Mercurial > gemma
view pkg/octree/contours.go @ 1134:0420761c1c3f
Store contour lines in deterministic order.
author | Sascha L. Teichmann <sascha.teichmann@intevation.de> |
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date | Wed, 07 Nov 2018 21:45:10 +0100 |
parents | a244b18cb916 |
children | 064d44ccc6f2 |
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// This is Free Software under GNU Affero General Public License v >= 3.0 // without warranty, see README.md and license for details. // // SPDX-License-Identifier: AGPL-3.0-or-later // License-Filename: LICENSES/AGPL-3.0.txt // // Copyright (C) 2018 by via donau // – Österreichische Wasserstraßen-Gesellschaft mbH // Software engineering by Intevation GmbH // // Author(s): // * Sascha L. Teichmann <sascha.teichmann@intevation.de> package octree import ( "runtime" "sync" ) type ContourResult struct { Height float64 Lines MultiLineStringZ done bool mu sync.Mutex cond *sync.Cond } func NewContorResult(height float64) *ContourResult { cr := ContourResult{Height: height} cr.cond = sync.NewCond(&cr.mu) return &cr } func (cr *ContourResult) wait() { cr.cond.L.Lock() for !cr.done { cr.cond.Wait() } cr.cond.L.Unlock() } func (cr *ContourResult) get() float64 { cr.cond.L.Lock() defer cr.cond.L.Unlock() return cr.Height } func (cr *ContourResult) set(lines MultiLineStringZ) { cr.cond.L.Lock() defer cr.cond.L.Unlock() cr.Lines = lines cr.done = true cr.cond.Signal() } func DoContours(tree *Tree, step float64, store func(*ContourResult)) { var contours []*ContourResult for h := tree.Min.Z; h <= tree.Max.Z; h += step { contours = append(contours, NewContorResult(h)) } jobs := make(chan *ContourResult) var wg sync.WaitGroup for i, n := 0, runtime.NumCPU(); i < n; i++ { wg.Add(1) go processLevels(tree, jobs, &wg) } done := make(chan struct{}) go func() { defer close(done) for _, cr := range contours { cr.wait() store(cr) } }() for _, cr := range contours { jobs <- cr } close(jobs) wg.Wait() <-done } func processLevels( tree *Tree, jobs <-chan *ContourResult, wg *sync.WaitGroup, ) { defer wg.Done() for cr := range jobs { var lines MultiLineStringZ h := cr.get() tree.Horizontal(h, func(t *Triangle) { line := t.IntersectHorizontal(h) if len(line) > 1 { lines = append(lines, line) } }) cr.set(lines.Merge()) } }