feat: Custom noise type - enable user defined function

Author: KEINOS

.github/go-mod-tidy.sh

@@ -27,6 +27,7 @@ go get "github.com/aquilax/go-perlin"
 go get "github.com/ojrac/opensimplex-go"
 go get "github.com/pkg/errors"
 go get "github.com/stretchr/testify"
+go get "gonum.org/v1/plot/..."
 
 echo '* Run go tidy ...'
 go mod tidy

README.md

@@ -17,8 +17,10 @@ In the example below, 1 dimmentional method `noise.Generator.Eval64(x)` was used
 // const seed = 100       // noise pattern ID
 // const smoothness = 100 // noise smoothness
 //
+// // noiseType choises
 // noiseType := noise.Perlin
 // noiseType := noise.OpenSimplex
+// noiseType := noise.Custom
 n, err := noise.New(noiseType, seed)
 
 yy := n.Eval64(x / smoothness) // yy is between -1.0 and 1.0 of float64
@@ -27,6 +29,7 @@ y := (yy + 1) / 2 * 500        // y is between 0 and 500
 
 ![](./_example/2d/2d_perlin.png)
 ![](./_example/2d/2d_opensimplex.png)
+![](./_example/2d/2d_pseudorandom.png)
 
 - [Source](./_example/2d)
 
@@ -84,6 +87,10 @@ go get "github.com/KEINOS/go-noise"
 
