[orx-fx] Directional blur tweaks (#357)

orx-fx/src/jvmDemo/kotlin/DemoDirectionalDisplace02.kt

@@ -0,0 +1,45 @@
+import org.openrndr.application
+import org.openrndr.color.ColorRGBa
+import org.openrndr.color.rgb
+import org.openrndr.draw.ColorType
+import org.openrndr.draw.colorBuffer
+import org.openrndr.draw.loadImage
+import org.openrndr.drawImage
+import org.openrndr.extra.fx.distort.DirectionalDisplace
+import org.openrndr.math.Polar
+
+/**
+ * Demonstrate how to use [DirectionalDisplace].
+ *
+ * The program draws 12 overlapping translucent circles on the
+ * `direction` color buffer to produce new color combinations
+ * on the overlapping areas. Those colors specify where the
+ * `DirectionalDisplace` effect will sample pixels from.
+ */
+
+fun main() = application {
+    program {
+        val displace = DirectionalDisplace()
+
+        val displaced = colorBuffer(width, height)
+        val direction = drawImage(width, height, type = ColorType.FLOAT32) {
+            clear(ColorRGBa.BLACK)
+            for(x in 0 until 6) {
+                val offset = Polar(x * 60.0).cartesian
+                fill = rgb(offset.y, offset.x, 0.0, 0.3)
+                stroke = null
+
+                val pos = bounds.center - offset * 110.0
+                circle(pos, 120.0)
+                circle(pos, 80.0)
+            }
+        }
+        val image = loadImage("demo-data/images/image-001.png")
+        extend {
+            displace.distance = 250.0
+            displace.apply(arrayOf(image, direction), displaced)
+            drawer.image(displaced)
+            //drawer.image(direction)
+        }
+    }
+}