initial commit, with support for basic lake generation.

heightmap.go

@@ -0,0 +1,56 @@
+package main
+
+import (
+	"image"
+	"image/color"
+	"image/draw"
+	"math/rand"
+	"time"
+
+	"github.com/aquilax/go-perlin"
+)
+
+const (
+	alpha = 2.
+	beta  = 2.
+	n     = 3
+)
+
+func GenerateHeightmap(width, height, octaves int) image.Image {
+	p := perlin.NewPerlin(alpha, beta, n, rand.New(rand.NewSource(time.Now().UnixNano())).Int63())
+	img := image.NewGray(image.Rect(0, 0, width, height))
+
+	for x := 0; x < width; x++ {
+		for y := 0; y < height; y++ {
+			var noise float64
+			frequency := 1.0
+			amplitude := 1.0
+			maxAmplitude := 0.0
+
+			for i := 0; i < octaves; i++ {
+				noise += p.Noise2D(float64(x)*frequency/100, float64(y)*frequency/100) * amplitude
+				maxAmplitude += amplitude
+				amplitude /= 2.0
+				frequency *= 2.0
+			}
+
+			noise /= maxAmplitude
+			grayColor := uint8((noise + 1) * 127.5)
+			img.SetGray(x, y, color.Gray{Y: grayColor})
+		}
+	}
+
+	return img
+}
+
+func ApplyRoughness(heightmap image.Image, roughness float64) image.Image {
+	bounds := heightmap.Bounds()
+	composite := image.NewRGBA(bounds)
+	draw.Draw(composite, bounds, heightmap, image.Point{}, draw.Src)
+
+	alphaValue := 255 - uint8(roughness*2.55)
+	overlay := image.NewUniform(color.RGBA{R: 128, G: 128, B: 128, A: alphaValue})
+	draw.Draw(composite, bounds, overlay, image.Point{}, draw.Over)
+
+	return composite
+}