Primitives Reference: Difference between revisions
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===Technic connector primitives=== | |||
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These primitives are used to contruct technic connector pegs. They are orientated with the technic axle hole along the {y} axis and must not be scaled. | |||
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| '''connect.dat''' || '''Technic connector - long with collar''' | |||
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|style="width: 200px;" |[[File:Connect.png|200px|thumb|alt=Connect]] | |||
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| '''connect2.dat''' || '''Technic connector - long without collar''' | |||
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| [[File:Connect2.png|200px|thumb|alt=Connect2]] | |||
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| '''connect3.dat''' || '''Technic connector - short with collar''' | |||
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| [[File:Connect3.png|200px|thumb|alt=Connect3]] | |||
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| '''connect4.dat''' || '''Technic connector - short without collar''' | |||
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| [[File:Connect4.png|200px|thumb|alt=Connect4]] | |||
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| '''connect5.dat''' || '''Technic connector - long with collar and slot''' | |||
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| [[File:Connect5.png|200px|thumb|alt=Connect5]] | |||
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| '''connect6.dat''' || '''Technic connector - long with collar and notches''' | |||
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| [[File:Connect6.png|200px|thumb|alt=Connect6]] | |||
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| '''connect7.dat''' || '''Technic connector - long with rectangular centre hole and thin (frictionless) ribs''' | |||
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| [[File:Connect7.png|200px|thumb|alt=Connect7]] | |||
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| '''connect8.dat''' || '''Technic connector - long with collar and blind hole''' | |||
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| [[File:Connect8.png|200px|thumb|alt=Connect8]] | |||
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| '''connect10.dat''' || '''Technic Pin 1.0 without Base Collar and Rectangular Centre Hole''' | |||
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| [[File:Connect10.png|200px|thumb|alt=Connect10]] | |||
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| '''connectcollar1.dat''' || '''Technic Pin Collar Half with Rectangular Hole and Short Slit''' | |||
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| [[File:Connectcollar1.png|200px|thumb|alt=Connectcollar1]] | |||
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| '''connectcollar2.dat''' || '''Technic Pin Collar Half with Small Rectangular Hole and Short Slit''' | |||
|- | |||
| [[File:Connectcollar2.png|200px|thumb|alt=Connectcollar2]] | |||
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| '''connectcollar3.dat''' || '''Technic Pin Collar Half with Rectangular Hole and Long Slit''' | |||
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| [[File:Connectcollar3.png|200px|thumb|alt=Connectcollar3]] | |||
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| '''connectcollar4.dat''' || '''Technic Pin Collar Half with Small Rectangular Hole and Long Slit''' | |||
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| [[File:Connectcollar4.png|200px|thumb|alt=Connectcollar4]] | |||
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| '''connectcollar5.dat''' || '''Technic Pin Collar Half with Round Hole and Short Slit''' | |||
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| [[File:Connectcollar5.png|200px|thumb|alt=Connectcollar5]] | |||
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| '''connectslit1.dat''' || '''Technic Pin Long Middle Slit Half with Rectangular Hole''' | |||
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| [[File:Connectslit1.png|200px|thumb|alt=Connectslit1]] | |||
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|- | |||
| '''connectslit2.dat''' || '''Technic Pin Long Middle Slit Half with Small Rectangular Hole''' | |||
|- | |||
| [[File:Connectslit2.png|200px|thumb|alt=Connectslit2]] | |||
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|} | |} | ||
Revision as of 13:43, 9 December 2023
LDraw Primitives Reference
This page is a source of reference for the LDraw primitives in the \LDraw\p directory. Primitives are defined as highly re-usable components of LEGO parts modelled for LDraw. They serve several purposes :
- To speed up parts authoring by providing a library of components which can be incorporated into several parts
- To allow rendering software to make substitutions of curved components
Within this reference material the available primitives are categorised into:
Each section contains an overview of the characteristics common to all primitives within that category. Primitives are grouped into classes within each category - one class of primitive serving a similar purpose at different sizes or resolutions. For each class of primitive, a brief description of the purpose of the primitive is provided, with notes on its co-ordinate origin, default size and rules for scaling. A list of the available primitives is shown.
An understanding of the orientation of the co-ordinate axes is essential for authoring a part for LDraw. For reference within this page the axes and their direction is shown in this diagram.
Rectilinear primitives
Nomenclature
Boxes are named boxF, with F representing the number of faces a box has. The suffix E represents the number of edges removed.
F and E are may followed by an additional letter. The hyphen is removed if F is accompanied by a modifier.
Face modifiers:
- o - faces are opposite to each other
- t - faces are all touching each other (usually, it's implied, but box4t.dat is a thing)
- u - missing faces form a U-shape
Edge letters:
- p - groups of edges are parallel to each other
- a - some missing faces have no adjacent edges
Scaling and orientation
These rectilinear elements may be scaled in the {x}, {y} and {z} dimensions to make elements of any size. For example
1 16 0 0 0 40 0 0 0 1 0 0 0 20 rect.dat
would generate a 80LDu x 40LDu rectangle in the {x,z} plane.
Although the default orientation of the rect.dat primitive is in the {x,z} plane the LDraw language allows for this to be transformed
1 16 0 0 0 0 1 0 40 0 0 0 0 20 rect.dat
would generate a 80LDu x 40LDu rectangle in the {y,z} plane.
1 16 0 0 0 40 0 0 0 0 20 0 1 0 rect.dat
would generate a 80LDu x 40LDu rectangle in the {x,y} plane.
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Curved primitives
LDraw represents curved surfaces as polygons. For circular components two series of primitives are provided.
All the circular primitives are orientated in the {x,z} plane with their origin at the centre of the circle and a default radius of 1 LDu. Primitives are provided for complete circles and for commonly used fractions of a complete circle. Where the naming convention includes a prefix of the form n-f this indicates the fraction (n/f) of the circle drawn by the primitive. Where this fraction is less than an entire circle, the primitive starts at {+x,0} and progresses in a conterclockwise direction when viewed from above {-y}.
To avoid rounding errors, it is preferable to use existing fractional circular primitives, or create a new primitive, rather than rotate an existing primitive by anything other than 90 or 180 degrees. For example, use 3-16XXXX.dat rather than combining 1-8XXXX.dat with 1-16XXXX.dat rotated by 22.5 degreees.
To avoid matrix arithmetic problems in some renderers, the third dimension ({y} in the default orientation) of two-dimensional primitives must be given a non-zero scaling factor. LDraw circles are normally formed of 16-sided polygons (hexdecagons) - the regular resolution. For larger elements, where scaling-up of hexadecagons would give too angular an appearance, a series of high resolution primitives based on a 48-sided polygon are available. These may also be used for parts not well suited to a 16-fold symmetry.
These circular elements may be scaled by the same factor in both the {x} and {z} dimensions to make circular elements of greater or less than 1LDu radius. For example
1 16 0 0 0 3 0 0 0 1 0 0 0 3 4-4edge.dat
would generate a circle in the {x,z} plane with a radius of 3LDu.
They may also be scaled asymmetrically in the x and z dimension to make ellipses.
Although the default orientation is in the {x,z} plane the LDraw language allows for these to be transformed
1 16 0 0 0 0 1 0 3 0 0 0 0 3 4-4edge.dat would generate a circle in the {y,z} plane
1 16 0 0 0 3 0 0 0 0 3 0 1 0 4-4edge.dat would generate a circle in the {x,y} plane
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Technic primitives
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