Class

• <DRM Primitive Colour>

Superclass

• <DRM SEDRIS Abstract Base>

Subclass

• None.

Definition

An instance of this DRM class specifies a single colour, consisting of individual ambient, diffuse, emissive, and specular components. See 4.15.3 Colours and lighting.

Class diagram

Figure 6.224 — DRM_Primitive_Colour

Constraints

• Publishable object

Example(s)

• Consider a <DRM Geometry Model Instance> instance of a computer monitor, placed on top of a <DRM Geometry Model Instance> instance of a desk. A <DRM Positional Light> instance affecting the two objects is located so that the illumination is directed from above. Assume that these instances are present within an environment simulating an ordinary room.

  Each <DRM Polygon> instance within the desk <DRM Model> instance has a <DRM Inline Colour> component, which in turn has a <DRM Primitive Colour> component with both a <DRM Ambient Colour> component and a <DRM Diffuse Colour> component. Due to the <DRM Diffuse Colour> component, the area of the desk under the monitor that is visible to the observer appears to be in shadow. However, the shadowy area is not totally blacked out because the <DRM Ambient Colour> instance simulates the effect due to light reflected from the other parts of the environment (e.g., walls, ceiling, and other objects) that reach that area.

• Consider a <DRM Line> instance used to simulate a line of runway lights. The <DRM Colour> component of the <DRM Line> instance resolves to a <DRM Primitive Colour> instance consisting primarily (possibly completely) of a <DRM Emissive Colour> instance since the <DRM Line> instance is pretending to emit light.

• Consider a collection of <DRM Polygon> instances used to represent the surface of a sunlit lake. The <DRM Colour> components of these <DRM Polygon> instances resolve to <DRM Primitive Colour> instances, each of which consists of a <DRM Ambient Colour> component, a <DRM Diffuse Colour> component, and a <DRM Specular Colour> component.

  The <DRM Ambient Colour> component prevents any <DRM Polygon> instances in shadow from appearing black, while the <DRM Diffuse Colour> component provides most of the normal appearance of a lit object. However, since water is a reflective substance, its colour requires a <DRM Specular Colour> component to simulate light reflected from the water.