Examples - General Ray Data

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These examples cover the FRED general Ray Data scripting commands:

"Add" - add a ray buffer,

"Get" - retrieves information from a ray buffer,

"Set" - changes the active ray buffer.

The structure listed below contains the parameters required to define ray data:

T_RAY

"Add" a ray

The following example constructs polar grid of rays in the z=0 plane. Here the rays are positioned like the spokes of a wheel:

Dim r As T_RAY

nspokes=9 'number of spokes

nrings=5 'number of rings

aprad=2 'aperture radius
ang=2*Pi/nspokes
spc=aprad/nrings
Pi=Acos(-1) 'define Pi

'set z-position, power and make rays active (traceable)

r.z=0 'set rays to be in the z=0 plane
r.power=1
r.active=True

'center ray
r.x=0:r.y=0
id=AddRay(r)

'spokes

For i=spc To aprad Step spc
For j=0 To 2*Pi-(ang) Step ang
   r.x=i*Cos(j): r.y=i*Sin(j)
   id = AddRay ( r )
Next j
Next i
RaySummary             'print ray summary to verify creation

"Get" ray data

The "Get" commands are used to return either ray count or specific ray information.

Getting ray count involves a single command that returns the number of rays in the active ray buffer:

count=GetRayCount()

GetRay populates an existing T_RAY structure with the current ray parameters. The example below gets the data for ray 12 and places it in T_RAY structure r. Here, some of the data is printed to the output window.

Dim r As T_RAY

If IsRayLive(i) Then

GetRay 12, r

Print r.x,r.y,r.z

Print "The ray is active -", r.active

End If

"Set" a ray

Use "SetRay" to change the parameters of an existing ray. Here, ray number 35 is made inactive (nontraceable):

Dim r As T_RAY

r.active=False

SetRay 35, r

Looping over Rays

The recommended method of looping over rays is shown below. The commands GetFirstRay and GetNextRay retrieve individual ray data into the T_RAY structure. See Multi-Threaded Raytracing for further details on looping over rays.

success = GetFirstRay(i,tr)

While success

: :

success = GetNextRay(i,tr)

Wend