From 4f6c6d5a5820a1c10caa368cba3b8e8ac3818d5d Mon Sep 17 00:00:00 2001
From: Emanuel Rabina <emanuelrabina@gmail.com>
Date: Wed, 7 Feb 2024 23:42:16 +1300
Subject: [PATCH] Calculate and return global transforms

---
 .../graphics/pipeline/RenderPipeline.groovy   |  7 ++--
 .../redhorizon/engine/scenegraph/Node.groovy  | 41 ++++++++++++++++++-
 .../engine/scenegraph/nodes/Sprite.groovy     |  9 ++--
 3 files changed, 50 insertions(+), 7 deletions(-)

diff --git a/redhorizon-engine/source/nz/net/ultraq/redhorizon/engine/graphics/pipeline/RenderPipeline.groovy b/redhorizon-engine/source/nz/net/ultraq/redhorizon/engine/graphics/pipeline/RenderPipeline.groovy
index 28752707..e3f99c0e 100644
--- a/redhorizon-engine/source/nz/net/ultraq/redhorizon/engine/graphics/pipeline/RenderPipeline.groovy
+++ b/redhorizon-engine/source/nz/net/ultraq/redhorizon/engine/graphics/pipeline/RenderPipeline.groovy
@@ -31,6 +31,7 @@ import nz.net.ultraq.redhorizon.engine.graphics.imgui.ChangeEvent
 import nz.net.ultraq.redhorizon.engine.graphics.imgui.ControlsOverlayRenderPass
 import nz.net.ultraq.redhorizon.engine.graphics.imgui.ImGuiLayer
 import nz.net.ultraq.redhorizon.engine.input.InputEventStream
+import nz.net.ultraq.redhorizon.engine.scenegraph.Node
 import nz.net.ultraq.redhorizon.engine.scenegraph.Scene
 
 import org.joml.FrustumIntersection
@@ -211,9 +212,9 @@ class RenderPipeline implements AutoCloseable {
 			// Cull the list of renderable items to those just visible in the scene
 			averageNanos('objectCulling', 1f, logger) { ->
 				visibleElements.clear()
-				def frustumIntersection = new FrustumIntersection(camera.projection * camera.view)
-				scene.accept { element ->
-					if (element instanceof GraphicsElement && frustumIntersection.testPlaneXY(element.bounds)) {
+				var frustumIntersection = new FrustumIntersection(camera.projection * camera.view)
+				scene.accept { Node element ->
+					if (element instanceof GraphicsElement && frustumIntersection.testPlaneXY(element.globalBounds)) {
 						visibleElements << element
 					}
 				}
diff --git a/redhorizon-engine/source/nz/net/ultraq/redhorizon/engine/scenegraph/Node.groovy b/redhorizon-engine/source/nz/net/ultraq/redhorizon/engine/scenegraph/Node.groovy
index 9be55c07..eabf8533 100644
--- a/redhorizon-engine/source/nz/net/ultraq/redhorizon/engine/scenegraph/Node.groovy
+++ b/redhorizon-engine/source/nz/net/ultraq/redhorizon/engine/scenegraph/Node.groovy
@@ -34,7 +34,12 @@ class Node<T extends Node> implements SceneEvents, Scriptable<T>, Visitable {
 	final Rectanglef bounds = new Rectanglef()
 
 	protected Node parent
-	protected final List<Node> children = []
+	protected List<Node> children = []
+
+	private final Rectanglef globalBounds = new Rectanglef()
+	private final Matrix4f globalTransform = new Matrix4f()
+	private final Vector3f globalScale = new Vector3f()
+	private final Vector3f globalTranslate = new Vector3f()
 
 	@Override
 	void accept(SceneVisitor visitor) {
@@ -56,6 +61,40 @@ class Node<T extends Node> implements SceneEvents, Scriptable<T>, Visitable {
 		return this
 	}
 
+	/**
+	 * Return the world-space bounds of this node.  ie: the local bounds, then
+	 * taking into account local and all parent/ancestor transforms along the path
+	 * to this node.
+	 *
+	 * @return
+	 */
+	// TODO: Surely this is inefficient having to calculate this each time? 🤔
+	Rectanglef getGlobalBounds() {
+
+		getGlobalTransform()
+		var scale = globalTransform.getScale(globalScale)
+		var translate = globalTransform.getTranslation(globalTranslate)
+		return globalBounds.set(bounds)
+			.scale(scale.x, scale.y)
+			.translate(translate.x, translate.y)
+	}
+
+	/**
+	 * Get the world-space transform of this node.  ie: the local transform, then
+	 * modified by all of the ancestor transforms along the path to this node.
+	 * The result is stored in the private {@code globalTransform} property, and
+	 * returned.
+	 *
+	 * @return
+	 */
+	// TODO: Surely this is inefficient having to calculate this each time? 🤔
+	private Matrix4f getGlobalTransform() {
+
+		return parent != null ?
+			globalTransform.mul(parent.globalTransform) :
+			globalTransform.set(transform)
+	}
+
 	/**
 	 * An alias for {@link #addChild(Node)}
 	 *
diff --git a/redhorizon-engine/source/nz/net/ultraq/redhorizon/engine/scenegraph/nodes/Sprite.groovy b/redhorizon-engine/source/nz/net/ultraq/redhorizon/engine/scenegraph/nodes/Sprite.groovy
index 69e00727..cbe96916 100644
--- a/redhorizon-engine/source/nz/net/ultraq/redhorizon/engine/scenegraph/nodes/Sprite.groovy
+++ b/redhorizon-engine/source/nz/net/ultraq/redhorizon/engine/scenegraph/nodes/Sprite.groovy
@@ -31,8 +31,6 @@ import nz.net.ultraq.redhorizon.filetypes.ImageFile
 
 import org.joml.primitives.Rectanglef
 
-import groovy.transform.TupleConstructor
-
 /**
  * A simple 2D sprite node.  Contains a texture and coordinate data for what
  * parts of that texture to render (ie: the texture represents a larger sprite
@@ -40,7 +38,6 @@ import groovy.transform.TupleConstructor
  *
  * @author Emanuel Rabina
  */
-@TupleConstructor(includes = ['imageFile'])
 class Sprite extends Node<Sprite> implements GraphicsElement {
 
 	final ImageFile imageFile
@@ -50,6 +47,12 @@ class Sprite extends Node<Sprite> implements GraphicsElement {
 	private Material material
 	private Rectanglef region
 
+	Sprite(ImageFile imageFile) {
+
+		bounds.set(0, 0, imageFile.width, imageFile.height)
+		this.imageFile = imageFile
+	}
+
 	@Override
 	void delete(GraphicsRenderer renderer) {
 	}