Merge Dev (#6)

* fix CPU ellipse; fix GPU vec2 ssbo; add polyssbo/translatemulti2d; 87% test coverage;

* add gsdf.Builder to font config

* update README

* fix uninitialized Font crash; fix polygon self-closing case; admit multiple identical SSBOs; color conversion additions

Author: soypat

README.md

@@ -11,15 +11,19 @@ for visualization or 3D printing file outputs. Quick jump to usage: [bolt exampl
 
 All images and shapes in readme were generated using this library.
 
-![circle](https://github.com/user-attachments/assets/91c99f47-0c52-4cb1-83e7-452b03b69dff)
 ![bolt-example](https://github.com/user-attachments/assets/8da50871-2415-423f-beb3-0d78ad67c79e)
+![circle](https://github.com/user-attachments/assets/91c99f47-0c52-4cb1-83e7-452b03b69dff)
+![text](https://github.com/user-attachments/assets/73a90941-9279-449d-9f4d-3f2746af5dd5)
 
 ## Requirements
+
 - [Go](https://go.dev/)
 - **Optional**: See latest requirements on [go-glfw](https://github.com/go-gl/glfw) if using GPU
 
 ## Features
 
+- High test coverage (when GPU available, not the case in CI)
+
 - Extremely coherent API design.
 
 - UI for visualizing parts, rendered directly from shaders. See [UI example](./examples/ui-mandala) by running `go run ./examples/ui-mandala`
@@ -128,4 +132,4 @@ go run ./examples/fibonacci-showerhead -resdiv 350  36,16s user 0,76s system 100
 
 ![iso-screw](https://github.com/user-attachments/assets/6bc987b9-d522-42a4-89df-71a20c3ae7ff)
 ![array-triangles](https://github.com/user-attachments/assets/6a479889-2836-464c-b8ea-82109a5aad13)
-![geb-book-cover](https://github.com/user-attachments/assets/1ed945fb-5729-4028-bed8-26e0de3073ab)
+![geb-book-cover](https://github.com/user-attachments/assets/a6727481-07f3-4636-8e1c-9b1a02bb108f)

cpu_evaluators.go

@@ -1,13 +1,22 @@
 package gsdf
 
 import (
+	"math"
+
 	"github.com/chewxy/math32"
 	"github.com/soypat/glgl/math/ms1"
 	"github.com/soypat/glgl/math/ms2"
 	"github.com/soypat/glgl/math/ms3"
 	"github.com/soypat/gsdf/gleval"
 )
 
+// minReduce takes element-wise minimum of arguments and stores to first argument.
+func minReduce(d1AndDst, d2 []float32) {
+	for i := range d1AndDst {
+		d1AndDst[i] = math32.Min(d1AndDst[i], d2[i])
+	}
+}
+
 func (u *sphere) Evaluate(pos []ms3.Vec, dist []float32, userData any) error {
 	r := u.r
 	for i, p := range pos {
@@ -129,9 +138,7 @@ func (u *OpUnion) Evaluate(pos []ms3.Vec, dist []float32, userData any) error {
 		if err != nil {
 			return err
 		}
-		for i, d := range dist {
-			dist[i] = math32.Min(d, auxDist[i])
-		}
+		minReduce(dist, auxDist)
 	}
 	return nil
 }
@@ -619,8 +626,8 @@ func (c *hex2D) Evaluate(pos []ms2.Vec, dist []float32, userData any) error {
 
 func (c *ellipse2D) Evaluate(pos []ms2.Vec, dist []float32, userData any) error {
 	// https://iquilezles.org/articles/ellipsedist
-	a, b := c.a, c.b
 	for i, p := range pos {
+		a, b := c.a, c.b
 		p = ms2.AbsElem(p)
 		if p.X > p.Y {
 			p.X, p.Y = p.Y, p.X
@@ -646,8 +653,8 @@ func (c *ellipse2D) Evaluate(pos []ms2.Vec, dist []float32, userData any) error
 			co = (ry + signf(l)*rx + math32.Abs(g)/(rx*ry) - m) / 2
 		} else {
 			h := 2 * m * n * math32.Sqrt(d)
-			s := signf(q+h) * math32.Pow(math32.Abs(q+h), 1./3.)
-			u := signf(q-h) * math32.Pow(math32.Abs(q-h), 1./3.)
+			s := signf(q+h) * math32.Cbrt(math32.Abs(q+h))
+			u := signf(q-h) * math32.Cbrt(math32.Abs(q-h))
 
