move dual contour stuff around

.gitignore

@@ -1,6 +1,7 @@
 # Go workspaces.
 go.work
 go.work.sum
+!examples/_dualcontour/go.work
 # Test binary, built with `go test -c`
 *.test
 # Dependency directories after running `go mod vendor`

glrender/dual_contour.go

@@ -8,12 +8,6 @@ import (
 	"github.com/soypat/gsdf/gleval"
 )
 
-type DualContourer interface {
-	// PlaceVertices should edit the FinalVertex field of all [DualCube]s in the cubes buffer.
-	// These resulting vertices are then used for quad/triangle meshing.
-	PlaceVertices(cubes []DualCube, origin ms3.Vec, res float32, sdf gleval.SDF3, posbuf []ms3.Vec, distbuf []float32, userData any) error
-}
-
 type DualContourRenderer struct {
 	sdf       gleval.SDF3
 	contourer DualContourer
@@ -201,6 +195,7 @@ func makeDualCube(ivec ivec, data []float32) DualCube {
 
 // DualCube corresponds to a voxel anmd contains both cube and edge data.
 type DualCube struct {
+	// ivec stores the octree index of the cube, used to find neighboring cube ivec indices and the absolute position of the cube.
 	ivec ivec
 	// Neighbors contains neighboring index into dualCube buffer and contributing edge intersect axis.
 	//  - Neighbors[0]: Index into dualCube buffer to cube neighbor with edge.
@@ -209,22 +204,15 @@ type DualCube struct {
 	Neighbors [][3]int
 	// Distance from cube origin to SDF.
 	OrigDist float32
-	// Distance from (x,y,z) edge vertices to SDF.
+	// Distance from (x,y,z) edge vertices to SDF. These edges are coincident with cube origin.
 	XDist, YDist, ZDist float32
-	// FinalVertex set by vertex strategy. Decides the final resting place of the vertex of the cube
+	// FinalVertex set by vertex placement strategy. Decides the final resting place of the vertex of the cube
 	// which will be the vertex meshed.
 	FinalVertex ms3.Vec
 }
 
-func vertMean(verts []ms3.Vec) (mean ms3.Vec) {
-	for i := 0; i < len(verts); i++ {
-		mean = ms3.Add(mean, verts[i])
-	}
-	return ms3.Scale(1./float32(len(verts)), mean)
-}
-
-func (dc *DualCube) SizeAndOrigin(res float32, modelOrigin ms3.Vec) (float32, ms3.Vec) {
-	return res, icube{ivec: dc.ivec, lvl: 1}.origin(modelOrigin, res)
+func (dc *DualCube) SizeAndOrigin(res float32, octreeOrigin ms3.Vec) (float32, ms3.Vec) {
+	return res, icube{ivec: dc.ivec, lvl: 1}.origin(octreeOrigin, res)
 }
 
 func (dc *DualCube) IsActive() bool {

glrender/dual_contour_vertexplacement.go

@@ -6,12 +6,18 @@ import (
 	"github.com/soypat/gsdf/gleval"
 )
 
-// DualContourLeastSquaresLocal is a vertex placement strategy which solves the least squares problem
-// to place vertices locally.
-type DualContourLeastSquaresLocal struct {
+type DualContourer interface {
+	// PlaceVertices should edit the FinalVertex field of all [DualCube]s in the cubes buffer.
+	// These resulting vertices are then used for quad/triangle meshing.
+	PlaceVertices(cubes []DualCube, origin ms3.Vec, res float32, sdf gleval.SDF3, posbuf []ms3.Vec, distbuf []float32, userData any) error
 }
 
-func (lsq *DualContourLeastSquaresLocal) PlaceVertices(cubes []DualCube, origin ms3.Vec, res float32, sdf gleval.SDF3, posbuf []ms3.Vec, distbuf []float32, userData any) error {
+// DualContourLeastSquares is a vertex placement strategy which solves the least squares problem
+// to place vertices.
+type DualContourLeastSquares struct {
+}
+
+func (lsq *DualContourLeastSquares) PlaceVertices(cubes []DualCube, origin ms3.Vec, res float32, sdf gleval.SDF3, posbuf []ms3.Vec, distbuf []float32, userData any) error {
 	// Prepare for normal calculation.
 	posbuf = posbuf[:0]
 	for c := range cubes {
@@ -83,7 +89,6 @@ func (lsq *DualContourLeastSquaresLocal) PlaceVertices(cubes []DualCube, origin
 		if math32.Abs(det) < 1e-5 {
 			// Singular or near-singular matrix; fall back to mean position
 			cubes[e].FinalVertex = bias
-			// dc.vert = vert
 		} else {
 			// U, S, _ := AtA.SVD()
 			// diag := S.VecDiag()
@@ -99,3 +104,10 @@ func (lsq *DualContourLeastSquaresLocal) PlaceVertices(cubes []DualCube, origin
 	}
 	return nil
 }
+
+func vertMean(verts []ms3.Vec) (mean ms3.Vec) {
+	for i := 0; i < len(verts); i++ {
+		mean = ms3.Add(mean, verts[i])
+	}
+	return ms3.Scale(1./float32(len(verts)), mean)
+}

glrender/glrender_test.go

@@ -31,7 +31,7 @@ func TestDualRender(t *testing.T) {
 	}
 	var dcr DualContourRenderer
 	var vp gleval.VecPool
-	err = dcr.Reset(sdf, res, &DualContourLeastSquaresLocal{}, &vp)
+	err = dcr.Reset(sdf, res, &DualContourLeastSquares{}, &vp)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -77,49 +77,6 @@ func TestMinecraftRender(t *testing.T) {
 	}
 }
 
-type cubeLowEdges struct {
-	active uint8 // bitfield marks active. 0:x, 1:y, 2:z
-}
-
-func contour(s gleval.SDF3, cubes []icube, origin ms3.Vec, res float32, posbuf []ms3.Vec, distbuf []float32, userData any) error {
-	iCubes := 0
-	for ; iCubes < len(cubes) && iCubes*4 < len(posbuf); iCubes++ {
-		cube := cubes[iCubes]
-		cubeCenter := cube.center(origin, res)
-		size := cube.size(res)
-
-		posbuf[iCubes*4] = cubeCenter
-		posbuf[iCubes*4+1] = ms3.Add(cubeCenter, ms3.Vec{X: size})
-		posbuf[iCubes*4+2] = ms3.Add(cubeCenter, ms3.Vec{Y: size})
-		posbuf[iCubes*4+3] = ms3.Add(cubeCenter, ms3.Vec{Z: size})
-	}
-
-	nPos := iCubes * 4
-	err := s.Evaluate(posbuf[:nPos], distbuf[:nPos], userData)
-	if err != nil {
-		return err
-	}
-
-	for j := 0; j < iCubes; j++ {
-		c := distbuf[j*4]
-		x := distbuf[j*4+1]
-		y := distbuf[j*4+2]
-		z := distbuf[j*4+3]
-		cbit := math32.Signbit(c)
-		if cbit != math32.Signbit(x) {
-
-		}
-		if cbit != math32.Signbit(y) {
-
-		}
-		if cbit != math32.Signbit(z) {
-
-		}
-	}
-
-	return nil
-}
-
 func TestSphereMarchingTriangles(t *testing.T) {
 	const r = 1.0
 	const bufsize = 1 << 12