Add some isclose

datashader/glyphs/polygon.py

@@ -155,7 +155,10 @@ def draw_polygon(
                 x1c = x_mapper(x1) * sx + tx - 0.5
                 y1c = y_mapper(y1) * sy + ty - 0.5
 
-                if y1c > y0c:
+                if np.isclose(y1c, y0c):
+                    # Skip horizontal edges
+                    continue
+                elif y1c > y0c:
                     xs[ei, 0] = x0c
                     ys[ei, 0] = y0c
                     xs[ei, 1] = x1c
@@ -199,7 +202,7 @@ def draw_polygon(
                     #       but is kept if upper vertex overlaps
                     if (
                         y0c >= yi
-                        # or y1c > yi  # Create white dots https://github.com/holoviz/datashader/issues/1327
+                        or y1c < yi
                         or (x0c < xi and x1c < xi)
                     ):
                         # Edge not eligible for any remaining pixel in this row
@@ -223,7 +226,7 @@ def draw_polygon(
                         # Compute cross product of B and A
                         bxa = (bx * ay - by * ax)
 
-                        if bxa < 0 or (bxa == 0 and yincreasing[ei]):
+                        if bxa < 0 or (np.isclose(bxa, 0) and yincreasing[ei]):
                             # Edge to the right
                             winding_number += yincreasing[ei]
                         else: