Add compute texture demo

compute/texture/README.md

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+# Compute texture
+
+This demo shows how to use compute shaders to populate a texture that is used as an input for a material shader.
+
+When the mouse cursor isn't hovering above the plane random "drops" of water are added that drive the ripple effect.
+When the mouse cursor is above the plane you can "draw" on the plane to drive the ripple effect.
+
+Language: GDScript
+
+Renderer: Forward Plus
+
+> Note: this demo requires Godot 4.2 or later
+
+## Screenshots
+
+![Screenshot](screenshots/compute_texture.webp)
+
+## Technical description
+
+The texture populated by the compute shader contains height data that is used in the material shader to create a rain drops/water ripple effect. It's a well known technique that has been around since the mid 90ies, adapted to a compute shader.
+
+Three textures are created directly on the rendering device:
+- One texture is used to write the heightmap to and used in the material shader.
+- One texture is read from and contains the previous frames data.
+- One texture is read from and contains data from the frame before that.
+
+Instead of copying data from texture to texture to create this history, we simply cycle the RIDs.
+
+Note that in this demo we are using the main rendering device to ensure we execute our compute shader before our normal rendering.
+
+To use the texture with the latest height data we use a `Texture2DRD` resource, this is a special texture resource node that is able to use a texture directly created on the rendering device and expose it to material shaders.
+
+The material shader uses a standard gradient approach by sampling the height map and calculating tangent and bi-normal vectors and adjust the normal accordingly.
+
+## Licenses
+
+Files in the `polyhaven/` folder are downloaded from <https://polyhaven.com/a/industrial_sunset_puresky>
+and are licensed under CC0 1.0 Universal.

compute/texture/assets/polyhaven/industrial_sunset_puresky_2k.hdr.import

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+[remap]
+
+importer="texture"
+type="CompressedTexture2D"
+uid="uid://d051ugdf65it1"
+path="res://.godot/imported/industrial_sunset_puresky_2k.hdr-2273dddf6859dd4da64c4a85b4589512.ctex"
+metadata={
+"vram_texture": false
+}
+
+[deps]
+
+source_file="res://assets/polyhaven/industrial_sunset_puresky_2k.hdr"
+dest_files=["res://.godot/imported/industrial_sunset_puresky_2k.hdr-2273dddf6859dd4da64c4a85b4589512.ctex"]
+
+[params]
+
+compress/mode=3
+compress/high_quality=false
+compress/lossy_quality=0.7
+compress/hdr_compression=1
+compress/normal_map=0
+compress/channel_pack=0
+mipmaps/generate=false
+mipmaps/limit=-1
+roughness/mode=0
+roughness/src_normal=""
+process/fix_alpha_border=true
+process/premult_alpha=false
+process/normal_map_invert_y=false
+process/hdr_as_srgb=false
+process/hdr_clamp_exposure=false
+process/size_limit=0
+detect_3d/compress_to=0

compute/texture/icon.svg.import

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+[remap]
+
+importer="texture"
+type="CompressedTexture2D"
+uid="uid://bonkdv3wikslq"
+path="res://.godot/imported/icon.svg-218a8f2b3041327d8a5756f3a245f83b.ctex"
+metadata={
+"vram_texture": false
+}
+
+[deps]
+
+source_file="res://icon.svg"
+dest_files=["res://.godot/imported/icon.svg-218a8f2b3041327d8a5756f3a245f83b.ctex"]
+
+[params]
+
+compress/mode=0
+compress/high_quality=false
+compress/lossy_quality=0.7
+compress/hdr_compression=1
+compress/normal_map=0
+compress/channel_pack=0
+mipmaps/generate=false
+mipmaps/limit=-1
+roughness/mode=0
+roughness/src_normal=""
+process/fix_alpha_border=true
+process/premult_alpha=false
+process/normal_map_invert_y=false
+process/hdr_as_srgb=false
+process/hdr_clamp_exposure=false
+process/size_limit=0
+detect_3d/compress_to=1
+svg/scale=1.0
+editor/scale_with_editor_scale=false
+editor/convert_colors_with_editor_theme=false

