Added reflection

Author: jphsd

.gitignore

@@ -1,5 +1,6 @@
 go.sum
 *.ngo
+*.nmod
 *.jpeg
 *.jpg
 

random.go

@@ -46,6 +46,7 @@ func GetNodes() []Node {
 			{"Combiner3", MakeCombiner3},
 			{"Displace", MakeDisplace},
 			{"VectorCombine", MakeVectorCombine},
+			{"Reflect", MakeReflect},
 		}
 	}
 	return NodeOptions
@@ -361,6 +362,14 @@ func MakeVectorCombine(md, d int) Field {
 	return &VectorCombine{MakeVectorField(md, d+1), MakeCombiner3Func(), MakeFilter()}
 }
 
+// MakeReflect creates a mirror plane in the field.
+func MakeReflect(md, d int) Field {
+	h, w := 600.0, 600.0
+	lp1 := []float64{rand.Float64() * w, rand.Float64() * h}
+	lp2 := []float64{rand.Float64() * w, rand.Float64() * h}
+	return NewReflect(MakeField(md, d+1), lp1, lp2)
+}
+
 // MakeNormal creates a new vector field from a field.
 func MakeNormal(md, d int) VectorField {
 	return NewNormal(MakeField(md, d), 10, 10, 2, 2)

reflect.go

@@ -0,0 +1,85 @@
+package texture
+
+import (
+	"github.com/jphsd/graphics2d"
+	"github.com/jphsd/graphics2d/util"
+	"image/color"
+)
+
+// Reflect contains a line along which a reflection is performed. The line defines where the
+// mirror is. Points on the + side of the line remain untransformed, points on the other are
+// reflected through the transformation.
+type Reflect struct {
+	Src   Field
+	Start []float64
+	End   []float64
+	Xfm   *graphics2d.Aff3
+}
+
+// NewReflect creates a new Reflection placing the mirror along lp1, lp2.
+func NewReflect(src Field, lp1, lp2 []float64) *Reflect {
+	xfm := graphics2d.NewAff3()
+	xfm.Reflect(lp1[0], lp1[1], lp2[0], lp2[1])
+	return &Reflect{src, lp1, lp2, xfm}
+}
+
+// Eval2 implements the Field interface.
+func (r *Reflect) Eval2(x, y float64) float64 {
+	pt := []float64{x, y}
+	if util.SideOfLine(r.Start, r.End, pt) < 0 {
+		pt = r.Xfm.Apply(pt)[0]
+	}
+	return r.Src.Eval2(pt[0], pt[1])
+}
+
+// ReflectVF contains a line along which a reflection is performed. The line defines where the
+// mirror is. Points on the + side of the line remain untransformed, points on the other are
+// reflected through the transformation.
+type ReflectVF struct {
+	Src   VectorField
+	Start []float64
+	End   []float64
+	Xfm   *graphics2d.Aff3
+}
+
+// NewReflect creates a new Reflection placing the mirror along lp1, lp2.
+func NewReflectVF(src VectorField, lp1, lp2 []float64) *ReflectVF {
+	xfm := graphics2d.NewAff3()
+	xfm.Reflect(lp1[0], lp1[1], lp2[0], lp2[1])
+	return &ReflectVF{src, lp1, lp2, xfm}
+}
+
+// Eval2 implements the Field interface.
+func (r *ReflectVF) Eval2(x, y float64) []float64 {
+	pt := []float64{x, y}
+	if util.SideOfLine(r.Start, r.End, pt) < 0 {
+		pt = r.Xfm.Apply(pt)[0]
+	}
+	return r.Src.Eval2(pt[0], pt[1])
+}
+
+// ReflectCF contains a line along which a reflection is performed. The line defines where the
+// mirror is. Points on the + side of the line remain untransformed, points on the other are
+// reflected through the transformation.
+type ReflectCF struct {
+	Src   ColorField
+	Start []float64
+	End   []float64
+	Xfm   *graphics2d.Aff3
+}
+
+// NewReflect creates a new Reflection placing the mirror along lp1, lp2.
+func NewReflectCF(src ColorField, lp1, lp2 []float64) *ReflectCF {
+	xfm := graphics2d.NewAff3()
+	xfm.Reflect(lp1[0], lp1[1], lp2[0], lp2[1])
+	return &ReflectCF{src, lp1, lp2, xfm}
+}
+
+// Eval2 implements the Field interface.
+func (r *ReflectCF) Eval2(x, y float64) color.Color {
+	pt := []float64{x, y}
+	if util.SideOfLine(r.Start, r.End, pt) < 0 {
+		pt = r.Xfm.Apply(pt)[0]
+	}
+	return r.Src.Eval2(pt[0], pt[1])
+}