feat(math): more math functions

johanhenriksson · Oct 18, 2024 · 3c3cb8c · 3c3cb8c
1 parent 5e7c558
commit 3c3cb8c
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Showing 5 changed files with 55 additions and 2 deletions.
diff --git a/math/math32.go b/math/math32.go
@@ -175,3 +175,46 @@ func Snap(f, multiple float32) float32 {
 func Pow(f, x float32) float32 {
 	return float32(math.Pow(float64(f), float64(x)))
 }
+
+// NextPow2 returns the next power of 2 greater than n, or n if its a power of 2.
+func NextPow2(n uint) uint {
+	n--
+	n |= n >> 1
+	n |= n >> 2
+	n |= n >> 4
+	n |= n >> 8
+	n |= n >> 16
+	n++
+	return n
+}
+
+// Ilog2 returns the uint32 value that is log2(v).
+func Ilog2(v uint32) uint32 {
+	boolToUInt32 := func(b bool) uint32 {
+		if b {
+			return 1
+		}
+		return 0
+	}
+
+	var r, shift uint32
+	r = boolToUInt32(v > 0xffff) << 4
+	v >>= r
+	shift = boolToUInt32(v > 0xff) << 3
+	v >>= shift
+	r |= shift
+	shift = boolToUInt32(v > 0xf) << 2
+	v >>= shift
+	r |= shift
+	shift = boolToUInt32(v > 0x3) << 1
+	v >>= shift
+	r |= shift
+	r |= (v >> 1)
+	return r
+}
+
+func ApproxEqual[F constraints.Float](v, v2 F) bool {
+	epsilon := F(0.0001)
+	d := v - v2
+	return d*d < epsilon*epsilon
+}
diff --git a/math/vec2/operations.go b/math/vec2/operations.go
@@ -22,6 +22,11 @@ func Distance(a, b T) float32 {
 	return a.Sub(b).Length()
 }
 
+// DistanceSqr returns the squared euclidian distance between two points.
+func DistanceSqr(a, b T) float32 {
+	return a.Sub(b).LengthSqr()
+}
+
 func Min(a, b T) T {
 	return T{
 		X: math.Min(a.X, b.X),

diff --git a/math/vec2/vec2.go b/math/vec2/vec2.go
@@ -116,7 +116,7 @@ func (v T) Div(v2 T) T {
 
 func (v T) ApproxEqual(v2 T) bool {
 	epsilon := float32(0.0001)
-	return Distance(v, v2) < epsilon
+	return DistanceSqr(v, v2) < epsilon*epsilon
 }
 
 func (v T) String() string {

diff --git a/math/vec3/operations.go b/math/vec3/operations.go
@@ -55,6 +55,11 @@ func Distance(a, b T) float32 {
 	return a.Sub(b).Length()
 }
 
+// DistanceSqr returns the squared euclidian distance between two points.
+func DistanceSqr(a, b T) float32 {
+	return a.Sub(b).LengthSqr()
+}
+
 func Mid(a, b T) T {
 	return a.Add(b).Scaled(0.5)
 }

diff --git a/math/vec3/vec3.go b/math/vec3/vec3.go
@@ -197,7 +197,7 @@ func (v T) WithZ(z float32) T {
 
 func (v T) ApproxEqual(v2 T) bool {
 	epsilon := float32(0.0001)
-	return Distance(v, v2) < epsilon
+	return DistanceSqr(v, v2) < epsilon*epsilon
 }
 
 func (v T) String() string {