compute/texture/main.gd

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+extends Node3D
+
+# Note, the code here just adds some control to our effects.
+# Check res://water_plane/water_plane.gd for the real implementation
+
+var y = 0.0
+
+@onready var water_plane = $WaterPlane
+
+func _ready():
+	$Container/RainSize/HSlider.value = $WaterPlane.rain_size
+	$Container/MouseSize/HSlider.value = $WaterPlane.mouse_size
+
+
+# Called every frame. 'delta' is the elapsed time since the previous frame.
+func _process(delta):
+	if $Container/Rotate.button_pressed:
+		y += delta
+		water_plane.basis = Basis(Vector3.UP, y)
+
+
+func _on_rain_size_changed(value):
+	$WaterPlane.rain_size = value
+
+
+func _on_mouse_size_changed(value):
+	$WaterPlane.mouse_size = value

compute/texture/main.tscn

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+[gd_scene load_steps=7 format=3 uid="uid://c7nfvt1chslyh"]
+
+[ext_resource type="Script" path="res://main.gd" id="1_yvrvl"]
+[ext_resource type="Texture2D" uid="uid://d051ugdf65it1" path="res://assets/polyhaven/industrial_sunset_puresky_2k.hdr" id="2_g2q6b"]
+[ext_resource type="PackedScene" uid="uid://b2a5bjsxw63wr" path="res://water_plane/water_plane.tscn" id="2_k1nfp"]
+
+[sub_resource type="PanoramaSkyMaterial" id="PanoramaSkyMaterial_obhcg"]
+panorama = ExtResource("2_g2q6b")
+
+[sub_resource type="Sky" id="Sky_s1sgk"]
+sky_material = SubResource("PanoramaSkyMaterial_obhcg")
+
+[sub_resource type="Environment" id="Environment_5dv8s"]
+background_mode = 2
+sky = SubResource("Sky_s1sgk")
+tonemap_mode = 2
+tonemap_white = 4.56
+
+[node name="Main" type="Node3D"]
+script = ExtResource("1_yvrvl")
+
+[node name="DirectionalLight3D" type="DirectionalLight3D" parent="."]
+transform = Transform3D(0.5, -0.75, 0.433013, 2.78059e-08, 0.5, 0.866026, -0.866025, -0.433013, 0.25, 0, 1, 0)
+shadow_enabled = true
+
+[node name="WorldEnvironment" type="WorldEnvironment" parent="."]
+environment = SubResource("Environment_5dv8s")
+
+[node name="WaterPlane" parent="." instance=ExtResource("2_k1nfp")]
+
+[node name="Camera3D" type="Camera3D" parent="."]
+transform = Transform3D(0.900266, -0.142464, 0.41137, -0.113954, 0.834877, 0.538512, -0.420162, -0.531681, 0.735377, 1.55343, 1.1434, 2.431)
+
+[node name="Container" type="VBoxContainer" parent="."]
+offset_right = 40.0
+offset_bottom = 40.0
+
+[node name="Rotate" type="CheckBox" parent="Container"]
+layout_mode = 2
+theme_override_colors/font_color = Color(0, 0, 0, 1)
+text = "Rotate"
+
+[node name="RainSize" type="HBoxContainer" parent="Container"]
+layout_mode = 2
+
+[node name="HSlider" type="HSlider" parent="Container/RainSize"]
+custom_minimum_size = Vector2(250, 0)
+layout_mode = 2
+min_value = 1.0
+max_value = 10.0
+step = 0.1
+value = 1.0
+
+[node name="Label" type="Label" parent="Container/RainSize"]
+layout_mode = 2
+theme_override_colors/font_color = Color(0, 0, 0, 1)
+text = "Rain size"
+
+[node name="MouseSize" type="HBoxContainer" parent="Container"]
+layout_mode = 2
+
+[node name="HSlider" type="HSlider" parent="Container/MouseSize"]
+custom_minimum_size = Vector2(250, 0)
+layout_mode = 2
+min_value = 1.0
+max_value = 10.0
+step = 0.1
+value = 1.1
+
+[node name="Label" type="Label" parent="Container/MouseSize"]
+layout_mode = 2
+theme_override_colors/font_color = Color(0, 0, 0, 1)
+text = "Mouse size"
+
+[connection signal="value_changed" from="Container/RainSize/HSlider" to="." method="_on_rain_size_changed"]
+[connection signal="value_changed" from="Container/MouseSize/HSlider" to="." method="_on_mouse_size_changed"]

