fix eq triangle calculation

cpu_evaluators.go

@@ -94,16 +94,6 @@ func (h *hex) Evaluate(pos []ms3.Vec, dist []float32, userData any) error {
 	return nil
 }
 
-func (t *tri) Evaluate(pos []ms3.Vec, dist []float32, userData any) error {
-	h1, h2 := t.args()
-	for i, p := range pos {
-		q := ms3.AbsElem(p)
-		m1 := maxf(q.X*tribisect+p.Y*0.5, -p.Y)
-		dist[i] = maxf(q.Z-h2, m1-h1)
-	}
-	return nil
-}
-
 func evaluateSDF3(obj bounder3, pos []ms3.Vec, dist []float32, userData any) error {
 	sdf, err := gleval.AssertSDF3(obj)
 	if err != nil {
@@ -520,7 +510,7 @@ func (e *extrusion) Evaluate(pos []ms3.Vec, dist []float32, userData any) error
 	if err != nil {
 		return err
 	}
-	h := e.h
+	h := e.h / 2
 	for i, p := range pos {
 		d := dist[i]
 		wy := math32.Abs(p.Z) - h
@@ -557,7 +547,7 @@ func (c *circle2D) Evaluate(pos []ms2.Vec, dist []float32, userData any) error {
 
 func (t *equilateralTri2d) Evaluate(pos []ms2.Vec, dist []float32, userData any) error {
 	const k = sqrt3
-	r := t.hTri * tribisect
+	r := t.hTri / sqrt3
 	for i, p := range pos {
 		p.X = math32.Abs(p.X) - r
 		p.Y += r / k

gsdf2d.go

@@ -73,7 +73,7 @@ func (t *equilateralTri2d) AppendShaderName(b []byte) []byte {
 }
 
 func (t *equilateralTri2d) AppendShaderBody(b []byte) []byte {
-	b = appendFloatDecl(b, "h", t.hTri/1.7)
+	b = appendFloatDecl(b, "h", t.hTri/sqrt3)
 	b = append(b, `const float k = sqrt(3.0);
     p.x = abs(p.x) - h;
     p.y = p.y + h/k;
@@ -332,7 +332,7 @@ func (e *extrusion) AppendShaderName(b []byte) []byte {
 }
 
 func (e *extrusion) AppendShaderBody(b []byte) []byte {
-	b = appendFloatDecl(b, "h", e.h)
+	b = appendFloatDecl(b, "h", e.h/2)
 	b = appendDistanceDecl(b, e.s, "d", "p.xy")
 	b = append(b, `vec2 w = vec2( d, abs(p.z) - h );
 return min(max(w.x,w.y),0.0) + length(max(w,0.0));`...)