[DRAFT] Add HDR output demo

hdr_output/color_sweep/color_sweep.tscn

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+[gd_scene format=3 uid="uid://drlb4o61s5wsk"]
+
+[ext_resource type="Script" uid="uid://cqjmg63jbxlns" path="res://color_sweep/colour_sweep.gd" id="1_3qbqk"]
+[ext_resource type="Shader" uid="uid://upgu5h4jlibh" path="res://color_sweep/colour_sweep.gdshader" id="2_hfxc4"]
+
+[sub_resource type="ShaderMaterial" id="ShaderMaterial_lquwl"]
+shader = ExtResource("2_hfxc4")
+shader_parameter/log2_min = -18.0
+shader_parameter/log2_max = 5.0
+shader_parameter/clip_to_max = false
+shader_parameter/max_value = 10.0
+
+[sub_resource type="QuadMesh" id="QuadMesh_7mycd"]
+
+[node name="ColorSweep" type="Control" unique_id=784950953]
+layout_mode = 3
+anchors_preset = 0
+script = ExtResource("1_3qbqk")
+
+[node name="ColourSweepMesh" type="MeshInstance2D" parent="." unique_id=852978860]
+unique_name_in_owner = true
+material = SubResource("ShaderMaterial_lquwl")
+position = Vector2(414.00003, 303)
+scale = Vector2(822.00006, -528.00006)
+mesh = SubResource("QuadMesh_7mycd")
+
+[node name="Tooltip" type="Control" parent="." unique_id=1015235051]
+anchors_preset = 0
+offset_left = 3.0
+offset_top = 39.0
+offset_right = 825.0
+offset_bottom = 567.0
+tooltip_text = "The upper tick mark indicates
+output_max_linear_value.
+
+The other tick marks are multiples
+of 0.01, 0.1, 1.0, 10.0, etc. with
+the rightmost white tick mark
+indicating 0.1 and the leftmost
+black tick mark indicating 0.2."
+
+[node name="HBoxContainer" type="HBoxContainer" parent="." unique_id=832456838]
+layout_mode = 0
+offset_top = 2.0
+offset_right = 828.0
+offset_bottom = 42.0
+alignment = 1
+
+[node name="Label" type="Label" parent="HBoxContainer" unique_id=873923751]
+layout_mode = 2
+text = "Min"
+
+[node name="MinHSlider" type="HSlider" parent="HBoxContainer" unique_id=2106554318]
+unique_name_in_owner = true
+custom_minimum_size = Vector2(180, 0)
+layout_mode = 2
+size_flags_vertical = 4
+min_value = -25.0
+max_value = 10.0
+step = 0.05000000000291038
+value = -13.999999999359712
+
+[node name="Label2" type="Label" parent="HBoxContainer" unique_id=473575971]
+layout_mode = 2
+text = "Max"
+
+[node name="MaxHSlider" type="HSlider" parent="HBoxContainer" unique_id=1145534836]
+unique_name_in_owner = true
+custom_minimum_size = Vector2(180, 0)
+layout_mode = 2
+size_flags_vertical = 4
+min_value = -25.0
+max_value = 10.0
+step = 0.05000000000291038
+value = 5.0000000017462405
+
+[node name="SweepMinLabel" type="Label" parent="." unique_id=648280970]
+unique_name_in_owner = true
+layout_mode = 0
+offset_left = 4.0
+offset_top = 10.0
+offset_right = 301.0
+offset_bottom = 33.0
+text = "0.000 (0.01 nits)"
+
+[node name="SweepMaxLabel" type="Label" parent="." unique_id=177120907]
+unique_name_in_owner = true
+layout_mode = 0
+offset_left = 499.0
+offset_top = 10.0
+offset_right = 823.0
+offset_bottom = 33.0
+text = "32.00 (13824.00 nits)"
+horizontal_alignment = 2
+
+[connection signal="value_changed" from="HBoxContainer/MinHSlider" to="." method="_on_min_h_slider_value_changed"]
+[connection signal="value_changed" from="HBoxContainer/MaxHSlider" to="." method="_on_max_h_slider_value_changed"]

hdr_output/color_sweep/colour_sweep.gd

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+extends Control
+
+var clip_to_max_lum: bool = false
+
+
+func _process(_delta: float) -> void:
+	var window: Window = get_window()
+	var window_id = get_window().get_window_id()
+	var sm: ShaderMaterial = %ColourSweepMesh.material as ShaderMaterial
+	sm.set_shader_parameter("max_value", window.get_output_max_linear_value());
+	%SweepMinLabel.text = "%0.3f (%0.2f nits)" % [pow(2, %MinHSlider.value), pow(2, %MinHSlider.value) * DisplayServer.window_get_hdr_output_current_reference_luminance(window_id)]
+	%SweepMaxLabel.text = "%0.2f (%0.2f nits)" % [pow(2, %MaxHSlider.value), pow(2, %MaxHSlider.value) * DisplayServer.window_get_hdr_output_current_reference_luminance(window_id)]
+
+
+func _on_min_h_slider_value_changed(value: float) -> void:
+	%MaxHSlider.min_value = value;
+	var sm: ShaderMaterial = %ColourSweepMesh.material as ShaderMaterial
+	sm.set_shader_parameter("log2_min", value)
+
+
+func _on_max_h_slider_value_changed(value: float) -> void:
+	%MinHSlider.max_value = value;
+	var sm: ShaderMaterial = %ColourSweepMesh.material as ShaderMaterial
+	sm.set_shader_parameter("log2_max", value)

