pointer to a LG_QTNode
child	A pointer to a LG_QTNode
quadrant	One of LG_NW, LG_NE, LG_SW, LG_SE (lg_quadrant)
altitude	Relative altitude

lg_qtnode_get_root()

LG_QTNode* lg_qtnode_get_root

(

LG_QTNode *

node

)

Get the root node

Parameters

node	A pointer to a LG_QTNode

Returns

The root LG_QTNode if OK, NULL on error

lg_add_scenenode_from_qtnode()

void lg_add_scenenode_from_qtnode	(	LG_SceneNode *	top_scene_node,
		LG_QTNode *	qt_node
	)

Parse a quad tree and create/add a scene node for each leaf (to the top scene node)

• Scene node's id = qt_node->id + QUADTREE_TO_SCENENODE_ID_SHIFT
• Scene node's name = "%s_<%d%d>" <- qt_node->name, qt_node->id, i++

Parameters

top_scene_node	A pointer to a LG_SceneNode
qt_node	A pointer to a LG_QTNode

lg_traverse_landscape()

void lg_traverse_landscape	(	LG_QTNode *	node,
		int(*)(LG_QTNode *)	func
	)

Go from top to bottom, starting at node (may be different from the top node)

Call (*func)(node) for each leaf

Parameters

node	A pointer to a LG_QTNode
func	A func pointer

lg_traverse_printout_landscape()

void lg_traverse_printout_landscape	(	LG_QTNode *	node,
		zboolean	extra_info
	)

Go from top to bottom

Print out quad tree structure (quite nicely) -> node->name (node->id/quadrant/altitude)

Parameters

node	A pointer to a LG_QTNode
extra_info	If TRUE, print out extra info

lg_qtnode_info()

void lg_qtnode_info

(

LG_QTNode *

node

)

Print out LG_QTNode info

Parameters

node	A pointer to a LG_QTNode

lg_qtnode_info2()

int lg_qtnode_info2

(

LG_QTNode *

node

)

Print out LG_QTNode info

Same as above func but returns (int)0, so suitable to use with lg_traverse_landscape()

Parameters

node	A pointer to a LG_QTNode