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use cross to implement

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Justin Lin
2019-05-28 14:24:10 +08:00
parent 00dfbd2366
commit 599ffdb4ab
1 changed files with 9 additions and 13 deletions
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22
src/bijection_offset.scad
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@@ -40,23 +40,19 @@ function _bijection__bijection_offset_edges(edges, d) =
)
_bijection_offset_edge(edge, dx, dy)
];
function _bijection__bijection__bijection_offset_edges_intersection(edge1, edge2) =
let(
den = (edge2[1][1] - edge2[0][1]) * (edge1[1][0] - edge1[0][0]) - (edge2[1][0] - edge2[0][0]) * (edge1[1][1] - edge1[0][1])
a1 = edge1[0],
a2 = edge1[1],
b1 = edge2[0],
b2 = edge2[1],
a = a2 - a1,
b = b2 - b1,
s = b1 - a1
)
// when den is 0, they are parallel or conincident edges
den == 0 ? [] : _bijection_offset__bijection__bijection__bijection_offset_edges_intersection_sub(edge1, edge2, den);
function _bijection_offset__bijection__bijection__bijection_offset_edges_intersection_sub(edge1, edge2, den) =
let(
ua = ((edge2[1][0] - edge2[0][0]) * (edge1[0][1] - edge2[0][1]) - (edge2[1][1] - edge2[0][1]) * (edge1[0][0] - edge2[0][0])) / den
)
[
edge1[0][0] + ua * (edge1[1][0] - edge1[0][0]),
edge1[0][1] + ua * (edge1[1][1] - edge1[0][1])
];
cross(a, b) == 0 ? [] : // they are parallel or conincident edges
a1 + a * cross(s, b) / cross(a, b);
function bijection_offset(pts, d) =
let(