There is another kind of transparency in POV-Ray. It is called transmittance or non-filtering transparency (the keyword is transmit ). It is different from filter in that it does not filter the light according to the pigment color. It instead allows all the light to pass through unchanged. It can be specified like this: rgbt<1, 0, 0, 1> .
Let's use some transparent pigments to create another kind of texture, the layered texture. Returning to our previous example, declare the following texture.
This texture will be the land area. Now let's make the oceans by declaring the following.
Note how the ocean is the opaque blue area, and the land is the clear area which will allow the underlying texture to show through.
Now, let's declare one more texture to simulate an atmosphere with swirling clouds.
Now apply all of these to our sphere.
Render this and you'll have a pretty good rendition of a little planetoid. But it could be better. We don't particularly like the appearance of the clouds. There is a way they could be done that would be much more realistic.
Add the following declarations, making sure they appear before the other declarations in the file.
Now use these declared pigments in our cloud layer on our planetoid. Replace the declared cloud layer with.
Render this and you'll see a remarkable pattern that looks very much like weather patterns on the planet earth. They are separated into bands, simulating the different weather types found at different latitudes.
Here we have added a normal block in addition to the pigment block (note that these do not have to be included in a texture block unless they need to be transformed together or need to be part of a layered texture). Render this to see what it looks like. Now, one at a time, substitute for the keyword bumps the following keyowrds: dents , wrinkles , ripples , and waves (you can also use any of the patterns listed in "Patterns" ). Render each to see what they look like. Play around with the float value that follows the keyword. Try experimenting with the scale value too.
For added interest, change the plane texture to a single color with a normal as follows.
As you can see, the resulting pattern is neither a radial nor a gradient. It is instead the result of first calculating a radial pattern and then calculating a gradient pattern. The results are simply additive. This can be difficult to control so POV-Ray gives the user other ways to blend normals.
One way is to use normal maps. A normal map works the same way as the pigment map we used earlier. Let's change our sphere texture as follows.
Rendering this we see that the sphere now has a very irregular bumpy surface. The gradient pattern type separates the normals into bands but they are turbulated, giving the surface a chaotic appearance. But this give us an idea.
Suppose we use the same pattern for a normal map that we used to create the oceans on our planetoid and applied it to the land areas. Does it follow that if we use the same pattern and modifiers on a sphere the same size that the shape of the pattern would be the same? Wouldn't that make the land areas bumpy while leaving the oceans smooth? Let's try it. First, let's render the two spheres side-by-side so we can see if the pattern is indeed the same. Un-comment the planetoid sphere and make the following changes.
Now change the gray sphere as follows.
Now render this to see if the pattern is the same. We see that indeed it is. So let's comment out the gray sphere and add the normal block it contains to the land area texture of our planetoid. Remove the transformations so that the planetoid is centered in the scene again.
Looking at the resulting image we see that indeed our idea works! The land areas are bumpy while the oceans are smooth. Add the cloud layer back in and our planetoid is complete.
There is much more that we did not cover here due to space constraints. On your own, you should take the time to explore slope_map , average , and bump_map .