 ### Constructor
 
+```go
+noise.New(noiseType noise.Algo, seed int64) (noise.Generator, error)
+```
+
 ```go
 import "github.com/KEINOS/go-noise"
 

_example/2d/2d_pseudorandom.png

@@ -2,6 +2,7 @@ package main
 
 import (
 	"log"
+	"math/rand"
 
 	"github.com/KEINOS/go-noise"
 	"gonum.org/v1/plot"
@@ -25,6 +26,13 @@ const (
 	smoothness = 100
 )
 
+// rnd is the rand.Rand used by PseudoRrandom() which is the Custom noise generator.
+var rnd *rand.Rand
+
+// ----------------------------------------------------------------------------
+//  Main
+// ----------------------------------------------------------------------------
+
 func main() {
 	{
 		// Create Perlin noise generator with seed 100.
@@ -53,11 +61,34 @@ func main() {
 			log.Fatal(err)
 		}
 	}
+
+	{
+		// Create user-defined Pseudorandom noise generator with seed 100.
+		gen, err := noise.New(noise.Custom, seed)
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		// Set user-defined noise function.
+		if err := gen.SetEval64(PseudoRrandom); err != nil {
+			log.Fatal(err)
+		}
+
+		pathFile := "./2d_pseudorandom.png"
+
+		if err := GenGraphImage(gen, "User Custom Noise (Pseudo Random)", pathFile); err != nil {
+			log.Fatal(err)
+		}
+	}
 }
 
+// ----------------------------------------------------------------------------
+//  Functions
+// ----------------------------------------------------------------------------
+
 // GenGraphImage generates a graph image with the specified generator and saves
 // it to the specified path.
-func GenGraphImage(gen noise.Noise, title string, pathFile string) error {
+func GenGraphImage(gen noise.Generator, title string, pathFile string) error {
 	// Create plotter.
 	pltr := GenPlotter(title)
 
@@ -103,3 +134,25 @@ func GenPlotter(titile string) *plot.Plot {
 func Normalize(v float64) float64 {
 	return (v + 1) / 2 * float64(height)
 }
+
+// PseudoRrandom is a pseudo-random noise function for use as a user-defined
+// noise generator for the Eval64 method.
+func PseudoRrandom(seed int64, dim ...float64) float64 {
+	if rnd == nil {
+		// Set the seed.
+		rnd = rand.New(rand.NewSource(seed))
+	}
+
+	for i := 0; i < len(dim); i++ {
+		v := int(dim[i])
+
+		for ii := 0; ii < v; ii++ {
+			//nolint:gosec // Use of weak random number generation is intended for simple examples.
+			_ = rnd.Float64()
+		}
+	}
+
+	s := rnd.Float64() // 0.0 - 0.9999...
+
+	return s*2 - 1 // Convert [0.0,1.0) to [-1.0,1.0]
+}

_example/2d/main.go

@@ -10,7 +10,20 @@ require (
 )
 
 require (
+	gioui.org v0.0.0-20210308172011-57750fc8a0a6 // indirect
+	git.sr.ht/~sbinet/gg v0.3.1 // indirect
+	github.com/ajstarks/svgo v0.0.0-20211024235047-1546f124cd8b // indirect
 	github.com/davecgh/go-spew v1.1.0 // indirect
+	github.com/go-fonts/liberation v0.2.0 // indirect
+	github.com/go-latex/latex v0.0.0-20210823091927-c0d11ff05a81 // indirect
+	github.com/go-pdf/fpdf v0.6.0 // indirect
+	github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
+	golang.org/x/exp v0.0.0-20191002040644-a1355ae1e2c3 // indirect
+	golang.org/x/image v0.0.0-20220302094943-723b81ca9867 // indirect
+	golang.org/x/sys v0.0.0-20210304124612-50617c2ba197 // indirect
+	golang.org/x/text v0.3.7 // indirect
+	gonum.org/v1/plot v0.11.0 // indirect
 	gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c // indirect
+	rsc.io/pdf v0.1.1 // indirect
 )

go.mod

@@ -1,17 +1,105 @@
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+gonum.org/v1/plot v0.11.0 h1:z2ZkgNqW34d0oYUzd80RRlc0L9kWtenqK4kflZG1lGc=
+gonum.org/v1/plot v0.11.0/go.mod h1:fH9YnKnDKax0u5EzHVXvhN5HJwtMFWIOLNuhgUahbCQ=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
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 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+honnef.co/go/tools v0.1.3/go.mod h1:NgwopIslSNH47DimFoV78dnkksY2EFtX0ajyb3K/las=
+rsc.io/pdf v0.1.1 h1:k1MczvYDUvJBe93bYd7wrZLLUEcLZAuF824/I4e5Xr4=
+rsc.io/pdf v0.1.1/go.mod h1:n8OzWcQ6Sp37PL01nO98y4iUCRdTGarVfzxY20ICaU4=

go.sum

@@ -1,6 +1,7 @@
 package noise
 
 import (
+	"github.com/KEINOS/go-noise/pkg/custom"
 	"github.com/KEINOS/go-noise/pkg/opensimplex"
 	"github.com/KEINOS/go-noise/pkg/perlin"
 	"github.com/pkg/errors"
@@ -16,6 +17,8 @@ const (
 	Perlin
 	// OpenSimplex noise type.
 	OpenSimplex
+	// Custom uses the user-defined function to generate noise.
+	Custom
 )
 
 // ----------------------------------------------------------------------------
@@ -46,6 +49,8 @@ type Generator interface {
 	// Implementations of this method must return the same value if the seed
 	// value is the same.
 	Eval64(dim ...float64) float64
+	SetEval32(f func(seed int64, dim ...float32) float32) error
+	SetEval64(f func(seed int64, dim ...float64) float64) error
 }
 
 // ----------------------------------------------------------------------------
@@ -59,6 +64,8 @@ func New(noiseType Algo, seed int64) (Generator, error) {
 		return perlin.New(seed), nil
 	case OpenSimplex:
 		return opensimplex.New(seed), nil
+	case Custom:
+		return custom.New(seed), nil
 	}
 
 	return nil, errors.New("unknown noise type")

noise.go

@@ -0,0 +1,76 @@
+/*
+Package custom provides a noise generator using the user-defined function.
+Which implements github.com/KEINOS/go-noise/noise interface.
+
+You need to define the function before calling `Eval32` or `Eval64`.
+*/
+package custom
+
+import (
+	"math/rand"
+	"time"
+
+	"github.com/pkg/errors"
+)
+
+// Generator holds parameters of user-defined noise generator.
+type Generator struct {
+	// func32 is the user-defined function for float32.
+	func32 func(seed int64, dim ...float32) float32
+	// func64 is the user-defined function for float64.
+	func64 func(seed int64, dim ...float64) float64
+	// Seed holds the seed value for the noise.
+	Seed int64
+}
+
+// New returns a seeded Perlin noise instance.
+func New(seed int64) *Generator {
+	// Rand that uses random values from src to generate other random values.
+	return &Generator{
+		Seed: seed,
+	}
+}
+
+// Eval32 returns a float32 noise value using the user-defined function for the given coordinates.
+func (n *Generator) Eval32(dim ...float32) float32 {
+	return n.func32(n.Seed, dim...)
+}
+
+// Eval64 returns a float64 noise value using the user-defined function for the given coordinates.
+func (n *Generator) Eval64(dim ...float64) float64 {
+	return n.func64(n.Seed, dim...)
+}
+
+// SetEval32 sets the user-defined noise generator function for float32.
+func (n *Generator) SetEval32(f func(seed int64, dim ...float32) float32) error {
+	// Check the function.
+	rand.Seed(time.Now().UnixNano())
+
+	//nolint:gosec // Use of weak random number generation is intended here.
+	dummyInput := rand.Float32()
+
+	if v := f(n.Seed, dummyInput, dummyInput); v <= -1 || 1 < v {
+		return errors.New("the function must return a value between -1 and 1")
+	}
+
+	n.func32 = f
+
+	return nil
+}
+
+// SetEval64 sets the user-defined noise generator function for float64.
+func (n *Generator) SetEval64(f func(seed int64, dim ...float64) float64) error {
+	// Check the function.
+	rand.Seed(time.Now().UnixNano())
+
+	//nolint:gosec // Use of weak random number generation is intended here.
+	dummyInput := rand.Float64()
+
+	if v := f(n.Seed, dummyInput, dummyInput); v <= -1 || 1 < v {
+		return errors.New("the function must return a value between -1 and 1")
+	}
+
+	n.func64 = f
+
+	return nil
+}