Created the split pattern

artist/split.go

@@ -0,0 +1,43 @@
+package artist
+
+import "image/color"
+
+// Orientation specifies an eight-way pattern orientation.
+type Orientation int
+
+const (
+	OrientationVertical Orientation = iota
+	OrientationDiagonalRight
+	OrientationHorizontal
+	OrientationDiagonalLeft
+)
+
+// Split is a pattern that is divided in half between two sub-patterns.
+type Split struct {
+	First  Pattern
+	Second Pattern
+	Orientation
+}
+
+// AtWhen satisfies the Pattern interface.
+func (pattern Split) AtWhen (x, y, width, height int) (c color.RGBA) {
+	var first bool
+	switch pattern.Orientation {
+	case OrientationVertical:
+		first = x < width / 2
+	case OrientationDiagonalRight:
+		first = float64(x) / float64(width) +
+			float64(y) / float64(height) < 1
+	case OrientationHorizontal:
+		first = y < height / 2
+	case OrientationDiagonalLeft:
+		first = float64(width - x) / float64(width) +
+			float64(y) / float64(height) < 1
+	}
+	
+	if first {
+		return pattern.First.AtWhen(x, y, width, height)
+	} else {
+		return pattern.Second.AtWhen(x, y, width, height)
+	}
+}

artist/striped.go

@@ -2,34 +2,24 @@ package artist
 
 import "image/color"
 
-// StripeDirection specifies the direction of stripes.
-type StripeDirection int
-
-const (
-	StripeDirectionVertical StripeDirection = iota
-	StripeDirectionDiagonalRight
-	StripeDirectionHorizontal
-	StripeDirectionDiagonalLeft
-)
-
 // Striped is a pattern that produces stripes of two alternating colors.
 type Striped struct {
-	First     Stroke
-	Second    Stroke
-	Direction StripeDirection
+	First  Stroke
+	Second Stroke
+	Orientation
 }
 
 // AtWhen satisfies the Pattern interface.
 func (pattern Striped) AtWhen (x, y, width, height int) (c color.RGBA) {
 	position := 0
-	switch pattern.Direction {
-	case StripeDirectionVertical:
+	switch pattern.Orientation {
+	case OrientationVertical:
 		position = x
-	case StripeDirectionDiagonalRight:
+	case OrientationDiagonalRight:
 		position = x + y
-	case StripeDirectionHorizontal:
+	case OrientationHorizontal:
 		position = y
-	case StripeDirectionDiagonalLeft:
+	case OrientationDiagonalLeft:
 		position = x - y
 	}
 
@@ -40,8 +30,8 @@ func (pattern Striped) AtWhen (x, y, width, height int) (c color.RGBA) {
 	}
 	
 	if position < pattern.First.Weight {
-		return pattern.First.Pattern.AtWhen(x, y, width, height)
+		return pattern.First.AtWhen(x, y, width, height)
 	} else {
-		return pattern.Second.Pattern.AtWhen(x, y, width, height)
+		return pattern.Second.AtWhen(x, y, width, height)
 	}
 }

elements/testing/artist.go

@@ -75,7 +75,7 @@ func (element *Artist) Resize (width, height int) {
 			artist.Striped {
 				First:  artist.Stroke { Pattern: uhex(0xFF8800FF), Weight: 7 },
 				Second: artist.Stroke { Pattern: uhex(0x0088FFFF), Weight: 2 },
-				Direction: artist.StripeDirection(x),
+				Orientation: artist.Orientation(x),
 				
 			},
 			element.cellAt(x, 1))
@@ -107,14 +107,17 @@ func (element *Artist) Resize (width, height int) {
 			x, element.cellAt(x, 3))
 	}
 
-	// 0, 4
-	artist.FillEllipse (
-		element, 
-		artist.Beveled {
-			Highlight: artist.NewUniform(hex(0xFF0000FF)),
-			Shadow:    artist.NewUniform(hex(0x0000FFFF)),
-		},
-		element.cellAt(0, 4))
+	// 0, 4 - 3, 4
+	for x := 0; x < 4; x ++ {
+		artist.FillEllipse (
+			element, 
+			artist.Split {
+				First:  artist.NewUniform(hex(0xFF0000FF)),
+				Second: artist.NewUniform(hex(0x0000FFFF)),
+				Orientation: artist.Orientation(x),
+			},
+			element.cellAt(x, 4))
+	}
 	
 	// how long did that take to render?
 	drawTime := time.Since(drawStart)