The channels are not used 'one by one' in the rendering engine; instead, they are managed as sets of channels. One such set contains space to store all the available channels. A channel set is called a 'sample'. Because all channels are included in a sample, it can store all attributes of an object in a point of space.
One sample is not enough to store the data for the entire shading process. In order to fully utilize the capabilities of the shading system of Realsoft 3D, one must know the relation between the sample objects the rendering engine uses and the shaders.
The sample objects are named according to the purpose they are used for. In some shaders, only one sample is available; some shaders provide two samples (perhaps even more in future releases or plugins for the software). For example, in the surface illumination phase, the first sample describes the properties of the surface, and the second sample describes the properties of the light. In such a situation, the channel names are prefixed by a name that specifies to which sample the channel belongs. For example, Light:illumination is the channel that contains the color of the light from a light source, and Surface:illumination is the channel that contains the total color emitted form the surface.
Below is a list of sample objects the rendering engine uses to carry out the shading process.
This sample contains the properties of a light ray (from a light source). The sample is used first in the light properties shader, next in the surface and volume filtering shaders and finally in the surface/volume illumination shaders.
The most frequently used sample. Describes the properties of a surface (boundary of a geometry). The surface sample is available in many shaders and it is used to carry the result information through the rendering system. The ray tracer computes its default shading effects to the illumination channel of the surface sample. It contains the 'result' color of the rendering process at the end of the ray tracing.
Surface filter sample
This sample is used when examining shadow casting properties of a surface in the surface filtering shader.
The particle sample is used to examine properties of particle objects that are drawn in post processing. The sample is used only in the post particle phase.
Ray hit sample
This sample is used with ray-surface hit events. The main purpose is to modify channels that affect the shape of the surface. The most important of such channels is the distance channel. This sample is used only in the ray hit shader.
The Volume sample is used to examine properties inside objects (the surface sample is used on the boundary). It is used first in the volume properties shader, then in the volume illumination and volume shading shaders.
Volume filter sample
This sample is used when examining shadow casting properties of a volume in volume filtering shaders.