fix

Co-authored-by: Pierre-Yves Rollo <dev@pyrollo.com>

mapblockrenderer/renderer.go

@@ -73,6 +73,31 @@ func addColorComponent(c *color.RGBA, value int) *color.RGBA {
 	}
 }
 
+func clamp_ratio(ratio float32) float32 {
+	if ratio < 0 {
+		return 0
+	}
+
+	if ratio > 1 {
+		return 1
+	}
+
+	return ratio
+}
+
+func interp_value(min uint8, max uint8, ratio float32) uint8 {
+	return min + uint8(float32(max-min)*clamp_ratio(ratio))
+}
+
+func blend_colors(lower color.RGBA, upper color.RGBA) (blended color.RGBA) {
+	ratio := float32(upper.A) / float32(255)
+	blended.R = interp_value(lower.R, upper.R, ratio)
+	blended.G = interp_value(lower.G, upper.G, ratio)
+	blended.B = interp_value(lower.B, upper.B, ratio)
+	blended.A = 255
+	return
+}
+
 func (r *MapBlockRenderer) Render(pos1, pos2 *types.MapBlockCoords) (*image.NRGBA, error) {
 	if pos1.X != pos2.X {
 		return nil, errors.New("x does not line up")
@@ -124,6 +149,8 @@ func (r *MapBlockRenderer) Render(pos1, pos2 *types.MapBlockCoords) (*image.NRGB
 
 		for x := 0; x < 16; x++ {
 			for z := 0; z < 16; z++ {
+				var colors_stack [16]color.RGBA
+				var visible_nodes_count uint8 = 0
 				for y := 15; y >= 0; y-- {
 					if xzOccupationMap[x][z] {
 						break
@@ -142,9 +169,6 @@ func (r *MapBlockRenderer) Render(pos1, pos2 *types.MapBlockCoords) (*image.NRGB
 						continue
 					}
 
-					// clamp alpha channel to max
-					c.A = 255
-
 					if r.enableShadow {
 						var left, leftAbove, top, topAbove string
 
@@ -209,10 +233,32 @@ func (r *MapBlockRenderer) Render(pos1, pos2 *types.MapBlockCoords) (*image.NRGB
 						}
 					}
 
+					colors_stack[visible_nodes_count] = *c
+					visible_nodes_count++
+
+					if c.A == 0xFF || !r.enableTransparency {
+						//not transparent, mark as rendered
+						foundBlocks++
+						xzOccupationMap[x][z] = true
+					}
+				}
+
+				if visible_nodes_count == 0 {
+					continue
+				}
+
+				visible_nodes_count--
+				result_color := colors_stack[visible_nodes_count]
+				if visible_nodes_count > 0 {
+					for layer := visible_nodes_count; layer > 0; layer-- {
+						result_color = blend_colors(result_color, colors_stack[layer-1])
+					}
+				}
+
 				imgX := x * IMG_SCALE
 				imgY := (15 - z) * IMG_SCALE
 
-					r32, g32, b32, a32 := c.RGBA()
+				r32, g32, b32, a32 := result_color.RGBA()
 				r8, g8, b8, a8 := uint8(r32), uint8(g32), uint8(b32), uint8(a32)
 				for Y := imgY; Y < imgY+IMG_SCALE; Y++ {
 					ix := (Y*IMG_SIZE + imgX) << 2
@@ -228,19 +274,12 @@ func (r *MapBlockRenderer) Render(pos1, pos2 *types.MapBlockCoords) (*image.NRGB
 					}
 				}
 
-					if c.A != 0xFF || !r.enableTransparency {
-						//not transparent, mark as rendered
-						foundBlocks++
-						xzOccupationMap[x][z] = true
-					}
-
 				if foundBlocks == EXPECTED_BLOCKS_PER_FLAT_MAPBLOCK {
 					return img, nil
 				}
 			}
 		}
 	}
-	}
 
 	if foundBlocks == 0 {
 		return nil, nil

public/js/components/LayerSelector.js

@@ -7,9 +7,11 @@ function onchange(e){
   m.route.set("/map/:layerId/:zoom/:lon/:lat", params);
 }
 
-
 export default {
   view: function(){
+    // Display layer selector only if there is choice
+    if (LayerManager.layers.length <= 1)
+      return null;
 
     const layers = LayerManager.layers.map(layer => m(
       "option",

public/js/map/overlays/TrainOverlay.js

@@ -71,7 +71,7 @@ export default L.LayerGroup.extend({
 
 
   getMaxDisplayedZoom: function(){
-    return 10;
+    return 7;
   },
 
   createMarker: function(train){

public/js/map/overlays/TrainlineOverlay.js

@@ -59,6 +59,10 @@ export default AbstractGeoJsonOverlay.extend({
     });
   },
 
+  getMaxDisplayedZoom: function(){
+    return 4;
+  },
+  
   createGeoJson: function(objects){
     var self = this;