Fix edge case where 1px cut off from right of image

Backward loop should remain -1

editor/import/resource_importer_texture_atlas.cpp

@@ -131,7 +131,7 @@ static void _plot_triangle(Vector2 *vertices, const Vector2 &p_offset, bool p_tr
 	int max_y = MIN(y[2], height - p_offset.y - 1);
 	for (int yi = y[0]; yi < max_y; yi++) {
 		if (yi >= 0) {
-			for (int xi = (xf > 0 ? int(xf) : 0); xi < (xt < src_width ? xt : src_width - 1); xi++) {
+			for (int xi = (xf > 0 ? int(xf) : 0); xi < (xt <= src_width ? xt : src_width); xi++) {
 				int px = xi, py = yi;
 				int sx = px, sy = py;
 				sx = CLAMP(sx, 0, src_width - 1);