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Mike Williams wrote:
> I suggest that you go back to my hole tutorial page and
> read it more carefully this time. Then try the following:-
>
Sorry -- actually the code posted was as exactly as it stood before I started
the whole thread. I make no pretense that I've yet gotten around to visiting
your hole tutorial page. :-)
Thanks for your input! --
I will try your suggestions, and compare them to Shay's macro, once I can get
some free time to look at them both. (I'm at work now -- gotta' work!
Perhaps as a "Gentleman of Leisure" this is a mundane consideration for you!
;-) )
>
> 1. Make sure that automatic bounding is happening, and then render both
> versions with the bounding slabs displayed ( use the +UD switch).
> Observe that there's a single slab for the whole of the object.
>
> 2. From the first inter_arc, comment out the "difference {" and the
> lines
> }
> cylinder { <-0.4, 0, -0.0101>, <-0.4, 0, 0.301> 1
> texture {T_Grnt19b }}
> cylinder { <-0.4, 0, -0.0101>, <-0.4, 0, 0.301> 1
> texture {T_Grnt19b } translate x*2.4 }
> leaving just the brick wall without the arch cur outs, and render this
> with +UD. Observe that each brick now has its own little bounding box,
> that the number of box tests logged in the stats has reduced by a factor
> of about 200, and that the thing renders very much faster.
>
> 3. Try cutting out the arch cylinders from each row of bricks. You
> should be able to gain much of the bounding improvement. My code for
> doing this looks like this:
>
> #declare arch = union {
> cylinder { <-0.4, 0, -0.0101>, <-0.4, 0, 0.301> 1}
> cylinder { <-0.4, 0, -0.0101>, <-0.4, 0, 0.301> 1 translate x*2.4 }
> }
>
> #declare inter_arc = union {
> difference {object { Row_Odd } object {arch}}
> difference {object { Row_Even } object {arch}}
> difference {object { Row_Odd translate y*0.16 } object {arch}}
> difference {object { Row_Even translate y*0.16 } object {arch}}
> difference {object { Row_Odd translate y*0.24 } object {arch}}
> difference {object { Row_Even translate y*0.24 } object {arch}}
> difference {object { Row_Odd translate y*0.32 } object {arch}}
> difference {object { Row_Even translate y*0.32 } object {arch}}
> difference {object { Row_Odd translate y*0.40 } object {arch}}
> difference {object { Row_Even translate y*0.40 } object {arch}}
> difference {object { Row_Odd translate y*0.48 } object {arch}}
> difference {object { Row_Even translate y*0.48 } object {arch}}
> difference {object { Row_Odd translate y*0.56 } object {arch}}
> difference {object { Row_Even translate y*0.56 } object {arch}}
> difference {object { Row_Odd translate y*0.64 } object {arch}}
> difference {object { Row_Even translate y*0.64 } object {arch}}
> difference {object { Row_Odd translate y*0.72 } object {arch}}
> difference {object { Row_Even translate y*0.72 } object {arch}}
> difference {object { Row_Odd translate y*0.8 } object {arch}}
> difference {object { Row_Even translate y*0.8 } object {arch}}
> difference {object { Row_Odd translate y*0.96 } object {arch}}
> difference {object { Row_Even translate y*0.96 } object {arch}}
> difference {object { Row_Odd translate y*1.04 } object {arch}}
> difference {object { Row_Odd translate y*1.04 } object {arch}}
> texture {T_Grnt19b}
> }
>
> Which only gives a 20 fold decrease in the number of box tests (because
> there's only one bounding slab per row, instead of one per brick) and
> results in a 5 fold speed increase.
>
> 4. for real speed (and coding simplicity) use a #while loop to place
> each individual brick, and difference the arch cutouts from each brick.
> That way you get a bounding slab for each brick.
> You might think that there would be an overhead from performing lots of
> unnecessary differences, but you're actually already telling POV to do
> all those difference operations anyway, they're just buried inside the
> unions.
>
> --
> Mike Williams
> Gentleman of Leisure
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