Merge branch 'main' of github.com:make-42/xyosc

fastsqrt/fastsqrt.go

@@ -0,0 +1,27 @@
+package fastsqrt
+
+import "math"
+
+const magic32 = 0x5F375A86
+
+func FastInvSqrt32(n float32) float32 {
+	// If n is negative return NaN
+	if n < 0 {
+		return float32(math.NaN())
+	} // n2 and th are for one iteration of Newton's method later
+	n2, th := n*0.5, float32(1.5) // Use math.Float32bits to represent the float32, n, as
+	// an uint32 without modification.
+	b := math.Float32bits(n) // Use the new uint32 view of the float32 to shift the bits
+	// of the float32 1 to the right, chopping off 1 bit from
+	// the fraction part of the float32.
+	b = magic32 - (b >> 1) // Use math.Float32frombits to convert the uint32 bits back
+	// into their float32 representation, again no actual change
+	// in the bits, just a change in how we treat them in memory.
+	// f is now our answer of 1 / sqrt(n)
+	f := math.Float32frombits(b) // Perform one iteration of Newton's method on f to improve
+	// accuracy
+	f *= th - (n2 * f * f)
+
+	// And return our fast inverse square root result
+	return f
+}

main.go

@@ -44,6 +44,8 @@ func main() {
 			fAY := -float32(AY) * config.Config.Gain * float32(scale)
 			fBX := float32(BX) * config.Config.Gain * float32(scale)
 			fBY := -float32(BY) * config.Config.Gain * float32(scale)
+			//inv := fastsqrt.FastInvSqrt32((fBX-fAX)*(fBX-fAX) + (fBY-fBY)*(fBY-fBY))
+			//colorAdjusted := color.RGBA{config.AccentColor.R, config.AccentColor.G, config.AccentColor.B, uint8(255 * inv * config.Config.LineOpacity)}
 			rl.DrawLineEx(rl.NewVector2(float32(config.Config.WindowWidth/2)+fAX, float32(config.Config.WindowWidth/2)+fAY), rl.NewVector2(float32(config.Config.WindowWidth/2)+fBX, float32(config.Config.WindowWidth/2)+fBY), config.Config.LineThickness, config.AccentColor)
 			AX = BX
 			AY = BY