Working output

.gitignore

@@ -1,5 +1,6 @@
 .env
 map-dots
+*.png
 
 # If you prefer the allow list template instead of the deny list, see community template:
 # https://github.com/github/gitignore/blob/main/community/Golang/Go.AllowList.gitignore

imaging/circles.go

@@ -8,6 +8,7 @@ import (
 	"git.fjla.uk/fred.boniface/map-dots/data"
 	"git.fjla.uk/fred.boniface/map-dots/log"
 	"github.com/fogleman/gg"
+	"go.uber.org/zap"
 )
 
 func mapCirclesToCanvas(img *image.RGBA, locations []data.LocationData) {
@@ -15,13 +16,14 @@ func mapCirclesToCanvas(img *image.RGBA, locations []data.LocationData) {
 	dc := gg.NewContextForRGBA(img)
 	dc.SetRGB(1, 1, 1) // Set canvas background color (white in this case)
 
-	circleRadius := 4 // Replace with your desired fixed radius
+	//circleRadius := 4 // Replace with your desired fixed radius
 
 	bounds := img.Bounds()
 	canvasWidth := bounds.Max.X - bounds.Min.X
 	canvasHeight := bounds.Max.Y - bounds.Min.Y
+	margin := 0.1
 
-	var minLat, maxLat, minLon, maxLon float64
+	var minLat, maxLat, minLon, maxLon = math.MaxFloat64, -math.MaxFloat64, math.MaxFloat64, -math.MaxFloat64
 	for _, loc := range locations {
 		if loc.Latitude < minLat {
 			minLat = loc.Latitude
@@ -37,22 +39,29 @@ func mapCirclesToCanvas(img *image.RGBA, locations []data.LocationData) {
 		}
 	}
 
-	centerLat := (maxLat + minLat) / 2.0
-	centerLon := (maxLon + minLon) / 2.0
 	latRange := maxLat - minLat
 	lonRange := maxLon - minLon
+	minLat -= latRange * margin
+	maxLat += latRange * margin
+	minLon -= lonRange * margin
+	maxLon += lonRange * margin
+
+	minLatEqui := equirectangularProjection(minLat)
+	maxLatEqui := equirectangularProjection(maxLat)
+
+	latScale := float64(canvasHeight) / (maxLatEqui - minLatEqui)
+	longScale := float64(canvasWidth) / (maxLon - minLon)
 
 	for _, loc := range locations {
-		pixelX, pixelY := convertCoordinatesToPixels(loc.Latitude, loc.Longitude, centerLat, centerLon, latRange, lonRange, canvasWidth, canvasHeight)
+		x := int((loc.Longitude - minLon) * longScale)
-
+		// Invert the Y-axis calculation
-		// Draw the circle on the canvas using gg
+		y := canvasHeight - int((equirectangularProjection(loc.Latitude)-minLatEqui)*latScale)
-		dc.DrawCircle(float64(pixelX), float64(pixelY), float64(circleRadius))
+		// Draw a dot (circle) at (x, y)
-		dc.SetRGBA(1, 1, 1, 0.5) // Circle fill color (white with 50% opacity)
+		dc.DrawCircle(float64(x), float64(y), 2)
+		dc.SetRGBA(1, 1, 1, 0.3333333333) // Set dot color (black)
 		dc.Fill()
 	}
 
-	dc.Clip() // Apply clipping
-
 	// Optional: Save the canvas as an image file
 	err := dc.SavePNG("output.png")
 	if err != nil {
@@ -60,6 +69,9 @@ func mapCirclesToCanvas(img *image.RGBA, locations []data.LocationData) {
 	} else {
 		fmt.Println("Canvas saves to file")
 	}
+
+	fmt.Println(minLat)
+	fmt.Println(minLon)
 }
 
 func convertCoordinatesToPixels(latitude, longitude float64, centerLat, centerLon, latRange, lonRange float64, canvasWidth, canvasHeight int) (int, int) {
@@ -80,3 +92,8 @@ func convertCoordinatesToPixels(latitude, longitude float64, centerLat, centerLo
 
 	return pixelX, pixelY
 }
+
+func equirectangularProjection(lat float64) float64 {
+	log.Msg.Debug("Running equirectangular calculation", zap.Float64("lat", lat))
+	return lat * (math.Pi / 180) // Convert degrees to radians
+}