Added orx-no-clear

orx-no-clear/src/main/kotlin/NoClear.kt

@@ -0,0 +1,45 @@
+import org.openrndr.Extension
+import org.openrndr.Program
+import org.openrndr.color.ColorRGBa
+import org.openrndr.draw.Drawer
+import org.openrndr.draw.RenderTarget
+import org.openrndr.draw.isolated
+import org.openrndr.draw.renderTarget
+
+class NoClear : Extension {
+    override var enabled: Boolean = true
+    private var renderTarget: RenderTarget? = null
+
+
+    override fun beforeDraw(drawer: Drawer, program: Program) {
+        if (renderTarget == null || renderTarget?.width != program.width || renderTarget?.height != program.height) {
+            renderTarget?.let {
+                it.colorBuffer(0).destroy()
+                it.detachColorBuffers()
+                it.destroy()
+            }
+            renderTarget = renderTarget(program.width, program.height) {
+                colorBuffer()
+                depthBuffer()
+            }
+
+            renderTarget?.let {
+                drawer.withTarget(it) {
+                    background(program.backgroundColor ?: ColorRGBa.TRANSPARENT)
+                }
+            }
+        }
+        renderTarget?.bind()
+    }
+
+    override fun afterDraw(drawer: Drawer, program: Program) {
+        renderTarget?.unbind()
+
+        renderTarget?.let {
+            drawer.isolated {
+                drawer.ortho()
+                drawer.image(it.colorBuffer(0))
+            }
+        }
+    }
+}