 			rx := -s - u - 4*c + 2*m2
 			ry := sqrt3 * (s - u)
@@ -927,7 +934,6 @@ func (c *circarray) Evaluate(pos []ms3.Vec, dist []float32, userData any) error
 	ncirc := float32(c.circleDiv)
 	ninsm1 := float32(c.nInst - 1)
 	for i, p := range pos {
-
 		pangle := math32.Atan2(p.Y, p.X)
 		id := math32.Floor(pangle / angle)
 		if id < 0 {
@@ -958,9 +964,7 @@ func (c *circarray) Evaluate(pos []ms3.Vec, dist []float32, userData any) error
 	if err != nil {
 		return err
 	}
-	for i, d := range dist {
-		dist[i] = math32.Min(d, dist1[i])
-	}
+	minReduce(dist, dist1)
 	return nil
 }
 
@@ -1031,3 +1035,46 @@ func (l *lines2D) Evaluate(pos []ms2.Vec, dist []float32, userData any) error {
 	}
 	return nil
 }
+
+func (c *translateMulti2D) Evaluate(pos []ms2.Vec, dist []float32, userData any) error {
+	vp, err := gleval.GetVecPool(userData)
+	if err != nil {
+		return err
+	}
+	for i := range dist {
+		dist[i] = math.MaxFloat32
+	}
+	d1 := vp.Float.Acquire(len(pos))
+	defer vp.Float.Release(d1)
+	for _, p := range c.displacements {
+		t2d := translate2D{
+			s: c.s,
+			p: p,
+		}
+		err = t2d.Evaluate(pos, d1, userData)
+		if err != nil {
+			return err
+		}
+		minReduce(dist, d1)
+	}
+	return nil
+}
+
+func (c *rotation2D) Evaluate(pos []ms2.Vec, dist []float32, userData any) error {
+	sdf, err := gleval.AssertSDF2(c.s)
+	if err != nil {
+		return err
+	}
+	vp, err := gleval.GetVecPool(userData)
+	if err != nil {
+		return err
+	}
+	posTransf := vp.V2.Acquire(len(pos))
+	defer vp.V2.Release(posTransf)
+	invT := c.tInv
+	for i, p := range pos {
+		posTransf[i] = ms2.MulMatVec(invT, p)
+	}
+	err = sdf.Evaluate(posTransf, dist, userData)
+	return err
+}

examples/image-text/text.go

@@ -8,8 +8,6 @@ import (
 	"runtime"
 	"time"
 
-	"github.com/chewxy/math32"
-	"github.com/soypat/glgl/math/ms1"
 	"github.com/soypat/gsdf"
 	"github.com/soypat/gsdf/forge/textsdf"
 	"github.com/soypat/gsdf/glbuild"
@@ -66,32 +64,12 @@ func main() {
 
 	charHeight := sdf2.Bounds().Size().Y
 	edgeAliasing := charHeight / 1000
+	conversion := gsdfaux.ColorConversionLinearGradient(edgeAliasing, color.Black, color.White)
 	start := time.Now()
-	err = gsdfaux.RenderPNGFile(filename, sdf2, 300, blackAndWhite(edgeAliasing))
+	err = gsdfaux.RenderPNGFile(filename, sdf2, 300, conversion)
 	if err != nil {
 		log.Fatal(err)
 	}
+	_ = conversion
 	fmt.Println("PNG file rendered to", filename, "in", time.Since(start))
 }
-
-func blackAndWhite(edgeSmooth float32) func(d float32) color.Color {
-	if edgeSmooth <= 0 {
-		return blackAndWhiteNoSmoothing
-	}
-	return func(d float32) color.Color {
-		// Smoothstep anti-aliasing near the edge
-		blend := 0.5 + 0.5*math32.Tanh(d/edgeSmooth)
-		// Clamp blend to [0, 1] for valid grayscale values
-		blend = ms1.Clamp(blend, 0, 1)
-		// Convert blend to grayscale
-		grayValue := uint8(blend * 255)
-		return color.Gray{Y: grayValue}
-	}
-}
-
-func blackAndWhiteNoSmoothing(d float32) color.Color {
-	if d < 0 {
-		return color.Black
-	}
-	return color.White
-}

