Defines a spot light object and its behavior.

A spot light is similar to a theater spot or flashlight which projects a parallel-like cone of light containing a hotspot and surrounding falloff. The hotspot is described by the angle of the inner cone of maximum intensity emitted by the light.  outer is the angle of the outer conical section of light surrounding the hotspot, known as falloff, which is co-axial from the vertex of the hotspot, wherein light intensity decreases from the maximum at the hotspot edge to 0 at the outer edge of the falloff. This is shown in figure 1.
 
 
 
 


 
Figure 1. Spot Light diagram

HT_Filter, HT_Light, HT_Distant_Light, HT_Point_Light, HT_Ambient_Light, chapter 8, "Lighting and Material Functions"

concentration, set_concentration

Queries or sets the intensity of the overall falloff factor for the light.

direction, set_direction

Queries or sets the vector indicating the center of the light points.

falloff, set_falloff

Queries or sets the falloff rate between the inner and outer cones.

inner, set_inner

Queries or sets the hotspot area of maximum illumination.

normalized_dir

Queries the normalized version of light direction as a unit vector.

outer, set_outer

Queries or sets the angle of the outer most limit that receives any light.

position, set_position

Queries or sets the point in space of the light source.

HT_Spot_Light

Purpose

Queries or sets the intensity of the overall falloff factor for the light.

float concentration () const

void set_concentration (float con, HT_Boolean shared = HK_False)

.

Purpose

Queries or sets the vector indicating the center of the light points.

HT_Vector direction () const

void set_direction (HT_Vector const & dir, HT_Boolean shared = HK_False)

.

Purpose

Queries or sets the falloff rate between the inner and outer cones¾between the outer edge of the hotspot and the outer edge of the falloff.

float falloff () const

void set_falloff (float fall, HT_Boolean shared = HK_False)

.

Purpose

Constructs an HT_Spot_Light object.

HT_Spot_Light::HT_Spot_Light (HT_Point const & pos, HT_Vector const & dir, float inner, float outer,
                              float falloff, float concentration)

Class HT_Lighting_Info returns the result of illumination information, basically color and direction for lights. illuminate determines how much light is contributed to that part of the object that is illuminated, whereas position is the coordinate point of the illuminated object.

HT_Lighting_Info HT_Spot_Light_Data::illuminate (
    stack       HT_Rendition const *    hr,
    stack       HT_Vector const *       normal,
    stack       HT_Point const *        position,
    stack       HT_Parameter const *    parameter) const

Purpose

Queries or sets the hotspot area of maximum illumination.

float inner () const

void set_inner (float in, HT_Boolean shared = HK_False)

.

Purpose

Queries the normalized version of light direction as a unit vector.

HT_Vector normalized_dir () const

.

Purpose

Queries or sets the angle of the outer most limit that receives any light.

float outer () const

void set_outer (float out, HT_Boolean shared = HK_False)

.

Purpose

Queries or sets the point in space of the light source.

HT_Point position () const

void set_position (HT_Point const & pos, HT_Boolean shared = HK_False)

.

Purpose

Returns the shadow type.

HT_Shadow_Type shadow_type () const

.

Purpose

Returns true if the use limit is activated.

HT_Boolean use_limits () const

.

Purpose

Returns the start limit.

float start_limit () const

.

Purpose

Returns the end limit.

float end_limit () const

.