[openrndr-demos] Add rectangle batch demos

openrndr-demos/src/demo/kotlin/DrawerRectangleBatch03.kt

@@ -0,0 +1,23 @@
+// Dynamic rectangle batches
+
+import org.openrndr.application
+import org.openrndr.color.ColorRGBa
+
+fun main() = application {
+    program {
+        extend {
+            drawer.clear(ColorRGBa.GRAY)
+            drawer.fill = ColorRGBa.PINK
+            drawer.stroke = ColorRGBa.WHITE
+            drawer.strokeWeight = 2.0
+            drawer.rectangles {
+                for (y in 0 until height/20) {
+                    for (x in 0 until width/20) {
+                        rectangle(x * 20.0, y * 20.0, 10.0, 15.0, (x + y) * 10.0 + seconds*90.0)
+
+                    }
+                }
+            }
+        }
+    }
+}