examples/ui-geb/uigeb.go

@@ -24,6 +24,7 @@ func scene(bld *gsdf.Builder) (glbuild.Shader3D, error) {
 	var f textsdf.Font
 	f.Configure(textsdf.FontConfig{
 		RelativeGlyphTolerance: 0.01,
+		Builder:                bld,
 	})
 	err := f.LoadTTFBytes(textsdf.ISO3098TTF())
 	if err != nil {
@@ -57,7 +58,7 @@ func scene(bld *gsdf.Builder) (glbuild.Shader3D, error) {
 	sclG := ms2.DivElem(sz, szG)
 	sclE := ms2.DivElem(sz, szE)
 	sclB := ms2.DivElem(sz, szB)
-	fmt.Println(sclG, sclE, sclB)
+
 	// Create 3D letters.
 	L := sz.Max()
 	G3 := bld.Extrude(G, L)
@@ -89,6 +90,7 @@ func scene(bld *gsdf.Builder) (glbuild.Shader3D, error) {
 
 func main() {
 	var bld gsdf.Builder
+	// bld.SetFlags(gsdf.FlagUseShaderBuffers)
 	shape, err := scene(&bld)
 	shape = bld.Scale(shape, 0.3)
 	if err != nil {

forge/textsdf/font.go

@@ -16,9 +16,12 @@ import (
 const firstBasic = '!'
 const lastBasic = '~'
 
+var defaultBuilder = &gsdf.Builder{}
+
 type FontConfig struct {
 	// RelativeGlyphTolerance sets the permissible curve tolerance for glyphs. Must be between 0..1. If zero a reasonable value is chosen.
 	RelativeGlyphTolerance float32
+	Builder                *gsdf.Builder
 }
 
 // Font implements font parsing and glyph (character) generation.
@@ -28,8 +31,8 @@ type Font struct {
 	// basicGlyphs optimized array access for common ASCII glyphs.
 	basicGlyphs [lastBasic - firstBasic + 1]glyph
 	// Other kinds of glyphs.
-	otherGlyphs map[rune]glyph
-	bld         gsdf.Builder
+	otherGlyphs map[rune]*glyph
+	bld         *gsdf.Builder
 	reltol      float32 // Set by config or reset call if zeroed.
 }
 
@@ -39,6 +42,9 @@ func (f *Font) Configure(cfg FontConfig) error {
 	}
 	f.reset()
 	f.reltol = cfg.RelativeGlyphTolerance
+	if cfg.Builder != nil {
+		f.bld = cfg.Builder
+	}
 	return nil
 }
 
@@ -59,7 +65,7 @@ func (f *Font) reset() {
 		f.basicGlyphs[i] = glyph{}
 	}
 	if f.otherGlyphs == nil {
-		f.otherGlyphs = make(map[rune]glyph)
+		f.otherGlyphs = make(map[rune]*glyph)
 	} else {
 		for k := range f.otherGlyphs {
 			delete(f.otherGlyphs, k)
@@ -68,6 +74,9 @@ func (f *Font) reset() {
 	if f.reltol == 0 {
 		f.reltol = 0.15
 	}
+	if f.bld == nil {
+		f.bld = defaultBuilder
+	}
 }
 
 type glyph struct {
@@ -133,30 +142,38 @@ func (f *Font) AdvanceWidth(c rune) float32 {
 
