polished lake generation

main.go

@@ -21,7 +21,7 @@ func main() {
 	if err != nil {
 		log.Println("Error loading settings:", err)
 		// Use default settings if loading fails
-		settings = &Settings{Detail: 1, Roughness: 0, Width: 300, Height: 300, Lakes: 0, LakeSize: 1}
+		settings = &Settings{Detail: 1, Roughness: 0, Width: 300, Height: 300, Lakes: 0, LakeSizeLower: 1, LakeSizeUpper: 5}
 	}
 
 	w.SetOnClosed(func() {
@@ -40,7 +40,7 @@ func main() {
 
 	// Initial image generation
 	noiseImg := GenerateHeightmap(settings.Width, settings.Height, int(settings.Detail))
-	canvasWithLakes, lakePixels := GenerateLakes(settings.Width, settings.Height, settings.Lakes, settings.LakeSize)
+	canvasWithLakes, lakePixels := GenerateLakes(settings.Width, settings.Height, settings.Lakes, settings.LakeSizeLower, settings.LakeSizeUpper, noiseImg)
 	darkenedHeightmap := DarkenLakeAreas(noiseImg, lakePixels)
 	compositeImg := ApplyRoughness(darkenedHeightmap, settings.Roughness)
 	heightmapImg.Image = compositeImg
@@ -70,13 +70,30 @@ func main() {
 	}
 	lakesSlider.SetValue(float64(settings.Lakes))
 
-	lakeSizeLabel := widget.NewLabel(fmt.Sprintf("Lake Size: %.0f%%", settings.LakeSize))
+	lakeSizeLowerLabel := widget.NewLabel(fmt.Sprintf("Min Lake Size: %.0f%%", settings.LakeSizeLower))
-	lakeSizeSlider := widget.NewSlider(1, 100)
+	lakeSizeLowerSlider := widget.NewSlider(1, 100)
-	lakeSizeSlider.OnChanged = func(val float64) {
+	lakeSizeUpperLabel := widget.NewLabel(fmt.Sprintf("Max Lake Size: %.0f%%", settings.LakeSizeUpper))
-		settings.LakeSize = val
+	lakeSizeUpperSlider := widget.NewSlider(1, 100)
-		lakeSizeLabel.SetText(fmt.Sprintf("Lake Size: %.0f%%", settings.LakeSize))
+
+	lakeSizeLowerSlider.OnChanged = func(val float64) {
+		settings.LakeSizeLower = val
+		if settings.LakeSizeLower > settings.LakeSizeUpper {
+			settings.LakeSizeUpper = settings.LakeSizeLower
+			lakeSizeUpperSlider.SetValue(settings.LakeSizeUpper)
 		}
-	lakeSizeSlider.SetValue(settings.LakeSize)
+		lakeSizeLowerLabel.SetText(fmt.Sprintf("Min Lake Size: %.0f%%", settings.LakeSizeLower))
+	}
+	lakeSizeLowerSlider.SetValue(settings.LakeSizeLower)
+
+	lakeSizeUpperSlider.OnChanged = func(val float64) {
+		settings.LakeSizeUpper = val
+		if settings.LakeSizeUpper < settings.LakeSizeLower {
+			settings.LakeSizeLower = settings.LakeSizeUpper
+			lakeSizeLowerSlider.SetValue(settings.LakeSizeLower)
+		}
+		lakeSizeUpperLabel.SetText(fmt.Sprintf("Max Lake Size: %.0f%%", settings.LakeSizeUpper))
+	}
+	lakeSizeUpperSlider.SetValue(settings.LakeSizeUpper)
 
 	widthEntry := widget.NewEntry()
 	widthEntry.SetText(strconv.Itoa(settings.Width))
@@ -98,7 +115,7 @@ func main() {
 
 	generateBtn := widget.NewButton("Generate", func() {
 		noiseImg := GenerateHeightmap(settings.Width, settings.Height, int(settings.Detail))
-		canvasWithLakes, lakePixels := GenerateLakes(settings.Width, settings.Height, settings.Lakes, settings.LakeSize)
+		canvasWithLakes, lakePixels := GenerateLakes(settings.Width, settings.Height, settings.Lakes, settings.LakeSizeLower, settings.LakeSizeUpper, noiseImg)
 		darkenedHeightmap := DarkenLakeAreas(noiseImg, lakePixels)
 		compositeImg := ApplyRoughness(darkenedHeightmap, settings.Roughness)
 		heightmapImg.Image = compositeImg
@@ -114,8 +131,10 @@ func main() {
 		roughnessSlider,
 		lakesLabel,
 		lakesSlider,
-		lakeSizeLabel,
+		lakeSizeLowerLabel,
-		lakeSizeSlider,
+		lakeSizeLowerSlider,
+		lakeSizeUpperLabel,
+		lakeSizeUpperSlider,
 	))
 
