reworked road generation with focus on main roads, secondary streets and smaller arterial roads

buildings.go

@@ -173,22 +173,68 @@ func GenerateBuildings(
 	searchTries := 100                                // Number of attempts to find a spot for a building around an anchor
 	maxPlacementAttempts := settings.NumBuildings * 5 // To prevent infinite loops
 	minBuildingSizePx, maxBuildingSizePx := getBuildingSizeRangePixels(settings, width, height)
+	anchorUsage := make(map[image.Point]int, len(anchorPoints))
+	normalAnchorCap := 0
+	exitAnchorCap := 0
+	if len(normalRoadAnchors) > 0 {
+		normalAnchorCap = max(2, int(math.Ceil((float64(settings.NumBuildings)/float64(len(normalRoadAnchors)))*1.15)))
+	}
+	if len(exitRoadAnchors) > 0 {
+		exitAnchorCap = max(1, int(math.Ceil((float64(settings.NumBuildings)/float64(len(exitRoadAnchors)))*0.20)))
+	}
+
+	pickAnchorWithCapacity := func(candidates []image.Point, capLimit int) (image.Point, bool) {
+		if len(candidates) == 0 {
+			return image.Point{}, false
+		}
+		if capLimit <= 0 {
+			return candidates[randSrc.Intn(len(candidates))], true
+		}
+		best := candidates[randSrc.Intn(len(candidates))]
+		bestCount := anchorUsage[best]
+		for tries := 0; tries < min(16, len(candidates)*2); tries++ {
+			candidate := candidates[randSrc.Intn(len(candidates))]
+			count := anchorUsage[candidate]
+			if count < capLimit {
+				return candidate, true
+			}
+			if count < bestCount {
+				best = candidate
+				bestCount = count
+			}
+		}
+		if bestCount < capLimit {
+			return best, true
+		}
+		return image.Point{}, false
+	}
 
 	for buildingsPlaced < settings.NumBuildings && maxPlacementAttempts > 0 {
 		maxPlacementAttempts--
 
 		// Select an anchor point for the new building
 		var anchor image.Point
+		usedRoadAnchor := false
 		if randSrc.Float64() > settings.BuildingDistribution/100.0 {
 			// Buildings should only rarely use exit-road anchors.
 			useExitAnchor := len(exitRoadAnchors) > 0 && randSrc.Float64() < 0.02
 			if useExitAnchor {
-				anchor = exitRoadAnchors[randSrc.Intn(len(exitRoadAnchors))]
+				if a, ok := pickAnchorWithCapacity(exitRoadAnchors, exitAnchorCap); ok {
+					anchor = a
+					usedRoadAnchor = true
+				}
 			} else if len(normalRoadAnchors) > 0 {
-				anchor = normalRoadAnchors[randSrc.Intn(len(normalRoadAnchors))]
+				if a, ok := pickAnchorWithCapacity(normalRoadAnchors, normalAnchorCap); ok {
+					anchor = a
+					usedRoadAnchor = true
+				}
 			} else if len(anchorPoints) > 0 {
-				anchor = anchorPoints[randSrc.Intn(len(anchorPoints))]
-			} else {
+				if a, ok := pickAnchorWithCapacity(anchorPoints, normalAnchorCap); ok {
+					anchor = a
+					usedRoadAnchor = true
+				}
+			}
+			if !usedRoadAnchor {
 				p, ok := sampleRandomLandPoint(width, height, waterMask, roadMask, randSrc)
 				if !ok {
 					continue
@@ -247,6 +293,9 @@ func GenerateBuildings(
 					img.Set(p.X, p.Y, buildingColor)
 					buildingMask.SetPoint(p)
 				}
+				if usedRoadAnchor {
+					anchorUsage[anchor]++
+				}
 				buildings = append(buildings, pixels)
 				buildingsPlaced++
 				break // Move to the next building