 // Glyph returns a SDF for a character defined by the argument rune.
 func (f *Font) Glyph(c rune) (_ glbuild.Shader2D, err error) {
-	var g glyph
+	g, err := f.glyph(c)
+	if err != nil {
+		return nil, err
+	}
+	return g.sdf, nil
+}
+
+func (f *Font) glyph(c rune) (g *glyph, err error) {
 	if c >= firstBasic && c <= lastBasic {
 		// Basic ASCII glyph case.
-		g = f.basicGlyphs[c-firstBasic]
+		g = &f.basicGlyphs[c-firstBasic]
 		if g.sdf == nil {
 			// Glyph not yet created. create it.
-			g, err = f.makeGlyph(c)
+			gc, err := f.makeGlyph(c)
 			if err != nil {
 				return nil, err
 			}
-			f.basicGlyphs[c-firstBasic] = g
+			*g = gc
 		}
-		return g.sdf, nil
+		return g, nil
 	}
 	// Unicode or other glyph.
 	g, ok := f.otherGlyphs[c]
 	if !ok {
-		g, err = f.makeGlyph(c)
+		gc, err := f.makeGlyph(c)
 		if err != nil {
 			return nil, err
 		}
+		g = &gc
 		f.otherGlyphs[c] = g
 	}
-	return g.sdf, nil
+	return g, nil
 }
 
 func (f *Font) scale() fixed.Int26_6 {
@@ -180,7 +197,7 @@ func (f *Font) scaleout() float32 {
 
 func (f *Font) makeGlyph(char rune) (glyph, error) {
 	g := &f.gb
-	bld := &f.bld
+	bld := f.bld
 
 	idx := f.ttf.Index(char)
 	scale := f.scale()
@@ -219,8 +236,8 @@ func (f *Font) makeGlyph(char rune) (glyph, error) {
 
 func glyphCurve(bld *gsdf.Builder, points []truetype.Point, start, end int, tol, scale float32) (glbuild.Shader2D, bool, error) {
 	var (
-		sampler = ms2.Spline3Sampler{Spline: quadBezier, Tolerance: tol}
-		sum     float32
+		sampler    = ms2.Spline3Sampler{Spline: quadBezier, Tolerance: tol}
+		windingSum float32
 	)
 	points = points[start:end]
 	n := len(points)
@@ -241,7 +258,7 @@ func glyphCurve(bld *gsdf.Builder, points []truetype.Point, start, end int, tol,
 			// on-on Straight line.
 			poly = append(poly, v0)
 			i += 1
-			sum += (v0.X - vPrev.X) * (v0.Y + vPrev.Y)
+			windingSum += (v0.X - vPrev.X) * (v0.Y + vPrev.Y)
 			vPrev = v0
 			continue
 
@@ -269,10 +286,10 @@ func glyphCurve(bld *gsdf.Builder, points []truetype.Point, start, end int, tol,
 		}
 		poly = append(poly, v0) // Append start point.
 		poly = sampler.SampleBisect(poly, 4)
-		sum += (v0.X - vPrev.X) * (v0.Y + vPrev.Y)
+		windingSum += (v0.X - vPrev.X) * (v0.Y + vPrev.Y)
 		vPrev = v0
 	}
-	return bld.NewPolygon(poly), sum > 0, bld.Err()
+	return bld.NewPolygon(poly), windingSum > 0, bld.Err()
 }
 
 func p2v(p truetype.Point, scale float32) ms2.Vec {
@@ -282,12 +299,7 @@ func p2v(p truetype.Point, scale float32) ms2.Vec {
 	}
 }
 
-var quadBezier = ms2.NewSpline3([]float32{
-	1, 0, 0, 0,
-	-2, 2, 0, 0,
-	1, -2, 1, 0,
-	0, 0, 0, 0,
-})
+var quadBezier = ms2.SplineBezierQuadratic()
 
 func onbits3(points []truetype.Point, start, end, i int) uint32 {
 	n := end - start