Add screenshot generation

orx-shade-styles/build.gradle

@@ -11,6 +11,7 @@ dependencies {
     api project(":orx-parameters")
 
     demoImplementation("org.openrndr:openrndr-core:$openrndrVersion")
+    demoImplementation("org.openrndr:openrndr-extensions:$openrndrVersion")
     demoRuntimeOnly("org.openrndr:openrndr-gl3:$openrndrVersion")
     demoRuntimeOnly("org.openrndr:openrndr-gl3-natives-$openrndrOS:$openrndrVersion")
     demoImplementation(sourceSets.getByName("main").output)

orx-shade-styles/src/demo/kotlin/DemoRadialGradient01.kt

@@ -1,5 +1,6 @@
 import org.openrndr.application
 import org.openrndr.color.ColorRGBa
+import org.openrndr.extensions.SingleScreenshot
 
 import org.openrndr.extra.shadestyles.radialGradient
 import kotlin.math.cos
@@ -7,6 +8,11 @@ import kotlin.math.cos
 fun main() {
     application {
         program {
+            if (System.getProperty("takeScreenshot") == "true") {
+                extend(SingleScreenshot()) {
+                    this.outputFile = System.getProperty("screenshotPath")
+                }
+            }
             extend {
                 drawer.shadeStyle = radialGradient(
                         ColorRGBa.PINK,