5.0

26.4. Editing Lights
You can edit a light in the palette by double clicking on it, or right clicking and choosing Edit... from the
context menu.
There are six types of light visible in both OpenGL interactive renders and photorealistic renders:
1. Ambient lights give a general background light to the scene and therefore only have intensity and
color parameters.
2. Eye lights are located at the viewpoint and also only have intensity and color parameters.
3. Point lights have a location but shine in all directions. They also have an intensity and color and
additionally can cast shadows (only available in a full photorealistic render).
4. Distant lights are directional and so have a location and target. However, the location and target
merely set up an axis down which the light shines, as these light types are infinitely far away and
their beams are parallel. As well as intensity and color parameters, they can also cast shadows in a
photorealistic render.
5. Spot lights are also directional and therefore have a location and target, as well as intensity, color
and shadow parameters. In addition, they also have parameters for affecting the light's fall off and
cone angle, as these light types are not infinitely far away, so do spread their light over a cone and
the intensity does diminish away from the light.
6. Sun simulates the sun's light. The orientation of your model is defined by north and up directions.
The position of the sun is specified as azimuth and altitude. If the sun's mode includes "Position", you
can input your location on earth, the time (using local time zone) and date and Presenter will
calculate the sun's azimuth and altitude for you. If the sun's mode includes "Intensity", Presenter will
also calculate an accurate intensity for the sun based on position, time of year and atmospheric
conditions.
There are an additional three types of light visible only in photorealistic renders:
1. Projector lights are used to project an image onto surfaces. You can define the file of the image to
be projected.
2. Sky simulates the illumination from the sky (but not the direct contribution due to the sun itself). The
orientation of your model is defined by north and up directions. The position of the sun is specified as
"sun altitude" and "sun azimuth". Whilst the direct contribution of the sun is not included, its location
will determine the appearance of the sky hemisphere. If the intensity is left at 0, Presenter will
calculate an accurate intensity for you based on the sun's position.
3. A Goniometric light is one which can emit widely varying amounts of light energy in different
directions. One goniometric source could behave exactly like a point light, another could behave
exactly like a spot light, and a third could look nothing like either of those. A goniometric light gets its
intensity distribution function (how much light goes in any one direction) from an industry-standard
file. Presenter supports CIE (*.cie), IESNA (*.ies), CIBSE (*.cib) and ILUMDAT (*.ldt) files.
Note
A complete reference manual for all light types is included with the JetStream API (see
\API\COM\documentation\shaders.chm). The JetStream API is included with JetStream Roamer
and can accessed via the JetStream installer menu.
Presenter Lighting
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