Forum: Bryce
Subject: Intersect?
alvinylaya opened this issue on Apr 22, 2003 ยท 8 posts
alvinylaya posted Tue, 22 April 2003 at 12:32 PM
I pretty much got Negative and Positive attributes, I still don't understand "Intersect". What does it do? Does anyone ever use it? Any tutorials on this? Or maybe a simple explanation.
tjohn posted Tue, 22 April 2003 at 12:38 PM
Make 2 spheres. Move them together so that they overlap each other. Change their attributes to "intersect". Group them. The only thing that will show is where the spheres overlap or intersect. In the case of the 2 spheres you get a football shaped object. As for using it, I tried it out, but have never used it in an image.
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nuski posted Tue, 22 April 2003 at 2:15 PM
![](https://live.cdn.renderosity.com/forum/_legacy/file_55457.jpg)
By combining negative and intersect booleans, you can create a matching set of irregular shaped objects for use as i.e., cracked eggs or as I illustrated here . . . a simple separating effect. Create and group a positive and negative object. Here, I used a rectangle as the positive and the terrain as the negative object.. Duplicate the set and change the negative object of the duplication to intersect. You should now have matching portions of the original positive shape. Select and Shift select both the positive and negative booleans. Use the Align tool to center the objects. They should be a perfect match. Now you can select and reposition both objects as desired.
madmax_br5 posted Tue, 22 April 2003 at 4:15 PM
![](https://live.cdn.renderosity.com/forum/_legacy/file_55458.jpg)
Intersect is also very useful for joining the "skins" of primitive objects, especially useful for glass like the one above. There are two things i used intersect for. See the lightly curved lip on the top of the glass? That is 2 cones, one positive and one negative, AND a sphere resting just over the edge of the positive cone set to intersect. What it then does is render all faces within the sphere, and because a few of them were curved off by the placement of the sphere, the lip looks smoothly curved. I also used intersect for the stem of the glass. it is two cones, one upside down, both stretched to the same length. Now normally, you would see a bow tiew where they touch, but i set them to postive and made another sphere set to intersect. This way bryce only renders the outside faces, so the internal unwanted bowtie is circumvented.
Claymor posted Tue, 22 April 2003 at 4:43 PM
![](https://live.cdn.renderosity.com/forum/_legacy/file_55459.jpg)
Simplistic example:
I create two spheres, the larger positive, the smaller negative, in order to create a "hollow" ball.
I create two rectangles that intersect the spheres at right angles and set these to "intersect".
Group the whole thing.
The result is two circular bands, the place where the rectangles intersect the spheres.
I set THAT group to positive, cut it in half with a negative cube and I have the bands that I need for the top of the helmet started on the top left.
AgentSmith posted Tue, 22 April 2003 at 5:28 PM
Wow, NICE examples!
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alvinylaya posted Tue, 22 April 2003 at 10:20 PM
Whoa, Thanks thanks!!! These are awesome!
Doublecrash posted Tue, 22 April 2003 at 10:22 PM
![](https://live.cdn.renderosity.com/forum/_legacy/file_55460.jpg)
Whoa, Alvin... now that you will surely understand and use intersect, what will you achieve? I just can't believe that you did your MECHA I with only negative and positive booleans! That's amazing! Here's a very quick example. It's the same fridge I used in my "One For The Road" pic. I wanted it to be "fat" (dunno the right word in English, sorry), so I used a cube positive, subtracted the interior with a negative cube, then made the group positive and made it intersect with a large oblong sphere to achieve the "curved" result. Shelfs, glass and handle added after. Stefano