 	imageTab := container.NewTabItem("Image", container.NewVBox(

settings.go

@@ -12,7 +12,8 @@ type Settings struct {
 	Width         int     `json:"width"`
 	Height        int     `json:"height"`
 	Lakes         int     `json:"lakes"`
-	LakeSize  float64 `json:"lake_size"`
+	LakeSizeLower float64 `json:"lake_size_lower"`
+	LakeSizeUpper float64 `json:"lake_size_upper"`
 }
 
 func (s *Settings) Save() error {
@@ -47,7 +48,7 @@ func LoadSettings() (*Settings, error) {
 	file, err := os.Open(configFile)
 	if err != nil {
 		if os.IsNotExist(err) {
-			return &Settings{Detail: 1, Roughness: 0, Width: 300, Height: 300, Lakes: 0, LakeSize: 1}, nil
+			return &Settings{Detail: 1, Roughness: 0, Width: 300, Height: 300, Lakes: 0, LakeSizeLower: 1, LakeSizeUpper: 5}, nil
 		}
 		return nil, err
 	}

terrain.go

@@ -44,82 +44,112 @@ func (pq *priorityQueue) Pop() interface{} {
 	return item
 }
 
-// GenerateLakes creates a specific number of lakes, each covering a specific percentage of the total image area.
+// GenerateLakes creates a specific number of lakes by dividing the image into chunks and placing one lake per chunk.
-// It uses a priority-based growth algorithm to ensure each lake is a single continuous component with organic edges.
+func GenerateLakes(width, height, numLakes int, lakeSizeLower, lakeSizeUpper float64, heightmap image.Image) (image.Image, []image.Point) {
-func GenerateLakes(width, height, numLakes int, lakeSize float64) (image.Image, []image.Point) {
 	canvas := image.NewRGBA(image.Rect(0, 0, width, height))
 	draw.Draw(canvas, canvas.Bounds(), image.NewUniform(color.White), image.Point{}, draw.Src)
 
-	// Global map to track which pixels are already water to prevent duplicate darkening
+	if numLakes <= 0 || lakeSizeLower <= 0 {
-	isWater := make(map[image.Point]bool)
+		return canvas, nil
-	var allLakePixels []image.Point
-
-	if numLakes <= 0 || lakeSize <= 0 {
-		return canvas, allLakePixels
 	}
 
+	var allLakePixels []image.Point
+	randSrc := rand.New(rand.NewSource(time.Now().UnixNano()))
+
+	// 1. Divide the image into a grid
+	gridDim := int(math.Ceil(math.Sqrt(float64(numLakes))))
+	if gridDim == 0 {
+		return canvas, nil
+	}
+	chunkWidth := width / gridDim
+	chunkHeight := height / gridDim
+	if chunkWidth == 0 || chunkHeight == 0 {
+		return canvas, nil
+	}
+
+	// 2. Create a list of chunk indices and shuffle them to randomize lake placement
+	chunkIndices := make([]int, gridDim*gridDim)
+	for i := range chunkIndices {
+		chunkIndices[i] = i
+	}
+	randSrc.Shuffle(len(chunkIndices), func(i, j int) {
+		chunkIndices[i], chunkIndices[j] = chunkIndices[j], chunkIndices[i]
+	})
+
 	totalArea := float64(width * height)
-	targetPixelsPerLake := int(math.Round(totalArea * (lakeSize / 100.0)))
+	p := perlin.NewPerlin(2.0, 2.0, 1, randSrc.Int63())
+
+	// 3. Generate a lake in a subset of the chunks
+	for i := 0; i < numLakes; i++ {
+		if i >= len(chunkIndices) {
+			break
+		}
+
+		// Each lake gets a random size within the defined range
+		lakeSize := lakeSizeLower
+		if lakeSizeUpper > lakeSizeLower {
+			lakeSize = lakeSizeLower + randSrc.Float64()*(lakeSizeUpper-lakeSizeLower)
+		}
+		targetPixelsPerLake := int(math.Round(totalArea*(lakeSize/100.0))) / 2
 		if targetPixelsPerLake <= 0 {
 			targetPixelsPerLake = 1
 		}
 
-	r := rand.New(rand.NewSource(time.Now().UnixNano()))
+		chunkIndex := chunkIndices[i]
-	// One octave for maximum smoothness (no fractal detail that creates islands)
+		chunkGridX := chunkIndex % gridDim
-	p := perlin.NewPerlin(2.0, 2.0, 1, r.Int63())
+		chunkGridY := chunkIndex / gridDim
 
-	for i := 0; i < numLakes; i++ {
+		chunkRect := image.Rect(
-		// Unique seed for this specific lake
+			chunkGridX*chunkWidth,
-		seedX := r.Float64() * 10000.0
+			chunkGridY*chunkHeight,
-		seedY := r.Float64() * 10000.0
+			(chunkGridX+1)*chunkWidth,
-
+			(chunkGridY+1)*chunkHeight,
-		// Choose a random seed point
+		)
-		startPt := image.Point{X: r.Intn(width), Y: r.Intn(height)}
 
