SDF fixes (#126)

* SDF bug fixes
* minor perf improvements

Author: EliCDavis

generator/edit/examples/shapurr.json

@@ -80,6 +80,22 @@
             z-index: 1;
         }
 
+        #running-message {
+            display: none;
+            position: absolute;
+            right: 20px;
+            bottom: 20px;
+            padding: 10px;
+            box-sizing: border-box;
+            text-align: center;
+            -moz-user-select: none;
+            -webkit-user-select: none;
+            -ms-user-select: none;
+            user-select: none;
+            pointer-events: none;
+            z-index: 1;
+        }
+
         #messageContainer {
             position: absolute;
             left: 0px;
@@ -433,6 +449,9 @@
     <div id="watermark">
         <a href="https://github.com/EliCDavis/polyform">Polyform</a>
     </div>
+    <div id="running-message">
+        Running...
+    </div>
 
     <div id="messageContainer">
         <div id="infoMessage"> </div>

generator/edit/html/server.html

@@ -0,0 +1,34 @@
+package sdf
+
+import (
+	"github.com/EliCDavis/polyform/math/sample"
+	"github.com/EliCDavis/vector/vector3"
+)
+
+// func displacementExample(p vector3.Float64) float64 {
+// 	return math.Sin(20*p.X()) * math.Sin(20*p.Y()) * math.Sin(20*p.Z())
+// }
+
+func Displace(primitive, displacement sample.Vec3ToFloat, p vector3.Float64) float64 {
+	d1 := primitive(p)
+	d2 := displacement(p)
+	return d1 + d2
+}
+
+// func opTwist(primitive sample.Vec3ToFloat, p vector3.Float64) float64 {
+// 	const k = 10.0 // or some other amount
+// 	c := math.Cos(k * p.Y())
+// 	s := math.Sin(k * p.Y())
+// 	m := math.mat2(c, -s, s, c)
+// 	q := vector3.New(m*p.xz, p.Y())
+// 	return primitive(q)
+// }
+
+// func opCheapBend(primitive sample.Vec3ToFloat, p vector3.Float64) float64 {
+// 	const k = 10.0 // or some other amount
+// 	c := math.Cos(k * p.X())
+// 	s := math.Sin(k * p.X())
+// 	m := math.mat2(c, -s, s, c)
+// 	q := vector3.New(m*p.xy, p.Z())
+// 	return primitive(q)
+// }

math/sdf/art.go

@@ -1,8 +1,6 @@
 package sdf
 
 import (
-	"math"
-
 	"github.com/EliCDavis/polyform/math/geometry"
 	"github.com/EliCDavis/polyform/math/sample"
 	"github.com/EliCDavis/polyform/nodes"
@@ -25,9 +23,7 @@ func MultipointLine(points []vector3.Float64, radius float64) sample.Vec3ToFloat
 
 	switch len(points) {
 	case 0:
-		return func(f vector3.Float64) float64 {
-			return math.Inf(1)
-		}
+		return nullField
 
 	case 1:
 		return Sphere(points[0], radius)

math/sdf/line.go

@@ -11,6 +11,7 @@ func init() {
 
 	refutil.RegisterType[nodes.Struct[TranslateNode]](factory)
 	refutil.RegisterType[nodes.Struct[TransformNode]](factory)
+	refutil.RegisterType[nodes.Struct[RepeatNode]](factory)
 
 	refutil.RegisterType[nodes.Struct[UnionNode]](factory)
 	refutil.RegisterType[nodes.Struct[IntersectionNode]](factory)

math/sdf/nodes.go

@@ -0,0 +1,43 @@
+package sdf
+
+import (
+	"github.com/EliCDavis/polyform/math/sample"
+	"github.com/EliCDavis/polyform/math/trs"
+	"github.com/EliCDavis/polyform/nodes"
+	"github.com/EliCDavis/vector/vector3"
+)
+
+func Repeat(field sample.Vec3ToFloat, transforms []trs.TRS) sample.Vec3ToFloat {
+	if len(transforms) == 0 {
+		return nullField
+	}
+
+	invertedTRS := make([]trs.TRS, len(transforms))
+	for i, v := range transforms {
+		invertedTRS[i] = trs.FromMatrix(v.Matrix().Inverse())
+	}
+
+	return func(v vector3.Float64) float64 {
+		closestPoint := field(invertedTRS[0].Transform(v))
+		for i := 1; i < len(invertedTRS); i++ {
+			closestPoint = min(closestPoint, field(invertedTRS[i].Transform(v)))
+		}
+		return closestPoint
+	}
+}
+
+type RepeatNode struct {
+	Transforms nodes.Output[[]trs.TRS]
+	Field      nodes.Output[sample.Vec3ToFloat]
+}
+
+func (cn RepeatNode) Result(out *nodes.StructOutput[sample.Vec3ToFloat]) {
+	if cn.Field == nil {
+		return
+	}
+
+	out.Set(Repeat(
+		nodes.GetOutputValue(out, cn.Field),
+		nodes.TryGetOutputValue(out, cn.Transforms, []trs.TRS{trs.Identity()}),
+	))
+}

