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Bryce Booleans

I sometimes have trouble getting Shape Magic objects to boolean correctly in Bryce. This tutorial will show you what to do.

The image below uses pillar09.obj from the column kit 1 sampler. The middle pillar is as it appears after importing into Bryce with a wood texture added. The other 4 pillars are duplicate of the center pillar booleaned with a cube.

After selecting a pillar, first click on the "U" box to ungroup them. Shape Magic objects have 5 parts: a top and bottom face and 3 segments. When imported into Bryce, all 5 parts are combined into one group. If you don't ungroup them, they won't boolean.

While the pillar parts are still selected, type the letter "p" to make all five parts boolean positive. Then create a box and position it to cut away a portion of the pillar. While the cube is still selected, type the letter "n" to make it boolean negative. Then select all five parts of the pillar as well as the cube and click on the "G' box to group them. This allows the negative box to cut away part of the positive pillar. The second pillar from the left shows what you get: a hollow pillar with part of the outer surface missing.

If you want the interior to be solid (as in the far right pillar) you have to select all parts of the pillar, click on the "E" box, then click on the "Solid When Boolean Rendering" so the check mark appears. Select all parts of the pillar and the cube, then click on the "G" box to group them.

This is where problems start. The pillar on the far left shows what you get.The three pillar segments and the end faces interfere with each other. Not good! Compare this to the last pillar on the right which shows the box correctly cutting away the pillar (I'll tell you how in a moment).

If  "Solid When Boolean Rendering" is not turned on, everything is OK. So for hollow objects, nothing special needs to be done but for solid objects, you have to eliminate the group names.

 

How do you eliminate group names? The easiest way is in Shape Magic itself. When saving the object, uncheck the "group Names" box underneath the text box where you type in the file name. See image below.

The harder way is to edit the .obj file. How to edit? Use Notepad or Wordpad to open  filename.obj. Use the find option and look for the letter "g". Each time you find it, delete the line it is in (for example, "g bottom_end_face"). This removes the grouping. Save the file.

Now import the modified file into Bryce. After selecting the pillar,  type the letter "p" to make it boolean positive. Click on the "E" box, then click on the "Solid When Boolean Rendering" so the check mark appears. Create another cube and position it to partially cut away part of the pillar. While the box is still selected, type the letter "n" to make it boolean negative. Finally, select the pillar and the cube and click on the "G" box to group them. This allows the negative box to cut away part of the positive pillar. The far right pillar in the image above shows that the interferences are now gone, just as we want.


Use for Booleans

This image shows one use for booleans. Pillars 13a and 13b from the .SMG Column Kit 1 were used. These pillars are identical except in one the protrusions twist to the left and in the other they twist to the right. When superimposed, you get an overlapping grid as shown on the left column (no booleans). The right column shows the same two pillars except a negative cylinder was used to cut out the middle with "Solid When Boolean Rendering" set to on. You now have a "cage".


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