porting starlight shader to godot4

src/base-environments/youth_room/import/starlight-mesh.glb.import

@@ -34,6 +34,18 @@ _subresources={
 "use_external/enabled": true,
 "use_external/path": "res://base-environments/youth_room/import/materials/starlight_shader.material"
 }
+},
+"meshes": {
+"starlight-mesh_room001": {
+"generate/lightmap_uv": 0,
+"generate/lods": 0,
+"generate/shadow_meshes": 0,
+"lods/normal_merge_angle": 60.0,
+"lods/normal_split_angle": 25.0,
+"save_to_file/enabled": true,
+"save_to_file/make_streamable": "",
+"save_to_file/path": "res://base-environments/youth_room/shaders/starlight-mesh.res"
+}
 }
 }
 gltf/embedded_image_handling=1

src/base-environments/youth_room/shaders/starlight-textures.png.import

@@ -3,23 +3,24 @@
 importer="texture"
 type="CompressedTexture2D"
 uid="uid://bdyg065h8vcdi"
-path="res://.godot/imported/starlight-textures.png-4ddade130465fa71fbca6304c0a7a75a.ctex"
+path.bptc="res://.godot/imported/starlight-textures.png-4ddade130465fa71fbca6304c0a7a75a.bptc.ctex"
 metadata={
-"vram_texture": false
+"imported_formats": ["s3tc_bptc"],
+"vram_texture": true
 }
 
 [deps]
 
 source_file="res://base-environments/youth_room/shaders/starlight-textures.png"
-dest_files=["res://.godot/imported/starlight-textures.png-4ddade130465fa71fbca6304c0a7a75a.ctex"]
+dest_files=["res://.godot/imported/starlight-textures.png-4ddade130465fa71fbca6304c0a7a75a.bptc.ctex"]
 
 [params]
 
-compress/mode=3
+compress/mode=2
 compress/high_quality=true
 compress/lossy_quality=0.7
 compress/hdr_compression=1
-compress/normal_map=0
+compress/normal_map=1
 compress/channel_pack=0
 mipmaps/generate=true
 mipmaps/limit=-1

src/base-environments/youth_room/shaders/starlight_shader.gdshader

@@ -1,9 +1,37 @@
 shader_type spatial;
-render_mode unshaded;
+render_mode blend_add, specular_disabled;
 
+uniform float nebula_brightness = 4;
+uniform vec2 nebula_scale = vec2(1.5);
 uniform sampler2D starlight_noise;
 uniform sampler2D starlight_textures;
+uniform float rotation_speed = 0.05;
+uniform vec2 rotation_pivot = vec2(.8);
+uniform vec2 drift_compensation = vec2(0.1, -0.2);
+uniform float noise_strength = 0.2;
+
+// https://gist.github.com/ayamflow/c06bc0c8a64f985dd431bd0ac5b557cd
+vec2 rotateUV(vec2 uv, vec2 pivot, float rotation)
+{
+    return vec2(
+      cos(rotation) * (uv.x - pivot.x) + sin(rotation) * (uv.y - pivot.y) + pivot.x,
+      cos(rotation) * (uv.y - pivot.y) - sin(rotation) * (uv.x - pivot.x) + pivot.y
+    );
+}
+
+//clamp(, .0, 1.0
 
 void fragment() {
-	ALBEDO = vec3(.0, .0, texture(starlight_textures, UV + texture(starlight_noise, UV).xz).z);
+	ALBEDO = vec3(.0,
+                  texture(starlight_textures,UV).x * max(sin(TIME + 10.0 * texture(starlight_textures,UV).y), .0),
+                  texture(starlight_textures,
+                            clamp(
+                                UV / nebula_scale + drift_compensation + 1.0 *
+                                    texture(starlight_noise, rotateUV( 
+                                                                UV / nebula_scale + noise_strength * texture(starlight_noise, rotateUV(UV, -rotation_pivot, TIME*rotation_speed)).yx,
+                                                                rotation_pivot, TIME*rotation_speed)
+                                            ).xz,
+                                    .0, 1.0))
+                                .z * nebula_brightness);
+    SPECULAR = 0.0;
 }