Improve background

main.tscn

@@ -1,4 +1,4 @@
-[gd_scene load_steps=18 format=3 uid="uid://cdaf4bh0jaa45"]
+[gd_scene load_steps=19 format=3 uid="uid://cdaf4bh0jaa45"]
 
 [ext_resource type="Script" path="res://scripts/game_logic.gd" id="1_uj8ti"]
 [ext_resource type="Script" path="res://scripts/player.gd" id="2_plgh6"]
@@ -7,9 +7,10 @@
 [ext_resource type="Script" path="res://scripts/player_local.gd" id="4_7rlmh"]
 [ext_resource type="Texture2D" uid="uid://dx1wjviioa8u5" path="res://icons/chip.svg" id="4_pgo63"]
 [ext_resource type="Script" path="res://scripts/ui/planets_ui.gd" id="7_khbdl"]
-[ext_resource type="PackedScene" uid="uid://dtlatmtuggp6x" path="res://scenes/background_nebula/background_nebula.tscn" id="7_sv4lv"]
+[ext_resource type="PackedScene" uid="uid://dtlatmtuggp6x" path="res://scenes/backgrounds/nebula.tscn" id="7_sv4lv"]
 [ext_resource type="Script" path="res://scripts/player_ai.gd" id="7_v73fw"]
 [ext_resource type="Script" path="res://scripts/planet.gd" id="8_ve3b1"]
+[ext_resource type="PackedScene" uid="uid://b0ec8jbenscpp" path="res://scenes/backgrounds/stars.tscn" id="9_lum1l"]
 
 [sub_resource type="Resource" id="Resource_mxp7y"]
 script = ExtResource("2_plgh6")
@@ -57,7 +58,9 @@ planets_ui = NodePath("../PlanetsUI")
 players = Array[ExtResource("2_plgh6")]([SubResource("Resource_mxp7y"), SubResource("Resource_1dtpf"), SubResource("Resource_7wtc7")])
 planets = Array[ExtResource("8_ve3b1")]([SubResource("Resource_50eg2"), SubResource("Resource_2525o"), SubResource("Resource_irtww"), SubResource("Resource_wdycy")])
 
-[node name="BackgroundNebula" parent="." instance=ExtResource("7_sv4lv")]
+[node name="Stars" parent="." instance=ExtResource("9_lum1l")]
+
+[node name="Nebula" parent="." instance=ExtResource("7_sv4lv")]
 
 [node name="Planets" type="Node2D" parent="."]
 

scenes/background_nebula/background_nebula.gdshader

@@ -1,14 +0,0 @@
-shader_type canvas_item;
-
-uniform sampler2D noise: repeat_enable;
-
-float rand(vec2 co){
-    return fract(sin(dot(co, vec2(12.9898, 78.233))) * 43758.5453);
-}
-
-void fragment() {
-	vec3 nebula = vec3(texture(noise, FRAGCOORD.xy * .0005).r, texture(noise, FRAGCOORD.xy * .0005 + 0.1).r, texture(noise, FRAGCOORD.xy * .0005 + 0.2).r) * 0.05;
-	vec3 star = (rand(FRAGCOORD.xy * .01) < 0.1 && rand(FRAGCOORD.xy * .02) < .01) ? vec3(rand(FRAGCOORD.xy * .03)) : vec3(0.);
-
-	COLOR = vec4(nebula + star, 1.);
-}

scenes/backgrounds/background_nebula.gdshader

@@ -0,0 +1,11 @@
+shader_type canvas_item;
+
+uniform sampler2D noise: repeat_enable;
+
+void fragment() {
+	float r = texture(noise, FRAGCOORD.xy * .0005 + .0).r;
+	float g = texture(noise, FRAGCOORD.xy * .0005 + .1).r;
+	float b = texture(noise, FRAGCOORD.xy * .0005 + .2).r;
+	float a = texture(noise, FRAGCOORD.xy * .0002 + .3).r * .35;
+	COLOR = vec4(r, g, b, a);
+}

