NAME

SG_Light — Agar-SG light source node

SYNOPSIS

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

DESCRIPTION

The SG_Light node defines a light source in a SG(3) scene-graph. Each light source is associated with a priority number, which determines which lights are used in the rendering. The number of lights supported for rendering is dependent on the renderer implementation.

INHERITANCE HIERARCHY

AG_Object(3) -> SG_Node(3) -> SG_Light.

INITIALIZATION

SG_Light *
SG_LightNew(SG_Node *parent, const char *name);

void
SG_LightAmbient(SG_Light *lt, M_Color c);

void
SG_LightDiffuse(SG_Light *lt, M_Color c);

void
SG_LightSpecular(SG_Light *lt, M_Color c);

void
SG_LightSpot(SG_Light *lt, M_Real cutoff, M_Real exponent, M_Vector3 dir);

The SG_LightNew() function allocates, initializes, and attaches a SG_Light object.

The functions SG_LightAmbient(), SG_LightDiffuse() and SG_LightSpecular() configure the colors associated with the ambient, diffuse and specular components of the light source.

SG_LightSpot() sets the spot parameters of the light source. cutoff specifies the cutoff angle in degrees, exponent specifies the light intensity (the higher the exponent, the more focused the light source; a value of 0 provides uniform distribution), and dir is the direction vector. If the cutoff angle is < 180 degrees, the light source is directional, otherwise it is treated as a point source and the direction vector is ignored.

INTERNAL WIDGET API

void
SG_LightSetup(SG_Light *lt, SG_View *sv);

The SG_LightSetup() function sets up the renderer states associated with a light, prior to rendering. This function is usually invoked from the draw() operation of an SG_View(3) (or derived) widget, prior to rendering a scene.

STRUCTURE DATA

For the SG_Light object:

int pri

Priority of light source when number of sources is limited (0 = highest priority).

M_Color ambient

Ambient color component of source.

M_Color diffuse

Diffuse color component of source.

M_Color specular

Specular color component of source.

M_Real spot_cutoff

Spotlight cutoff angle (or 180 for point source).

M_Real spot_exponent

Spotlight intensity distribution.

M_Vector3 spot_dir

Spotlight direction.

M_Real Kc

Constant light attenuation factor.

M_Real Kl

Linear light attenuation factor.

M_Real Kq

Quadratic light attenuation factor.

SEE ALSO

M_Real(3), M_Vector(3), SG(3), SG_Intro(3), SG_Node(3), SG_View(3)

HISTORY

The SG_Light node class first appeared in Agar 1.6.0.