Difference between revisions of "Prims"

Latest revision as of 00:43, 2 October 2009

This article is about primitives. For LSL related information, see Category:LSL Prim.

Introduction

This page is mostly about how primitives are implemented in the server and viewer code. It might help users of the in-world build tool understand the use of the many options. An excellent detailed summary can be found here. [1]

Primitives in Second Life are constructed by starting with a basic two dimensional shape, modifying it, and extruding it in to the third dimension along a path while applying modifications to the extrusion. The most basic example is a cube which starts out as a 2D square and extrudes along a linear path with no modifications to make a cube. A cylinder starts out as as circle and extrudes along the same linear path. If the circle was extruded along a circular path you would create a torus, and if a half-circle is extruded along another type of circular path you create a sphere.

2D Shape (Profile)

ProfileCurve
- Two combined enums: the lower 4 bits define the outer profile shape, and the high 4 bits define the type of hole if ProfileHollow is non-zero

Profile Shape:
Circle = 0x00
Square = 0x01
Isometric Triangle = 0x02
Equilateral Triangle = 0x03
Right Triangle = 0x04
Half Circle = 0x05

Hole Shape:
Same = 0x00
Circle = 0x10
Square = 0x20
Triangle = 0x30

2D Shape (Profile) Modifications

ProfileBegin
- Where the cut (if any) in the profile begins
ProfileEnd
- Where the cut (if any) in the profile ends
ProfileHollow
- How much of the profile is hollowed out, as a percent of the original bounding box. If non-zero this creates a hole using the shape defined in the higher bits of ProfileCurve

Extrusion (Path)

PathCurve
- Enum for the extrusion path. For whatever reason only the upper bits are used in this field:

Line = 0x10
Circle = 0x20
Circle2 = 0x30
Test = 0x40 // ???
Flexible = 0x80

Extrusion (Path) Modifications

PathBegin
PathEnd
PathScaleX
PathScaleY
PathShearX
PathShearY
PathTwistBegin
PathTwist
PathRadiusOffset
PathTaperX
PathTaperY
PathRevolutions
PathSkew

@@ Line 1: / Line 1: @@
-Primitives in Second Life are constructed by starting with a basic two dimensional shape, modifying it, and extruding it in to the third dimension along a path while applying modifications to the extrusion. The most basic example is a cube which starts out as a 2D square and extrudes along a linear path with no modifications to make a cube. A cylinder starts out as as circle and extrudes along the same linear path. If the circle was extruded along a circular path you would create a ring, and if a half-circle is extruded along another type of circular path you create a sphere.
+{{Otheruses4‎|primitives|[[LSL]] related information|:Category:LSL Prim}}
+==Introduction==
+This page is mostly about how primitives are implemented in the server and viewer code.  It might help users of the in-world build tool understand the use of the many options.  An excellent detailed summary can be found here. [http://www.realityprime.com/articles/how-sl-primitives-really-work]
+Primitives in Second Life are constructed by starting with a basic two dimensional shape, modifying it, and extruding it in to the third dimension along a path while applying modifications to the extrusion. The most basic example is a cube which starts out as a 2D square and extrudes along a linear path with no modifications to make a cube. A cylinder starts out as as circle and extrudes along the same linear path. If the circle was extruded along a circular path you would create a torus, and if a half-circle is extruded along another type of circular path you create a sphere.
 ==2D Shape (Profile)==
 * ProfileCurve
+** Two combined enums: the lower 4 bits define the outer profile shape, and the high 4 bits define the type of hole if ProfileHollow is non-zero
+<pre>
+Profile Shape:
+Circle = 0x00
+Square = 0x01
+Isometric Triangle = 0x02
+Equilateral Triangle = 0x03
+Right Triangle = 0x04
+Half Circle = 0x05
+</pre>
+<pre>
+Hole Shape:
+Same = 0x00
+Circle = 0x10
+Square = 0x20
+Triangle = 0x30
+</pre>
 ===2D Shape (Profile) Modifications===
 * ProfileBegin
+** Where the cut (if any) in the profile begins
 * ProfileEnd
+** Where the cut (if any) in the profile ends
 * ProfileHollow
+** How much of the profile is hollowed out, as a percent of the original bounding box. If non-zero this creates a hole using the shape defined in the higher bits of ProfileCurve
 ==Extrusion (Path)==
 * PathCurve
+** Enum for the extrusion path. For whatever reason only the upper bits are used in this field:
+<pre>
+Line = 0x10
+Circle = 0x20
+Circle2 = 0x30
+Test = 0x40 // ???
+Flexible = 0x80
+</pre>
 ===Extrusion (Path) Modifications===