hdr_output/color_sweep/colour_sweep.gd.uid

@@ -0,0 +1 @@
+uid://cqjmg63jbxlns

hdr_output/color_sweep/colour_sweep.gdshader

@@ -0,0 +1,106 @@
+shader_type canvas_item;
+render_mode unshaded;
+
+uniform float log2_min = -18.0;
+uniform float log2_max = 5.0;
+uniform bool clip_to_max = false;
+uniform float max_value = 10;
+
+void fragment() {
+	vec3 color;
+	float top_bar = 0.05;
+	float log2_value = UV.x * (log2_max - log2_min) + log2_min;
+	float scale = pow(2.0, log2_value);
+
+	if (UV.y >= top_bar)
+	{
+		float padding = 0.005;
+		float y = (UV.y - top_bar - padding) / (1.0 - top_bar - padding * 2.0);
+		y = clamp(y, 0.0, 1.0);
+		float segments = 1.0 / 6.0;
+		vec3 col = vec3(0);
+		if (y < segments)
+		{
+			col.r = 1.0;
+			col.g = y / segments;
+			col.b = 0.0;
+		}
+		else if (y < segments * 2.0)
+		{
+			col.r = (y - segments * 2.0) / -segments;
+			col.g = 1.0;
+			col.b = 0.0;
+		}
+		else if (y < segments * 3.0)
+		{
+			col.r = 0.0;
+			col.g = 1.0;
+			col.b = (y - segments * 2.0) / segments;
+		}
+		else if (y < segments * 4.0)
+		{
+			col.r = 0.0;
+			col.g = (y - segments * 4.0) / -segments;
+			col.b = 1.0;
+		}
+		else if (y < segments * 5.0)
+		{
+			col.r = (y - segments * 4.0) / segments;
+			col.g = 0.0;
+			col.b = 1.0;
+		}
+		else
+		{
+			col.r = 1.0;
+			col.g = 0.0;
+			col.b = (y - segments * 6.0) / -segments;
+		}
+
+		color = col * scale;
+	}
+	else
+	{
+		color = vec3(1.0) * scale;
+
+		if (UV.y < 0.01) {
+			// Max  value mark:
+			float max_log2 = log2(max_value);
+			float scale_log2 = log2(scale);
+			float mark_size = 0.03;
+			if (scale_log2 > max_log2 - mark_size && scale_log2 < max_log2 + mark_size) {
+				color = vec3(0);
+			}
+		} else if (UV.y > 0.03) {
+			// Log scale marks:
+			float tick_col = scale > 0.184 ? 0.0 : 1.0;
+			while (scale >= 1.0) {
+				scale /= 10.0;
+			}
+			while (scale < 0.1) {
+				scale *= 10.0;
+			}
+			float tick_threshold = scale * 0.02;
+			if ((scale > 1.0 - tick_threshold && scale < 1.0 + tick_threshold)
+				|| (scale > 0.0 - tick_threshold && scale < 0.0 + tick_threshold)
+				|| (scale > 0.1 - tick_threshold && scale < 0.1 + tick_threshold)) {
+				color = vec3(tick_col);
+			} else if (UV.y > 0.04
+				&& ((scale > 0.9 - tick_threshold && scale < 0.9 + tick_threshold)
+				|| (scale > 0.8 - tick_threshold && scale < 0.8 + tick_threshold)
+				|| (scale > 0.7 - tick_threshold && scale < 0.7 + tick_threshold)
+				|| (scale > 0.6 - tick_threshold && scale < 0.6 + tick_threshold)
+				|| (scale > 0.5 - tick_threshold && scale < 0.5 + tick_threshold)
+				|| (scale > 0.4 - tick_threshold && scale < 0.4 + tick_threshold)
+				|| (scale > 0.3 - tick_threshold && scale < 0.3 + tick_threshold)
+				|| (scale > 0.2 - tick_threshold && scale < 0.2 + tick_threshold))) {
+				color = vec3(tick_col);
+			}
+		}
+	}
+
+	if (clip_to_max) {
+		color = min(color, max_value);
+	}
+
+	COLOR = vec4(color.rgb, 1.0);
+}

