绘制行
看看你是否能理解以下函数。将其与伪代码进行比较，并尝试捕获刚才描述的几何计算。您可能不熟悉一些 AutoLISP 函数，如果您需要有关这些函数的帮助，请参阅 AutoLISP 文档。现在，只需阅读代码;不要写任何东西。 (defun gp:Calculate-and-Draw-Tiles (BoundaryData / PathLength
TileSpace TileRadius SpaceFilled SpaceToFill
RowSpacing offsetFromCenter
rowStartPoint pathWidth pathAngle
ObjectCreationStyle TileList)
(setq PathLength (cdr (assoc 41 BoundaryData))
TileSpace (cdr (assoc 43 BoundaryData))
TileRadius (cdr (assoc 42 BoundaryData))
SpaceToFill (- PathLength TileRadius)
RowSpacing (* (+ TileSpace (* TileRadius 2.0))
(sin (Degrees->Radians 60))
) ;_ end of *
SpaceFilled RowSpacing
offsetFromCenter 0.0
offsetDistance (/ (+ (* TileRadius 2.0) TileSpace) 2.0)
rowStartPoint (cdr (assoc 10 BoundaryData))
pathWidth (cdr (assoc 40 BoundaryData))
pathAngle (cdr (assoc 50 BoundaryData))
ObjectCreationStyle (strcase (cdr (assoc 3 BoundaryData)))
) ;_ end of setq
;; Compensate for the first call to gp:calculate-Draw-tile Row
;; in the loop below.
(setq rowStartPoint
(polar rowStartPoint
(+ pathAngle pi)
(/ TileRadius 2.0)
) ;_ end of polar
) ;_ end of setq
;; Draw each row of tiles.
(while (<= SpaceFilled SpaceToFill)
;; Get the list of tiles created, adding them to our list.
(setq tileList (append tileList
(gp:calculate-Draw-TileRow
(setq rowStartPoint
(polar rowStartPoint
pathAngle
RowSpacing
) ;_ end of polar
) ;_ end of setq
TileRadius
TileSpace
pathWidth
pathAngle
offsetFromCenter
ObjectCreationStyle
) ;_ end of gp:calculate-Draw-TileRow
) ;_ end of append
;; Calculate the distance along the path for the next row.
SpaceFilled (+ SpaceFilled RowSpacing)
;; Alternate between a zero and a positive offset
;; (causes alternate rows to be indented).
offsetFromCenter
(if (= offsetFromCenter 0.0)
offsetDistance
0.0
) ;_ end of if
) ;_ end of setq
) ;_ end of while
;; Return the list of tiles created.
tileList
) ;_ end of defun
代码中的几个部分可能需要一些额外的解释。 在循环开始之前，将出现以下代码片段：while ;; Compensate for the very first start point!! (setq rowStartPoint(polar rowStartPoint (+ pathAngle pi)(/ TileRadius 2.0))) 弄清楚这个算法背后的逻辑有三个部分：
为了补偿绘制第一行（即通过循环的第一个循环）期间的初始前移，您需要向相反方向稍微移动。目的是避免在路径边界和第一行之间出现大面积的空白空间。一半是足以移动点的量。这可以通过沿矢量方向投影来实现，该矢量方向与 .如果您考虑一下，这会将点暂时置于路径边界之外。rowStartPointwhilerowStartPointTileRadiuspolarrowStartPointPathAngle 下一个片段（为便于阅读而修改）可能有点令人费解： (setq tileList (append tileList
(gp:calculate-Draw-TileRow
(setq rowStartPoint
(polar rowStartPoint pathAngle RowSpacing)
) ;_ end of setq
TileRadius TileSpace pathWidth pathAngle
offsetFromCenter ObjectCreationStyle
))
)
从本质上讲，存在着一个缠绕着的调用。setqappendgp:calculate-Draw-TileRow 该函数将返回绘制的每个图块的对象 ID。（对象 ID 指向图形中的切片对象。您正在逐行绘制图块，因此该函数一次返回一行的对象 ID。该函数将新的对象 ID 添加到存储在 中的任何现有对象 ID 中。gp:calculate-Draw-TileRowappendtileList ; Near the end of the function, you can find the following code fragment:
(setq offsetFromCenter
(if (= offsetFromCenter 0.0)
offsetDistance
0.0
)
)
这是偏移切换开关，它确定正在绘制的行是应以路径为中心的圆开始，还是应从路径偏移开始。此算法的伪代码如下： ; Set the offset amount to the following: ; If the offset is currently zero, set it to the offset distance; ; Otherwise, set it back to zero. |
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