Mercurial > gemma

comparison pkg/octree/contours.go @ 976:c397fdd8c327

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Generate the contour lines of the sounding result during the import, too.
author Sascha L. Teichmann <sascha.teichmann@intevation.de>
date Thu, 18 Oct 2018 17:05:54 +0200
parents
children 4a2ca0e20006
comparison
equal deleted inserted replaced
975:3da707172772 976:c397fdd8c327
1 package octree
2
3 import (
4 "database/sql"
5 "runtime"
6 "sync"
7 )
8
9 const (
10 contourStepWidth = 0.5
11 contourTolerance = 0.1
12 )
13
14 type contourResult struct {
15 height float64
16 lines MultiLineStringZ
17 }
18
19 const (
20 insertContourSQL = `
21 INSERT INTO waterway.sounding_results_contour_lines (
22 sounding_result_id,
23 height,
24 lines
25 )
26 SELECT
27 $1,
28 $2,
29 ST_Transform(
30 ST_Multi(
31 ST_CollectionExtract(
32 ST_Intersection(
33 ST_Transform(sr.area::geometry, $3::integer),
34 ST_SimplifyPreserveTopology(
35 ST_GeomFromWKB($4, $3::integer),
36 $5
37 )
38 ),
39 2
40 )
41 ),
42 4326
43 )
44 FROM waterway.sounding_results sr
45 WHERE id = $1
46 `
47 )
48
49 func generateContours(tree *Tree, tx *sql.Tx, id int64) error {
50 stmt, err := tx.Prepare(insertContourSQL)
51 if err != nil {
52 return err
53 }
54 defer stmt.Close()
55
56 doContours(tree, contourStepWidth, func(res *contourResult) {
57 if err == nil {
58 _, err = stmt.Exec(
59 id, res.height, tree.EPSG,
60 res.lines.AsWKB2D(),
61 contourTolerance)
62 }
63 })
64
65 return err
66 }
67
68 func doContours(tree *Tree, step float64, store func(*contourResult)) {
69
70 results := make(chan *contourResult)
71 done := make(chan struct{})
72 jobs := make(chan float64)
73
74 go func() {
75 for {
76 select {
77 case r := <-results:
78 store(r)
79 case <-done:
80 return
81 }
82 }
83 }()
84
85 var wg sync.WaitGroup
86 for i, n := 0, runtime.NumCPU(); i < n; i++ {
87 wg.Add(1)
88 go processLevels(tree, jobs, results, &wg)
89 }
90 for h := tree.Min.Z; h <= tree.Max.Z; h += step {
91 jobs <- h
92 }
93 close(jobs)
94 wg.Wait()
95 done <- struct{}{}
96 }
97
98 func processLevels(
99 tree *Tree,
100 jobs <-chan float64,
101 results chan<- *contourResult,
102 wg *sync.WaitGroup,
103 ) {
104 defer wg.Done()
105 for h := range jobs {
106 var lines MultiLineStringZ
107 tree.Horizontal(h, func(t *Triangle) {
108 line := t.IntersectHorizontal(h)
109 if len(line) > 1 {
110 lines = append(lines, line)
111 }
112 })
113 lines = lines.Merge()
114 results <- &contourResult{h, lines}
115 }
116 }