line poly intersect should gove closest point if intersection hits two edges

This commit is contained in:
Fraser Graham 2013-11-25 21:13:22 -08:00
parent 6170691eb1
commit 0559630cc6
3 changed files with 37 additions and 4 deletions

View File

@ -1,5 +1,9 @@
package govector package govector
import (
"math"
)
func Intersection(p1, p2 Point2d, v1, v2 Vector2d) (bool, Point2d) { func Intersection(p1, p2 Point2d, v1, v2 Vector2d) (bool, Point2d) {
t := p2.Sub(p1).Cross(v2) / v1.Cross(v2) t := p2.Sub(p1).Cross(v2) / v1.Cross(v2)
s := p2.Sub(p1).Cross(v1) / v1.Cross(v2) s := p2.Sub(p1).Cross(v1) / v1.Cross(v2)
@ -63,19 +67,30 @@ func ProjectPolygon(axis Vector2d, p Polygon2d) (min float32, max float32) {
func PolygonIntersection(r Polygon2d, p Point2d, v Vector2d) (bool, Point2d) { func PolygonIntersection(r Polygon2d, p Point2d, v Vector2d) (bool, Point2d) {
// TODO - need to test point in polygon for start and end to detect wholly
// inside situations
intersection := false
i_point := Point2d{}
distance_sq := float32(math.MaxFloat32)
for point, _ := range r.Points { for point, _ := range r.Points {
if point == len(r.Points) { if point == len(r.Points) {
break break
} }
edgePt, edgeVec := r.Edge(point) edgePt, edgeVec := r.Edge(point)
intersection, pt := Intersection(p, edgePt, v, edgeVec) i, pt := Intersection(p, edgePt, v, edgeVec)
if intersection { if i {
return intersection, pt intersection = true
d_sq := pt.Sub(p).MagSquared()
if d_sq < distance_sq {
i_point = pt
distance_sq = d_sq
}
} }
} }
return false, Point2d{} return intersection, i_point
} }
func PolyPolyIntersection(p1 Polygon2d, v1 Vector2d, p2 Polygon2d, v2 Vector2d) bool { func PolyPolyIntersection(p1 Polygon2d, v1 Vector2d, p2 Polygon2d, v2 Vector2d) bool {

View File

@ -286,3 +286,17 @@ func TestPolyIntersectFail(t *testing.T) {
t.Errorf("PolyIntersect Error") t.Errorf("PolyIntersect Error")
} }
} }
func TestPolyIntersectTwoHits(t *testing.T) {
p1 := Polygon2d{}
p1.Points = append(p1.Points, Vector2d{0, 0})
p1.Points = append(p1.Points, Vector2d{0, 10})
p1.Points = append(p1.Points, Vector2d{10, 10})
p1.Points = append(p1.Points, Vector2d{10, 0})
i, p := PolygonIntersection(p1, Point2d{-1, 5}, Vector2d{20, 0})
if !i || (p.X != 0 && p.Y != 5) {
fmt.Printf("%v", p)
t.Errorf("PolyIntersect Error")
}
}

View File

@ -51,6 +51,10 @@ func (v Vector2d) Mag() float32 {
return float32(math.Abs(math.Sqrt(float64(v.X*v.X) + float64(v.Y*v.Y)))) return float32(math.Abs(math.Sqrt(float64(v.X*v.X) + float64(v.Y*v.Y))))
} }
func (v Vector2d) MagSquared() float32 {
return float32(math.Abs(float64(v.X*v.X) + float64(v.Y*v.Y)))
}
func (v Vector2d) PopPop() float32 { func (v Vector2d) PopPop() float32 {
return v.Mag() return v.Mag()
} }