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# what is a Prim?

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## Question

I was reading about mesh and land weight. What is a "Prim"?

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"Prim" is short for "geometric primitive"...the basic shapes that can be created with the Build tools right in Second Life, like a cube or a sphere.

Land can only support a certain number of prims.  After it reaches its capacity, the land parcel will not allow any other objects to be rezzed or brought in.

In the old days, all we worried about was prim count.  But with the advent of Mesh objects, a new way of accounting for objects had to be developed.  So now, a land parcel's ability to host objects is termed "parcel land capacity" and an object's "weight" is now called "land impact".  Land impact, or LI, may be the same as the number of prims in the object, but it may not.

Land impact of a simple cube is 1.  Land impact of a mesh object depends on the number of polygons in the object, its level of detail settings, its physical size, and its physics (collision) envelope.  For a discussion of how LI is calculated, see this link: https://community.secondlife.com/t5/English-Knowledge-Base/Calculating-land-impact/ta-p/974163

It's relatively easy to make a mesh object in a 3D modeling progam like Blender.  But tweaking that object so that it has the lowest possible LI and the highest possible visual quality can be a laborious process involving many test uploads.  It's a good idea to use the Beta grid to do this, since uploads don't cost anything there.  Only upload your mesh creation to the main grid after you are sure you have got everything right!

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Oh, my ..... let's see.....  Piecing together bits and pieces of basic information ....................

A primitive, or prim, is a single-part object, a basic native building block in Second Life.  Multi-part objects will have multiple parts ("prims").  Although an increasing number of objects these days are modeled outside of SL and imported as mesh creations, prims remain the foundation of much of the world you see.  They are easy for any resident to manipulate and build with, using only the tools in the SL viewer.

In Second Life, virtual physical objects such as cars, houses, jewelry, and even less obvious things like hair and clothing are made out of one or more prims. Objects made from prims are usually created in-world using the built-in object editing tool.

The color, texture, bumpiness, shininess, and transparency of prims can also be adjusted, and images (textures) can be applied to each surface (face/side) of a prim to change its appearance. Box, cylinder, and prism prim shape types can also be made flexible.

Prims can be linked together into link sets. They can also be attached to avatars.

Here's a classic Torley video  >>> http://wiki.secondlife.com/wiki/Video_Tutorial/What_is_a_prim%3F

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The shortest answer: A prim is a ready made building block. It comes in seven basic shapes and you can twist them and combine them to create an amazing number of different builds.

The prim was the original buiding material for Second Life and I believe even today most of what you see there are made from prims. Technically a prim is mesh, the only real difference is that the shapes are predefined.

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