Defining Surfaces - Introduction

Rayshade defines the characteristics of a surface through a number of keywords (see below), there are also a number of ways in which surface characteristics can be applied to an object. The simplest way is to define a named surface and then use that name when defining the primitive; alternatively, the surface definition may be placed with the primitive, after the primitive's keyword and before its parameters; the last way is to apply a surface definition to an instance of an object.

        surface surface-name surface-definition

The surface keyword is used to associate a name with a surface definition (see "PeachPuff" in the example below). Any object that does not have a surface definition associated with it is assigned Rayshade's default surface (a white/grey).

The example below, demonstrates each of the ways to apply surfaces to objects.

In the first object (box) a defined surface (PeachPuff) is used; this is (in my opinion) the simplest and most straight-forward way to apply a surface to an object.
The second object (torus) has its surface definition with the object definition.
The next object (cone) has no surface - it uses Rayshade's default surface (grey).
The last object is a blue bowl: the bowl is created without any surface definitions, then when the bowl is included in the scene a surface (blue) is applied to it; this technique allows different surfaces to be applied to the same object!

Figure 4-1

        /*
           surf1.ray
           ways to define surfaces
           sp  8 mar 92
        */
        eyep 6 12 7
        lookp 2.5 2.5 3
        light 1 point 8 5 5
        background .9 .9 .9
        screen 300 200

        /* defining a "peach" surface */
        surface PeachPuff
            diffuse  1. .75 .65
            specular .25 .25  .25    reflect .75

        /* primitive using a defined surface */
        box PeachPuff  0 0 0  5 5 1.5

        /* primitive with surface definition */
        torus
            ambient .2 .1 .03    diffuse 1. .5 .15
            1.5 .5   2.5 2.5 2.5   0 0 1

        /* primitive using the default surface */
        cone .5  2.5 2.5 1.5  0  2.5 2.5 5

        /* define a "blue" surface */
        surface blue
            diffuse .4 .4 1  transp .75

        /* create a "bowl" object (default surface) */
        name bowl difference
            difference
                sphere 1.5  2.5 2.5 5.5
                box 0 0 5  5 5 7.1
            end
            sphere 1.4  2.5 2.5 5.5
        end
        object blue bowl

Go to next section: Ambient.

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THE END - Notes on Rayshade - 4 - Defining Surfaces