Representation of a 3D light source.
typedef struct { API_3D_Head head; API_LghtSouID type; Int32 status; Int32 filler_1[2]; API_RGBColor lightRGB; double posx; double posy; double posz; double dirx; double diry; double dirz; double radius; double cosa; double cosb; double afall; double dist1; double dist2; double dfall; } API_LghtType;
Members
- head
- Header information of this component. This specifies the type (
API_LghtID
) and database index. - type
- The type of the light
- status
- The light casts shadow or not.
- lightRGB
- The color of the light source.
- posx, posy, posz
- The local origin of the light.
- dirx, diry, dirz
- The direction of the light.
- radius
- The radius of the light source.
- cosa
- The cosine of the angle of the cone within the light has its maximum intensity.
- cosb
- The cosine of the angle of the cone within the intensity falls to zero.
- afall
- The falloff control of the light (decrease of intensity depending on the cone angle).
- dist1, dist2
- The clipping values along the x axis.
- dfall
- Controls the fall-of of intensity depending on the distance.
Remarks
A light source radiates lightRGB
colored light from the local origin (posx
, posy
, posz
) along the direction vector (dirx
, diry
, dirz
). The light is projected parallel to the direction vector from a point or circle source. (See figure below!) It has its maximum intensity within the alpha-angle frustum of a cone and falls to zero at the beta-angle frustum of a cone. This falloff is controlled by the afall
parameter. (Zero gives the light a sharp edge, higher values mean that the transition is smoother.) The effect of the light is limited along the axis by the dist1
and dist2
clipping values. The dfall
parameter controls the decrease in intensity depending on the distance. (Zero value means a constant intensity, bigger values are used for stronger falloff.)
The type
of the light source can be one of the API_LghtSouID member.
The status
must be APILight_CastShadow
if you want Archicad to calculate shadow casting from this light source, or else remain it zero.

Requirements
- Version: API 1.3 or later
- Header: APIdefs_3D.h
See Also
API_3D_Head, API_LghtSouID, API_RGBColor, API_Component3D,
3D Manager, API Types