compute/texture/project.godot

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+; 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="TestCustomTextures"
+run/main_scene="res://main.tscn"
+config/features=PackedStringArray("4.2", "Forward Plus")
+config/icon="res://icon.svg"
+
+[rendering]
+
+driver/threads/thread_model=2

compute/texture/water_plane/water_compute.glsl

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+#[compute]
+#version 450
+
+// Invocations in the (x, y, z) dimension
+layout(local_size_x = 8, local_size_y = 8, local_size_z = 1) in;
+
+// Our textures
+layout(r32f, set = 0, binding = 0) uniform restrict readonly image2D current_image;
+layout(r32f, set = 1, binding = 0) uniform restrict readonly image2D previous_image;
+layout(r32f, set = 2, binding = 0) uniform restrict writeonly image2D output_image;
+
+// Our push PushConstant
+layout(push_constant, std430) uniform Params {
+	vec4 add_wave_point;
+	vec2 texture_size;
+	float damp;
+	float res2;
+} params;
+
+// The code we want to execute in each invocation
+void main() {
+	ivec2 tl = ivec2(0, 0);
+	ivec2 size = ivec2(params.texture_size.x - 1, params.texture_size.y - 1);
+
+	ivec2 uv = ivec2(gl_GlobalInvocationID.xy);
+
+	float current_v = imageLoad(current_image, uv).r;
+	float up_v = imageLoad(current_image, clamp(uv - ivec2(0, 1), tl, size)).r;
+	float down_v = imageLoad(current_image, clamp(uv + ivec2(0, 1), tl, size)).r;
+	float left_v = imageLoad(current_image, clamp(uv - ivec2(1, 0), tl, size)).r;
+	float right_v = imageLoad(current_image, clamp(uv + ivec2(1, 0), tl, size)).r;
+	float previous_v = imageLoad(previous_image, uv).r;
+
+	float new_v = 2.0 * current_v - previous_v + 0.25 * (up_v + down_v + left_v + right_v - 4.0 * current_v);
+	new_v = new_v - (params.damp * new_v * 0.001);
+
+	if (params.add_wave_point.z > 0.0 && uv.x == floor(params.add_wave_point.x) && uv.y == floor(params.add_wave_point.y)) {
+		new_v = params.add_wave_point.z;
+	}
+
+	if (new_v < 0.0) {
+		new_v = 0.0;
+	}
+	vec4 result = vec4(new_v, new_v, new_v, 1.0);
+
+	imageStore(output_image, uv, result);
+}

compute/texture/water_plane/water_compute.glsl.import

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+[remap]
+
+importer="glsl"
+type="RDShaderFile"
+uid="uid://b6pdquh2n2jvn"
+path="res://.godot/imported/water_compute.glsl-c7fe8f11197ba28412c4cdf6f7a9a21b.res"
+
+[deps]
+
+source_file="res://water_plane/water_compute.glsl"
+dest_files=["res://.godot/imported/water_compute.glsl-c7fe8f11197ba28412c4cdf6f7a9a21b.res"]
+
+[params]
+