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SG_NODE(3)		    Library Functions Manual		    SG_NODE(3)

NAME
       SG_Node -- Agar-SG base node class

SYNOPSIS
       #include	<agar/core.h>
       #include	<agar/sg.h>

DESCRIPTION
       SG_Node	is  the	base class for any element of a	SG(3) scene.  This in-
       cludes geometrical elements (e.g., SG_Object(3))	as well	as non-geomet-
       rical elements (e.g., SG_Light(3), SG_Camera(3)).

       Nodes are organized in a	tree structure,	and the	position of a  SG_Node
       in  relation to its parent is determined	by a 4x4 transformation	matrix
       (see M_Matrix(3)).

INHERITANCE HIERARCHY
       AG_Object(3) -> SG_Node.

INTERFACE
       void SG_RegisterClass(SG_NodeOps	*ops)

       void SG_NodeInit(void *node, const char *name, const  SG_NodeOps	 *ops,
       Uint flags)

       void * SG_NodeAdd(void *pnode, const char *name,	const SG_NodeOps *ops,
       Uint flags)

       void SG_NodeAttach(void *pnode, void *node)

       void SG_NodeDetach(void *pnode, void *node)

       void SG_NodeDraw(SG *sg,	SG_Node	*node, SG_View *view)

       The  SG_RegisterClass()	function registers a new node class, described
       by the given SG_NodeOps structure.

       The SG_NodeInit() function initializes the given	SG_Node	structure.  It
       is usually invoked from node constructor	functions.  The	name  argument
       is  a  string  identifier  for  the node.  ops points to	the SG_NodeOps
       structure which contains	class information.  The	flags argument	should
       be  0.	The  SG_NodeAdd()  variant also	allocates, initializes and at-
       taches the node to a parent node.

       The SG_NodeAttach() and SG_NodeDetach() functions attach/detach a  node
       to/from a given parent.

       The SG_NodeDraw() function is used to render a node to the display.  It
       is  normally only invoked from the draw operation of SG_View(3) (or an-
       other visualization widget derived from	SG_View).   SG_NodeDraw()  as-
       sumes that the node's transformation matrix has already been applied to
       the current viewing matrix.

NODE TRANSFORMATIONS
       The  following  calls  multiply a node's	transformation matrix T	with a
       translation, scaling or rotation	matrix.	 Note that the	T  matrix  may
       also be manipulated directly with the M_Matrix(3) interface.

       void SG_Identity(SG_Node	*node)

       void SG_Translate(SG_Node *node,	M_Real x, M_Real y, M_Real z)

       void SG_Translatev(SG_Node *node, M_Vector3 v)

       void SG_TranslateX(SG_Node *node, M_Real	x)

       void SG_TranslateY(SG_Node *node, M_Real	y)

       void SG_TranslateZ(SG_Node *node, M_Real	z)

       void SG_Scale(SG_Node *node, M_Real s)

       void SG_Rotatev(SG_Node *node, M_Real theta, M_Vector3 axis)

       void SG_RotateI(SG_Node *node, M_Real theta)

       void SG_RotateJ(SG_Node *node, M_Real theta)

       void SG_RotateK(SG_Node *node, M_Real theta)

       void SG_Rotatevd(SG_Node	*node, M_Real degrees, M_Vector3 axis)

       void SG_RotateId(SG_Node	*node, M_Real degrees)

       void SG_RotateJd(SG_Node	*node, M_Real degrees)

       void SG_RotateKd(SG_Node	*node, M_Real degrees)

       void SG_GetNodeTransform(void *node, M_Matrix44 *T)

       void SG_GetNodeTransformInverse(void *node, M_Matrix44 *T)

       M_Vector3 SG_NodePos(SG_Node *node)

       M_Vector3 SG_NodeDir(SG_Node *node)

       M_Real SG_NodeSize(SG_Node *node)

       SG_Identity()  sets  the	transformation matrix of the node to the iden-
       tity matrix.

       The SG_Translate*() functions multiply T	by a translation matrix.

       The SG_Scale() function multiplies T by a uniform scaling matrix.

       SG_Rotate*() multiply T by a rotation matrix.  Angles are given in  ra-
       dians, except for SG_Rotate*d() variants	which accept angular arguments
       in degrees.

       SG_Rotatev() generates a	rotation of theta radians around axis.

       Note  that  most	of the preceding functions are trivial wrappers	around
       M_Matrix(3) functions (applied to the transformation matrix  T  of  the
       node).

       The SG_GetNodeTransform() function returns a transformation matrix map-
       ping the	node back to world coordinates (i.e., by computing the product
       of   the	  transformation  matrices  of	the  node  and	its  parents).
       SG_GetNodeTransformInverse() returns the	inverse	of this	matrix.

       The SG_NodePos()	function returns a vector  representing	 the  absolute
       world  coordinates of a node.  SG_NodeDir() returns a normalized	vector
       representing the	direction of a node with respect to the	world  Z  axis
       (i.e.,  the  Z axis of the origin node).	 SG_NodeSize() returns the ab-
       solute scaling factor of	an object.

STRUCTURE DATA
       For the SG_Node object:

       Uint flags     Option flags (see	"FLAGS"	section).
       SG *sg	      Back pointer to parent SG(3) object.
       M_Matrix44 T   Transformation matrix (relative to parent	node).

FLAGS
       For the SG_Node object:

       SG_NODE_SELECTED	  Node is selected (e.g., for edition).

EXAMPLES
       See sg/sg_dummy.c in the	Agar source distribution for an	 example  node
       class implementation.

SEE ALSO
       M_Matrix(3), M_Real(3), M_Vector(3), SG(3), SG_Intro(3)

HISTORY
       The SG_Node node	class first appeared in	Agar 1.6.0.

Agar 1.7		       December	21, 2022		    SG_NODE(3)

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