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Let's try out a computer graphics standard "The Checkered Floor". We add the following object to
the first version of the demo.pov file, the one including the sphere.
plane { <0, 1, 0>, -1
pigment {
checker color Red, color Blue
}
}
The object defined here is an infinite plane. The vector <0,1,0> is the surface normal of the plane (i.e. if
we were standing on the surface, the normal points straight up). The number afterward is the distance that the plane
is displaced along the normal from the origin -- in this case, the floor is placed at y=-1 so that the sphere at y=1,
radius=2, is resting on it.
Note: even though there is no texture statement there is an implied
texture here. We might find that continually typing statements that are nested like texture {pigment} can
get to be tiresome so POV-Ray let's us leave out the texture statement under many circumstances. In
general we only need the texture block surrounding a texture identifier (like the T_Stone25 example
above), or when creating layered textures (which are covered later).
This pigment uses the checker color pattern and specifies that the two colors red and blue should be used.
Because the vectors <1,0,0>, <0,1,0> and <0,0,1> are used frequently, POV-Ray has three built-in
vector identifiers x, y and z respectively that can be used as a shorthand.
Thus the plane could be defined as:
plane { y, -1
pigment { ... }
}
Note: that we do not use angle brackets around vector identifiers.
Looking at the floor, we notice that the ball casts a shadow on the floor. Shadows are calculated very accurately
by the ray-tracer, which creates precise, sharp shadows. In the real world, penumbral or "soft" shadows are
often seen. Later we will learn how to use extended light sources to
soften the shadows.
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