+		// Use the growth algorithm within the chunk
 		pq := &priorityQueue{}
 		heap.Init(pq)
-
-		// track pixels already considered for THIS lake
 		visited := make(map[image.Point]bool)
 
-		// Scale noise relative to expected lake size to maintain look
+		// Start near the center of the chunk
+		startPt := image.Point{
+			X: chunkRect.Min.X + chunkWidth/2,
+			Y: chunkRect.Min.Y + chunkHeight/2,
+		}
+		// just in case the center is out of bounds
+		if !startPt.In(chunkRect) {
+			continue
+		}
+
+		seedX := randSrc.Float64() * 10000.0
+		seedY := randSrc.Float64() * 10000.0
 		radius := math.Sqrt(float64(targetPixelsPerLake) / math.Pi)
-		// Much lower frequency to avoid islands and thin peninsulas
 		noiseFreq := 0.01 + (0.2 / (radius + 1.0))
 
-		// Helper to calculate score
 		getScore := func(pt image.Point) float64 {
 			dx, dy := pt.X-startPt.X, pt.Y-startPt.Y
 			dist := math.Sqrt(float64(dx*dx + dy*dy))
-
-			// Noise component
 			noise := p.Noise2D(seedX+float64(dx)*noiseFreq, seedY+float64(dy)*noiseFreq)
-
+			distPenalty := math.Pow(dist/radius, 3.0)
-			// Non-linear distance penalty: very low near center, increases rapidly at edge
+			luma, _, _, _ := heightmap.At(pt.X, pt.Y).RGBA()
-			// This makes the center much more "solid"
+			heightmapVal := float64(luma) / 65535.0
-			distPenalty := math.Pow(dist/radius, 2.0)
+			heightmapEffect := (0.5 - heightmapVal) * 1.5
-
+			return noise - distPenalty + heightmapEffect
-			return noise - distPenalty
 		}
 
-		// Push starting point
 		heap.Push(pq, &lakePixel{point: startPt, score: getScore(startPt)})
 		visited[startPt] = true
 
 		lakeCount := 0
 		for pq.Len() > 0 && lakeCount < targetPixelsPerLake {
-			// Pop the highest scoring frontier pixel
 			current := heap.Pop(pq).(*lakePixel)
 
-			// Add to canvas and global list
+			// The pixel is valid, claim it.
 			canvas.Set(current.point.X, current.point.Y, color.RGBA{R: 0, G: 0, B: 255, A: 255})
-			if !isWater[current.point] {
-				isWater[current.point] = true
 			allLakePixels = append(allLakePixels, current.point)
-			}
 			lakeCount++
 
-			// Add neighbors to frontier
+			// Add neighbors, constrained to the chunk rectangle
 			for dy := -1; dy <= 1; dy++ {
 				for dx := -1; dx <= 1; dx++ {
 					if dx == 0 && dy == 0 {
@@ -127,12 +157,10 @@ func GenerateLakes(width, height, numLakes int, lakeSize float64) (image.Image,
 					}
 					neighbor := image.Point{X: current.point.X + dx, Y: current.point.Y + dy}
 
-					// Bounds check
+					if !neighbor.In(chunkRect) || visited[neighbor] {
-					if neighbor.X < 0 || neighbor.X >= width || neighbor.Y < 0 || neighbor.Y >= height {
 						continue
 					}
 
-					if !visited[neighbor] {
 					visited[neighbor] = true
 					heap.Push(pq, &lakePixel{
 						point: neighbor,
@@ -142,7 +170,6 @@ func GenerateLakes(width, height, numLakes int, lakeSize float64) (image.Image,
 			}
 		}
 	}
-	}
 
 	return canvas, allLakePixels
 }
@@ -153,14 +180,24 @@ func DarkenLakeAreas(heightmap image.Image, lakePixels []image.Point) image.Imag
 	composite := image.NewRGBA(bounds)
 	draw.Draw(composite, bounds, heightmap, image.Point{}, draw.Src)
 
+	// Create a map for quick lookup of lake pixels
+	isLake := make(map[image.Point]bool)
 	for _, p := range lakePixels {
-		c := composite.At(p.X, p.Y)
+		isLake[p] = true
+	}
+
+	for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
+		for x := bounds.Min.X; x < bounds.Max.X; x++ {
+			if !isLake[image.Point{X: x, Y: y}] {
+				c := composite.At(x, y)
 				r, g, b, a := c.RGBA()
 				// Darken by 15%
 				r = uint32(float64(r) * 0.85)
 				g = uint32(float64(g) * 0.85)
 				b = uint32(float64(b) * 0.85)
-		composite.Set(p.X, p.Y, color.RGBA64{R: uint16(r), G: uint16(g), B: uint16(b), A: uint16(a)})
+				composite.Set(x, y, color.RGBA64{R: uint16(r), G: uint16(g), B: uint16(b), A: uint16(a)})
+			}
+		}
 	}
 
 	return composite