From 5c4ff2b4caa835460a1cdaf0191f901109546568 Mon Sep 17 00:00:00 2001
From: kayomn <kayomn@kayomn.net>
Date: Tue, 10 Jan 2023 18:02:26 +0000
Subject: [PATCH] Improve terrain shading appearance

---
 editor.scn              |  4 ++--
 project.godot           |  4 ++--
 terrain_instance_3d.gd  | 49 +++++++----------------------------------
 terrain_shader.gdshader | 14 +++++++-----
 4 files changed, 20 insertions(+), 51 deletions(-)

diff --git a/editor.scn b/editor.scn
index b6355a0..0226e59 100644
--- a/editor.scn
+++ b/editor.scn
@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:4e5c5941e8562f7360298c2d3d03e21956cfa187424b2b1e01ba4bbba327f9ad
-size 5123
+oid sha256:4d2a991052e7d0bfb3cb39dbcc6b609a97c192e36c4aa916602edba30e8bcbef
+size 5163
diff --git a/project.godot b/project.godot
index 71b682f..a9234d7 100644
--- a/project.godot
+++ b/project.godot
@@ -93,6 +93,6 @@ editor_paint={
 
 [rendering]
 
-lights_and_shadows/directional_shadow/soft_shadow_filter_quality=5
+lights_and_shadows/directional_shadow/soft_shadow_filter_quality=3
 lights_and_shadows/directional_shadow/16_bits=false
-lights_and_shadows/positional_shadow/soft_shadow_filter_quality=5
+lights_and_shadows/positional_shadow/soft_shadow_filter_quality=3
diff --git a/terrain_instance_3d.gd b/terrain_instance_3d.gd
index c53cbc4..9680b6f 100644
--- a/terrain_instance_3d.gd
+++ b/terrain_instance_3d.gd
@@ -1,14 +1,9 @@
 @tool
 class_name TerrainInstance3D extends GeometryInstance3D
 
-var _mesh := ArrayMesh.new()
+var _mesh := PlaneMesh.new()
 
-var _material: ShaderMaterial = (func ():
-	var material := ShaderMaterial.new()
-
-	material.shader = preload("res://terrain_shader.gdshader")
-
-	return material).call()
+var _material := ShaderMaterial.new()
 
 ##
 ##
@@ -19,47 +14,16 @@ var size: Vector2i = Vector2i.ZERO:
 		return size
 
 	set(value):
-		self._mesh.clear_surfaces()
-
 		var width := value.x
 		var height := value.y
 
 		if (width != 0) and (height != 0):
 			if (width != size.x) or (height != size.y):
-				var surface_tool := SurfaceTool.new()
-
-				surface_tool.begin(Mesh.PRIMITIVE_TRIANGLES)
-
-				var center_x := width / 2.0
-				var center_y := height / 2.0
-
-				for y in height + 1:
-					for x in width + 1:
-						surface_tool.set_uv(Vector2(x / float(width), y / float(height)))
-						surface_tool.set_color(Color(0.0, 0.0, 0.0, 0.0))
-						surface_tool.set_normal(Vector3.UP)
-						surface_tool.add_vertex(Vector3(x - center_x, 0.0, y - center_y))
-
-				var vert := 0
-
-				for y in height:
-					for x in width:
-						surface_tool.add_index(vert + width + 2)
-						surface_tool.add_index(vert + width + 1)
-						surface_tool.add_index(vert + 1)
-						surface_tool.add_index(vert + 1)
-						surface_tool.add_index(vert + width + 1)
-						surface_tool.add_index(vert + 0)
-
-						vert += 1
-
-					vert += 1
-
-				RenderingServer.instance_set_base(self.get_instance(),
-					surface_tool.commit(self._mesh).get_rid())
+				self._mesh.subdivide_width = width
+				self._mesh.subdivide_depth = height
+				self._mesh.size = value
 
 				self._material.set_shader_parameter("SIZE", Vector2(value))
-				self._mesh.surface_set_material(0, self._material)
 
 		size = value
 
@@ -194,4 +158,7 @@ var max_height := 100.0:
 		max_height = max(value, 0.0)
 
 func _init() -> void:
+	self._material.shader = preload("res://terrain_shader.gdshader")
+
+	self._mesh.surface_set_material(0, self._material)
 	RenderingServer.instance_set_base(self.get_instance(), self._mesh)
diff --git a/terrain_shader.gdshader b/terrain_shader.gdshader
index 2fca663..dfac4b8 100644
--- a/terrain_shader.gdshader
+++ b/terrain_shader.gdshader
@@ -46,11 +46,13 @@ float height(vec2 uv) {
 void vertex() {
 	VERTEX.y = height(UV);
 
-	vec2 texel = vec2(1.0, 1.0) / SIZE;
-	float left = height(vec2(UV.x - texel.x, UV.y));
-	float right = height(vec2(UV.x + texel.x, UV.y));
-	float forward = height(vec2(UV.x, UV.y + texel.y));
-	float backward = height(vec2(UV.x, UV.y - texel.y));
+	vec2 texel_size = UV / SIZE;
 
-	NORMAL = normalize(vec3(left - right, 2.0, forward - forward));
+	vec4 h = vec4(
+		height(UV + (texel_size * vec2(0, -1))),
+		height(UV + (texel_size * vec2(-1, 0))),
+		height(UV + (texel_size * vec2( 1, 0))),
+		height(UV + (texel_size * vec2( 0, 1))));
+
+	NORMAL = normalize(vec3(h.y - h.z, 2.0, h.x - h.w));
 }