math/sdf/repeat.go

@@ -32,8 +32,9 @@ func (cn TranslateNode) Result(out *nodes.StructOutput[sample.Vec3ToFloat]) {
 // <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
 
 func Transform(field sample.Vec3ToFloat, transformation trs.TRS) sample.Vec3ToFloat {
+	inverse := transformation.Inverse()
 	return func(v vector3.Float64) float64 {
-		return field(transformation.Transform(v))
+		return field(inverse.Transform(v))
 	}
 }
 

math/sdf/translate.go

@@ -0,0 +1,12 @@
+package sdf
+
+import (
+	"math"
+
+	"github.com/EliCDavis/vector/vector3"
+)
+
+// Field meant to represent "nothing".
+func nullField(f vector3.Float64) float64 {
+	return math.Inf(1)
+}

math/sdf/util.go

@@ -117,6 +117,10 @@ func (trs TRS) Multiply(other TRS) TRS {
 	return FromMatrix(trs.Matrix().Multiply(other.Matrix()))
 }
 
+func (trs TRS) Inverse() TRS {
+	return FromMatrix(trs.Matrix().Inverse())
+}
+
 // Transform an array of points by the TRS
 func (trs TRS) TransformArray(in []vector3.Float64) []vector3.Float64 {
 	out := make([]vector3.Float64, len(in))

math/trs/trs.go

@@ -31,7 +31,8 @@ func interpolateV1(v1, v2, t float64) float64 {
 
 func interpolateVerts(v1, v2 vector3.Float64, v1v, v2v, cutoff float64) vector3.Float64 {
 	t := interpolationValueFromCutoff(v1v, v2v, cutoff)
-	return v2.Sub(v1).Scale(t).Add(v1)
+	// return v2.Sub(v1).Scale(t).Add(v1)
+	return v1.Scale(1 - t).Add(v2.Scale(t))
 }
 
 func lookupOrAdd(data *workingData, vert vector3.Float64) int {
@@ -628,17 +629,18 @@ func (d *MarchingCanvas) marchFloat1BlockPosition(
 					lookupIndex |= 128
 				}
 
-				for i := 0; triangulation[lookupIndex][i] != -1; i += 3 {
+				tris := triangulation[lookupIndex]
+				for i := 0; tris[i] != -1; i += 3 {
 					// Get indices of corner points A and B for each of the three edges
 					// of the cube that need to be joined to form the triangle.
-					a0 := cornerIndexAFromEdge[triangulation[lookupIndex][i]]
-					b0 := cornerIndexBFromEdge[triangulation[lookupIndex][i]]
+					a0 := cornerIndexAFromEdge[tris[i]]
+					b0 := cornerIndexBFromEdge[tris[i]]
 
-					a1 := cornerIndexAFromEdge[triangulation[lookupIndex][i+1]]
-					b1 := cornerIndexBFromEdge[triangulation[lookupIndex][i+1]]
+					a1 := cornerIndexAFromEdge[tris[i+1]]
+					b1 := cornerIndexBFromEdge[tris[i+1]]
 
-					a2 := cornerIndexAFromEdge[triangulation[lookupIndex][i+2]]
-					b2 := cornerIndexBFromEdge[triangulation[lookupIndex][i+2]]
+					a2 := cornerIndexAFromEdge[tris[i+2]]
+					b2 := cornerIndexBFromEdge[tris[i+2]]
 
 					v1 := interpolateVerts(cubeCornerPositions[a0], cubeCornerPositions[b0], cubeCorners[a0], cubeCorners[b0], cutoff).Add(offset)
 					v2 := interpolateVerts(cubeCornerPositions[a1], cubeCornerPositions[b1], cubeCorners[a1], cubeCorners[b1], cutoff).Add(offset)