scenes/backgrounds/background_stars.gdshader

@@ -0,0 +1,76 @@
+shader_type canvas_item;
+
+// Max 1 star for each cell, star size cannot be bigger than cell size.
+const float CELL_SIZE = 8.;
+const float MIN_STAR_SIZE = 1.;
+const float MAX_STAR_SIZE = 6.;
+const float START_DENSITY = .15; // Between 0 and 1.
+
+const float MIN_STAR_BRIGHTNESS = .10;
+const float MAX_STAR_BRIGHTNESS = 1.;
+
+const bool ALIGN_TO_PIXEL = true;
+
+const float INV_CELL_SIZE = 1. / CELL_SIZE;
+const float INV_MIN_STAR_SIZE = 1. / MIN_STAR_SIZE;
+const float INV_MAX_STAR_SIZE = 1. / MAX_STAR_SIZE;
+
+vec3 srgb_to_linear(vec3 col) {
+	return pow(col, vec3(2.2));
+}
+
+vec3 linear_to_srgb(vec3 col) {
+	return pow(col, vec3(1. / 2.2));
+}
+
+vec4 blend_additive(vec4 bg, vec4 fg) {
+	vec4 dst = vec4(srgb_to_linear(bg.rgb), bg.a);
+	vec4 src = vec4(srgb_to_linear(fg.rgb), fg.a);
+	// glBlendEquation(GL_FUNC_ADD)
+	// glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA)
+	vec4 res = src * src.a + dst * (1. - src.a);
+	return vec4(linear_to_srgb(res.rgb), res.a);
+}
+
+float rand(vec2 co){
+	return fract(sin(dot(co, vec2(12.9898, 78.233))) * 43758.5453);
+}
+
+void fragment() {
+	vec2 center_cell;
+	vec2 pos_inside_center_cell = modf(FRAGCOORD.xy * INV_CELL_SIZE, center_cell);
+
+	vec4 color = vec4(0., 0., 0., 0.);
+
+	for (float y = -1.; y < 1.5; y++) {
+		for (float x = -1.; x < 1.5; x++) {
+			vec2 cell = center_cell + vec2(x, y);
+			vec2 pos_inside_cell = pos_inside_center_cell - vec2(x, y);
+			
+			bool cell_has_star = rand(cell * .0101) < START_DENSITY;
+
+			if (!cell_has_star)
+				continue;
+
+			vec2 star_pos_inside_cell = vec2(rand(cell * .0112), rand(cell * .0123));
+			if (ALIGN_TO_PIXEL)
+				star_pos_inside_cell = floor(star_pos_inside_cell * CELL_SIZE) * INV_CELL_SIZE + INV_CELL_SIZE/2.; // Align to pixel.
+
+			vec2 relative_pos = pos_inside_cell - star_pos_inside_cell;
+			float dist_to_star = (cell_has_star ? 0. : 999.) + length(relative_pos);
+			float inv_star_size = mix(INV_MIN_STAR_SIZE, INV_MAX_STAR_SIZE, rand(cell * .0134));
+
+			float adjusted_shape = dist_to_star + min(abs(relative_pos.x), abs(relative_pos.y));
+			float pos_brightness = max(0., 1. - adjusted_shape * CELL_SIZE * inv_star_size);
+			float star_brightness = mix(MIN_STAR_BRIGHTNESS, MAX_STAR_BRIGHTNESS, rand(cell * 0.145));
+
+			vec2 rg = vec2(rand(cell * .0156), rand(cell * .0167));
+			vec3 star_color = vec3(rg, max(0., 1. - rg.r - rg.g));
+			star_color = mix(vec3(1.), star_color, .3);
+
+			color = blend_additive(color, vec4(star_color, pos_brightness * star_brightness));
+		}
+	}
+
+	COLOR = vec4(color.rgb, min(1., color.a));
+}

scenes/backgrounds/nebula.tscn

@@ -1,8 +1,9 @@
 [gd_scene load_steps=5 format=3 uid="uid://dtlatmtuggp6x"]
 
-[ext_resource type="Shader" path="res://scenes/background_nebula/background_nebula.gdshader" id="1_nqp0c"]
+[ext_resource type="Shader" path="res://scenes/backgrounds/background_nebula.gdshader" id="1_nqp0c"]
 
 [sub_resource type="FastNoiseLite" id="FastNoiseLite_8c2xm"]
+fractal_octaves = 4
 
 [sub_resource type="NoiseTexture2D" id="NoiseTexture2D_cukca"]
 width = 256

scenes/backgrounds/stars.tscn

@@ -0,0 +1,15 @@
+[gd_scene load_steps=3 format=3 uid="uid://b0ec8jbenscpp"]
+
+[ext_resource type="Shader" path="res://scenes/backgrounds/background_stars.gdshader" id="1_u4u73"]
+
+[sub_resource type="ShaderMaterial" id="ShaderMaterial_y72ex"]
+shader = ExtResource("1_u4u73")
+
+[node name="Stars" type="ColorRect"]
+material = SubResource("ShaderMaterial_y72ex")
+anchors_preset = 15
+anchor_right = 1.0
+anchor_bottom = 1.0
+grow_horizontal = 2
+grow_vertical = 2
+mouse_filter = 2