hdr_output/color_sweep/colour_sweep.gdshader.uid

@@ -0,0 +1 @@
+uid://upgu5h4jlibh

hdr_output/environment/3d_environment.tscn

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+[gd_scene format=3 uid="uid://c0wukesav63su"]
+
+[ext_resource type="PackedScene" uid="uid://cyg6jtuudogcg" path="res://environment/gpu_particles_fire.tscn" id="1_oevuw"]
+
+[sub_resource type="ProceduralSkyMaterial" id="ProceduralSkyMaterial_7l7or"]
+sky_top_color = Color(0.34199998, 0.5161667, 0.76, 1)
+
+[sub_resource type="Sky" id="Sky_oevuw"]
+sky_material = SubResource("ProceduralSkyMaterial_7l7or")
+
+[sub_resource type="Environment" id="Environment_dg77c"]
+background_mode = 2
+sky = SubResource("Sky_oevuw")
+tonemap_mode = 4
+tonemap_agx_contrast = 1.32
+
+[node name="Node3D" type="Node3D" unique_id=229028905]
+
+[node name="WorldEnvironment" type="WorldEnvironment" parent="." unique_id=522993847]
+environment = SubResource("Environment_dg77c")
+
+[node name="Camera3D" type="Camera3D" parent="." unique_id=1229274230]
+transform = Transform3D(1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 2.0156713)
+
+[node name="DirectionalLight3D" type="DirectionalLight3D" parent="." unique_id=1268142717]
+
+[node name="GPUParticlesFire" parent="." unique_id=1592479161 instance=ExtResource("1_oevuw")]
+transform = Transform3D(1, 0, 0, 0, 1, 0, 0, 0, 1, 0, -0.7439877, 0)

hdr_output/environment/fire.tscn

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+[gd_scene format=3 uid="uid://bcif16iayg5dj"]
+
+[ext_resource type="Texture2D" uid="uid://dkl7yvfg3ivr3" path="res://fire_particle.png" id="1_2pqqt"]
+
+[sub_resource type="CanvasItemMaterial" id="1"]
+blend_mode = 1
+
+[sub_resource type="Curve" id="2"]
+_limits = [-360.0, 360.0, 0.0, 1.0]
+_data = [Vector2(0, 1), 0.0, 0.0, 0, 0, Vector2(1, 85.0781), 0.0, 0.0, 0, 0]
+point_count = 2
+
+[sub_resource type="CurveTexture" id="3"]
+curve = SubResource("2")
+
+[sub_resource type="Gradient" id="Gradient_wdtkk"]
+offsets = PackedFloat32Array(0, 0.142857, 0.506494, 0.961039)
+colors = PackedColorArray(0, 0, 0.803922, 1, 0.858824, 0.180392, 0.0470588, 1, 0.788235, 0.294118, 0, 1, 0, 0, 0, 0)
+
+[sub_resource type="GradientTexture1D" id="GradientTexture1D_fv41j"]
+gradient = SubResource("Gradient_wdtkk")
+
+[sub_resource type="Curve" id="4"]
+_data = [Vector2(0, 0), 0.0, 0.0, 0, 0, Vector2(0.11, 1), 0.0, 0.0, 0, 0, Vector2(1, 0), 0.0, 0.0, 0, 0]
+point_count = 3
+
+[sub_resource type="CurveTexture" id="5"]
+curve = SubResource("4")
+
+[sub_resource type="ParticleProcessMaterial" id="6"]
+emission_shape = 1
+emission_sphere_radius = 8.0
+angular_velocity_curve = SubResource("3")
+gravity = Vector3(0, -250, 0)
+scale_curve = SubResource("5")
+color_ramp = SubResource("GradientTexture1D_fv41j")
+
+[node name="Fire" type="GPUParticles2D" unique_id=1051806849]
+texture_filter = 4
+material = SubResource("1")
+amount = 32
+texture = ExtResource("1_2pqqt")
+preprocess = 1.0
+process_material = SubResource("6")

hdr_output/environment/fire_particle.png.import

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+[remap]
+
+importer="texture"
+type="CompressedTexture2D"
+uid="uid://dkl7yvfg3ivr3"
+path="res://.godot/imported/fire_particle.png-2d5c46863bbeaf227772f709dff146aa.ctex"
+metadata={
+"vram_texture": false
+}
+
+[deps]
+
+source_file="res://environment/fire_particle.png"
+dest_files=["res://.godot/imported/fire_particle.png-2d5c46863bbeaf227772f709dff146aa.ctex"]
+
+[params]
+
+compress/mode=0
+compress/high_quality=false
+compress/lossy_quality=0.7
+compress/uastc_level=0
+compress/rdo_quality_loss=0.0
+compress/hdr_compression=1
+compress/normal_map=0
+compress/channel_pack=0
+mipmaps/generate=true
+mipmaps/limit=-1
+roughness/mode=0
+roughness/src_normal=""
+process/channel_remap/red=0
+process/channel_remap/green=1
+process/channel_remap/blue=2
+process/channel_remap/alpha=3
+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