Add a global illumination demo

Port of the 3.x global illumination demo, with SDFGI support added
and screen-space lighting effect options added (SSAO, SSIL, or both).

Lightmap options were removed as I couldn't get both indirect-only
and fully baked lightmaps to work for now. They can be readded in the
future.

3d/global_illumination/README.md

@@ -1,39 +1,21 @@
 # Global Illumination
 
 This demo showcases Godot's global illumination systems:
-[GIProbe](https://docs.godotengine.org/en/stable/tutorials/3d/gi_probes.html),
-[BakedLightmap](https://docs.godotengine.org/en/stable/tutorials/3d/baked_lightmaps.html)
-(indirect only and fully baked) and
-[ReflectionProbe](https://docs.godotengine.org/en/stable/tutorials/3d/reflection_probes.html).
+VoxelGI, SDFGI, ReflectionProbe and screen-space effects like SSAO and SSIL.
 
 Use the mouse to look around, <kbd>W</kbd>/<kbd>A</kbd>/<kbd>S</kbd>/<kbd>D</kbd>
 or arrow keys to move.
 
 Language: GDScript
 
-Renderer: GLES 3[^1]
-
-Check out this demo on the asset library: https://godotengine.org/asset-library/asset/1290
+Renderer: Vulkan
 
 ## How does it work?
 
-A glTF scene (which acts as the level mesh) is imported with its **Light Baking**
-option set to **Gen Lightmaps**.
-This is required for BakedLightmap to work (but is not required for GIProbe
-or BakedLightmap).
-
-The level mesh is duplicated several times to allow displaying it with various bake settings:
-
-- No baking (uses GIProbe or environment lighting).
-- Baked indirect lighting. Slower, but allows for real-time shadows to display
-  on baked surfaces.
-- Baked direct *and* indirect lighting. Faster, but does not allow for real-time
-  shadows to display on baked surfaces.
-
 A sphere and box are parented to the camera to showcase dynamic object lighting.
 A ReflectionProbe is parented to the sphere to showcase real-time reflections.
 When the ReflectionProbe is hidden, it is disabled. In this case,
-GIProbe or environment lighting will be used to provide fallback reflections.
+VoxelGI, SDFGI or environment lighting will be used to provide fallback reflections.
 
 ## Screenshots
 
@@ -45,7 +27,3 @@ GIProbe or environment lighting will be used to provide fallback reflections.
 map "zdm2" and is
 [licensed under CC BY 4.0 Unported](https://github.com/Calinou/game-maps-obj/blob/master/sauerbraten/zdm2.txt).
 The OBJ file which it was converted from is available in the [game-maps-obj](https://github.com/Calinou/game-maps-obj) repository.
-
-[^1]: This demo can be made to work with GLES2, but GIProbe will not work.
-Additionally, lightmaps have to be rebaked with the **Atlas > Generate** property
-disabled in BakedLightmap.

3d/global_illumination/camera.gd

@@ -1,4 +1,4 @@
-extends Camera
+extends Camera3D
 
 const MOUSE_SENSITIVITY = 0.002
 const MOVE_SPEED = 1.5
@@ -18,7 +18,7 @@ func _input(event):
 		rot.y -= event.relative.x * MOUSE_SENSITIVITY
 		# Vertical mouse look.
 		rot.x = clamp(rot.x - event.relative.y * MOUSE_SENSITIVITY, -1.57, 1.57)
-		transform.basis = Basis(rot)
+		transform.basis = Basis.from_euler(rot)
 
 	if event.is_action_pressed("toggle_mouse_capture"):
 		if Input.get_mouse_mode() == Input.MOUSE_MODE_CAPTURED:
@@ -38,6 +38,6 @@ func _process(delta):
 	# `sqrt(2)` times faster than straight movement.
 	motion = motion.normalized()
 
-	velocity += MOVE_SPEED * delta * transform.basis.xform(motion)
+	velocity += MOVE_SPEED * delta * (transform.basis * motion)
 	velocity *= 0.85
-	translation += velocity
+	position += velocity