Add a variable rate shading demo (#852)

3d/variable_rate_shading/project.godot

@@ -0,0 +1,36 @@
+; Engine configuration file.
+; It's best edited using the editor UI and not directly,
+; since the parameters that go here are not all obvious.
+;
+; Format:
+;   [section] ; section goes between []
+;   param=value ; assign values to parameters
+
+config_version=5
+
+[application]
+
+config/name="Variable Rate Shading"
+config/description="This project showcases how to use variable rate shading (VRS) in 3D to improve performance.
+
+Performance metrics are also displayed to evaluate potential performance gains."
+run/main_scene="res://vrs.tscn"
+config/features=PackedStringArray("4.0")
+config/icon="res://icon.webp"
+
+[display]
+
+window/vsync/vsync_mode=0
+window/stretch/mode="canvas_items"
+window/stretch/aspect="expand"
+
+[rendering]
+
+textures/default_filters/anisotropic_filtering_level=4
+vrs/mode=1
+vrs/texture="res://vrs_texture.png"
+textures/quality/screen_space_aa=0
+
+[xr]
+
+shaders/enabled=true