Add DisplaceBlend filter

orx-fx/src/main/kotlin/distort/DisplaceBlend.kt

@@ -0,0 +1,58 @@
+package org.openrndr.extra.fx.distort
+
+import org.openrndr.draw.*
+import org.openrndr.extra.fx.filterFragmentCode
+import org.openrndr.extra.parameters.BooleanParameter
+import org.openrndr.extra.parameters.Description
+import org.openrndr.extra.parameters.DoubleParameter
+import org.openrndr.math.Vector3
+
+@Description("Perturb")
+class DisplaceBlend : Filter(Shader.createFromCode(filterVertexCode, filterFragmentCode("distort/displace-blend.frag"))) {
+    var seed: Vector3 by parameters
+
+    @DoubleParameter("offset", -1.0, 1.0)
+    var offset: Double by parameters
+
+    @DoubleParameter("gain", 0.0, 4.0)
+    var gain: Double by parameters
+
+    @DoubleParameter("feather", 1.0, 100.0)
+    var feather: Double by parameters
+
+    @DoubleParameter("rotation", -180.0, 180.0)
+    var rotation: Double by parameters
+
+    @DoubleParameter("source opacity", 0.0, 1.0)
+    var sourceOpacity: Double by parameters
+
+    @DoubleParameter("target opacity", 0.0, 1.0)
+    var targetOpacity: Double by parameters
+
+    init {
+        gain = 0.1
+        offset = 0.5
+        rotation = 0.0
+        feather = 1.0
+        sourceOpacity = 1.0
+        targetOpacity = 1.0
+    }
+
+    var bicubicFiltering = true
+    private var intermediate: ColorBuffer? = null
+    override fun apply(source: Array<ColorBuffer>, target: Array<ColorBuffer>) {
+        if (source.size >= 2) {
+            if (target[0] === source[0] || target[0] === source[1]) {
+                if (intermediate == null) {
+                    intermediate = colorBuffer(target[0].width, target[0].height, type = target[0].type, format = target[0].format)
+                }
+            }
+            if (bicubicFiltering && source.isNotEmpty()) {
+                source[0].generateMipmaps()
+                source[0].filter(MinifyingFilter.LINEAR_MIPMAP_LINEAR, MagnifyingFilter.LINEAR)
+            }
+            super.apply(source, arrayOf(intermediate ?: target[0]))
+            intermediate?.copyTo(target[0])
+        }
+    }
+}