"Merrin Cullen" <tim### [at] wohrrcom> wrote:
> Prodan,
>
> Actually, difference is working just fine. Here are some problems you are
> wrestling with.
>
> 1. The light is not in a position to light up the holes you are creating.
> Move one of your lights to the same position as your camera & you will be
> able to see the holes you are creating.
> 2. When in the process of developing an object, I frequently temporarily
> change the color of the hole to one that contrasts with the objects color.
> This helps me to see the the effects of the CSG operation.
> 3. When using CSG to create a hole, the shape used to create the hole must
> extend past the surface of the original object. If the shape does not extend
> past the surface of the original object, you have only created a hole inside
> the original object that can not be seen unless it is exposed by other
> holes.
> 4. Avoid coincident surfaces. For instance the shape box { <0, 0, 0>, <6,
> 53, 36> }and the shape box { <0, 0, 34>, <6, 51, 36> }both share common
> sides on every side except in the +y  and +z directions. POV Ray will become
> confused when mulitple shapes share a surface, this becomes more apparent
> when the shapes have different pigments or textures. How to avoid coincicent
> surfaces? Make sure one shape is slightly smaller or larger thatn the other
> shape. (See #1 above)
> 5. Your camera is not in the best position to see many of the holes you are
> trying to create.
>
> I have attached a rendering of your image with the one of the lights
> relocated to your camera position. Notice taht you can now see that some
> material has been removed by your difference CSG. You can also see speckled
> artifacts on some interior surfaces. These are caused by the coincidence
> surfaces.
>
> These are the same types of issues I faced when I first started with POV
> Ray. Welcome to the learning curve!
>
> Tim

I'm still having trouble creating it. How can one create stairs?

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