Purpose
Opcode format | Opcode | Operand Format | Comments |
Extended ASCII | (Layer | <ws><ILayerNum>[<ws><TLayerName>]) | Establishes which layer the following primitives will belong to. |
Single-byte binary operand | 0xAC | <BLayerNum>[<USElayernum>] | Establishes which layer the following primitives will belong to. |
Elayernum In the binary form, if the layer number is greater than 255, then LayerNum is stored as zero, and a two byte Elayernum follows indicating layer numbers from the range 256 to 65791.
LayerName An optional ASCII text string that names the layer number specified.
A layer attribute is attached to a specific set of opcodes by surrounding them with a pair of Set Layer opcodes: the first with a LayerNum specified and the second with a null LayerNum:
L 10,10 35,35 This line is attached to layer 1, the Electrical layer.
L 0,10 30,30 This
line is attached to layer 1, the Electrical layer.
By default all layers are on and thus visible. If it is desired that a layer be normally off (invisible), then a Set Layer State (TBD) opcode should proceed any geometric primitives contained in that layer.
Layers do not affect the drawing order of geometric primitives. It is possible to have two layers where some primitives of the first layer are drawn before some primitives of the second layer and vice versa. To accomplish this, return to a given layer after selecting another layer. For example, three lines are drawn in the order in which they appear in the file:
L 10,10 35,35 This line is attached to layer 1, the Electrical layer.
(Layer 2 Plumbing) Subsequent geometry uses layer 2.
L 0,20 20,20 This line is on layer 2, the Plumbing layer.
(Layer 1) Return to layer 1.
L 10,10 35,35 This
line is attached to layer 1, the Electrical layer.