From 240bfa8ed5022627de0d4b256c67296fd2211f1a Mon Sep 17 00:00:00 2001
From: Relintai <relintai@protonmail.com>
Date: Sun, 20 Nov 2022 02:35:02 +0100
Subject: [PATCH] Rewrote render_paint_node now it works without leaving pixels
 out, but it is an extermely inefficient implementation. It will be reworked
 soon.

---
 modules/paint/nodes/paint_node.cpp | 63 ++++++++++++++++++++++++------
 1 file changed, 50 insertions(+), 13 deletions(-)

diff --git a/modules/paint/nodes/paint_node.cpp b/modules/paint/nodes/paint_node.cpp
index 07ad1e60a..928832ac6 100644
--- a/modules/paint/nodes/paint_node.cpp
+++ b/modules/paint/nodes/paint_node.cpp
@@ -1,6 +1,7 @@
 #include "paint_node.h"
 
 #include "../paint_utilities.h"
+#include "core/math/geometry.h"
 #include "paint_project.h"
 
 Vector2i PaintNode::get_size() {
@@ -106,24 +107,60 @@ void PaintNode::render_paint_node(PaintNode *node, Transform2D transform, Ref<Im
 	Vector2i save_image_size = save_image->get_size();
 	Vector2i image_size = image->get_size();
 
+	// NOTE: this is EXTREMELY inefficient, and slow, however it does work for now.
+	// It will be rewritten soon.
+
+	Vector2 p0 = transform.xform(Vector2(0, 0));
+	Vector2 p1 = transform.xform(Vector2(0, save_image_size.y));
+	Vector2 p2 = transform.xform(Vector2(save_image_size.x, 0));
+	Vector2 p3 = transform.xform(Vector2(save_image_size.x, save_image_size.y));
+
+	Vector<Point2i> queued_points = Geometry::brenzenham_line(p0.x, p1.x, p0.y, p1.y);
+	queued_points.append_array(Geometry::brenzenham_line(p1.x, p3.x, p1.y, p3.y));
+	queued_points.append_array(Geometry::brenzenham_line(p2.x, p3.x, p2.y, p3.y));
+	queued_points.append_array(Geometry::brenzenham_line(p0.x, p2.x, p0.y, p2.y));
+
+	Vector<Point2i> points_to_check;
+
+	for (int i = 0; i < queued_points.size(); ++i) {
+		Point2i p = queued_points[i];
+
+		Vector<Point2i> points = Geometry::brenzenham_line(p0.x, p.x, p0.y, p.y);
+		points.append_array(Geometry::brenzenham_line(p3.x, p.x, p3.y, p.y));
+		points.append_array(Geometry::brenzenham_line(p2.x, p.x, p2.y, p.y));
+		points.append_array(Geometry::brenzenham_line(p1.x, p.x, p1.y, p.y));
+
+		for (int j = 0; j < points.size(); ++j) {
+			Point2i pc = points[j];
+
+			if (points_to_check.find(pc) == -1) {
+				points_to_check.push_back(pc);
+			}
+		}
+	}
+
+	Transform2D inverse = transform.affine_inverse();
+
 	save_image->lock();
 	image->lock();
 
-	//should return early eventually via a simple overlap check here
+	for (int i = 0; i < points_to_check.size(); ++i) {
+		Point2i p = points_to_check[i];
 
-	for (int x = 0; x < save_image_size.x; ++x) {
-		for (int y = 0; y < save_image_size.y; ++y) {
-			Vector2i npos = transform.xform(Vector2(x, y));
-
-			if (npos.x < 0 || npos.y < 0 || npos.x >= image_size.x || npos.y >= image_size.y) {
-				continue;
-			}
-
-			Color sic = save_image->get_pixel(x, y);
-			Color oic = image->get_pixel(npos.x, npos.y);
-
-			image->set_pixel(npos.x, npos.y, oic.blend(sic));
+		if (p.x < 0 || p.y < 0 || p.x >= image_size.x || p.y >= image_size.y) {
+			continue;
 		}
+
+		Vector2 npos = inverse.xform(Vector2(p.x, p.y));
+
+		if (npos.x < 0 || npos.y < 0 || npos.x >= save_image_size.x || npos.y >= save_image_size.y) {
+			continue;
+		}
+
+		Color sic = save_image->get_pixel(npos.x, npos.y);
+		Color oic = image->get_pixel(p.x, p.y);
+
+		image->set_pixel(p.x, p.y, oic.blend(sic));
 	}
 
 	image->unlock();