Add orx-fx, the new home for what was in openrndr-filter before

orx-fx/src/main/kotlin/blur/ApproximateGaussianBlur.kt

@@ -0,0 +1,66 @@
+package org.openrndr.extra.fx.blur
+
+import org.openrndr.draw.ColorBuffer
+import org.openrndr.draw.Filter
+import org.openrndr.draw.Shader
+import org.openrndr.draw.colorBuffer
+import org.openrndr.extra.fx.filterFragmentCode
+
+import org.openrndr.math.Vector2
+
+/**
+ * Approximate separated Gaussian blur
+ */
+class ApproximateGaussianBlur : Filter(Shader.createFromCode(Filter.filterVertexCode,
+        filterFragmentCode("blur/approximate-gaussian-blur.frag"))) {
+
+    /**
+     * blur sample window, default value is 5
+     */
+    var window: Int by parameters
+
+    /**
+     * spread multiplier, default value is 1.0
+     */
+    var spread: Double by parameters
+
+    /**
+     * blur sigma, default value is 1.0
+     */
+    var sigma: Double by parameters
+
+    /**
+     * post blur gain, default value is 1.0
+     */
+    var gain: Double by parameters
+
+
+    private var intermediate: ColorBuffer? = null
+
+    init {
+        window = 5
+        spread = 1.0
+        gain = 1.0
+        sigma = 1.0
+    }
+
+    override fun apply(source: Array<ColorBuffer>, target: Array<ColorBuffer>) {
+        intermediate?.let {
+            if (it.width != target[0].width || it.height != target[0].height) {
+                intermediate = null
+            }
+        }
+
+        if (intermediate == null) {
+            intermediate = colorBuffer(target[0].width, target[0].height, target[0].contentScale, target[0].format, target[0].type)
+        }
+
+        intermediate?.let {
+            parameters["blurDirection"] = Vector2(1.0, 0.0)
+            super.apply(source, arrayOf(it))
+
+            parameters["blurDirection"] = Vector2(0.0, 1.0)
+            super.apply(arrayOf(it), target)
+        }
+    }
+}