new terrain plugin

demo/assets/materials/M_crystal_blue.tres

@@ -0,0 +1,25 @@
+[gd_resource type="StandardMaterial3D" load_steps=2 format=3 uid="uid://fkhkir6t1hml"]
+
+[ext_resource type="Texture2D" uid="uid://c307hdmos4gtm" path="res://demo/assets/textures/rock023_nrm_rgh.png" id="2_3is54"]
+
+[resource]
+transparency = 1
+vertex_color_use_as_albedo = true
+albedo_color = Color(0.4, 1, 1, 0.647059)
+metallic_specular = 1.0
+roughness = 0.2
+roughness_texture = ExtResource("2_3is54")
+roughness_texture_channel = 3
+emission_enabled = true
+emission = Color(0, 0.145098, 0.776471, 1)
+emission_energy_multiplier = 1.4
+normal_enabled = true
+normal_scale = 0.4
+normal_texture = ExtResource("2_3is54")
+rim_enabled = true
+rim = 0.25
+clearcoat_roughness = 0.0
+ao_light_affect = 1.0
+ao_texture_channel = 3
+refraction_enabled = true
+refraction_scale = -0.1