From 1d1521456527343d7cf12964b486cc724514cdb5 Mon Sep 17 00:00:00 2001
From: Digvijaysinh Gohil <zdigv96@gmail.com>
Date: Tue, 26 Mar 2024 10:59:07 +0530
Subject: [PATCH] Ray march node added

---
 addons/ShaderLib/RayMarching/RayMarch.gd      | 83 +++++++++++++++++++
 .../RayMarching/RayMarch.gdshaderinc          | 14 ++++
 documentation/Documentation.md                |  4 +
 documentation/Nodes/RayMarching/RayMarch.md   | 19 +++++
 4 files changed, 120 insertions(+)
 create mode 100644 addons/ShaderLib/RayMarching/RayMarch.gd
 create mode 100644 addons/ShaderLib/RayMarching/RayMarch.gdshaderinc
 create mode 100644 documentation/Nodes/RayMarching/RayMarch.md

diff --git a/addons/ShaderLib/RayMarching/RayMarch.gd b/addons/ShaderLib/RayMarching/RayMarch.gd
new file mode 100644
index 0000000..7fea588
--- /dev/null
+++ b/addons/ShaderLib/RayMarching/RayMarch.gd
@@ -0,0 +1,83 @@
+@tool
+class_name VisualShaderNodeRayMarch extends VisualShaderNodeCustom
+
+func _get_name() -> String:
+	return "RayMarch"
+
+func _get_category() -> String:
+	return "RayMarching"
+
+func _get_description() -> String:
+	return "A simple ray marcher."
+
+func _get_return_icon_type() -> PortType:
+	return PORT_TYPE_SCALAR
+
+func _get_input_port_count() -> int:
+	return 6
+
+func _get_input_port_name(port: int) -> String:
+	match port:
+		0:
+			return "signed distance"
+		1:
+			return "ray origin"
+		2:
+			return "ray direction"
+		3:
+			return "max steps"
+		4:
+			return "max distance"
+		_:
+			return "distance threshold"
+
+func _get_input_port_type(port: int) -> PortType:
+	match port:
+		1, 2:
+			return PORT_TYPE_VECTOR_3D
+		3:
+			return PORT_TYPE_SCALAR_INT
+		_:
+			return PORT_TYPE_SCALAR
+
+func _get_input_port_default_value(port: int) -> Variant:
+	match port:
+		1:
+			return Vector3(0, 0, -1)
+		2:
+			return Vector3(0 ,0 ,0)
+		3:
+			return 15
+		4:
+			return 15.0
+		5:
+			return 1e-2
+		_:
+			return null
+
+func _get_output_port_count() -> int:
+	return 1
+
+func _get_output_port_name(port: int) -> String:
+	return "distance"
+
+func _get_output_port_type(port: int) -> PortType:
+	return PORT_TYPE_SCALAR
+
+func _get_global_code(mode: Shader.Mode) -> String:
+	var code: String = preload("RayMarch.gdshaderinc").code
+	return code
+
+func _get_code(input_vars: Array[String], output_vars: Array[String], mode: Shader.Mode, type: VisualShader.Type) -> String:
+	var signed_distance: String = "0.0"
+
+	if input_vars[0]:
+		signed_distance = input_vars[0]
+
+	var ray_origin: String = input_vars[1]
+	var ray_direction: String = input_vars[2]
+	var max_steps: String = input_vars[3]
+	var max_dist: String = input_vars[4]
+	var dist_threshold: String = input_vars[5]
+
+	return output_vars[0] + " = ray_march(%s, %s, %s, %s, %s, %s);" % [ray_origin, ray_direction, max_steps, max_dist, dist_threshold, signed_distance]
diff --git a/addons/ShaderLib/RayMarching/RayMarch.gdshaderinc b/addons/ShaderLib/RayMarching/RayMarch.gdshaderinc
new file mode 100644
index 0000000..c24a18f
--- /dev/null
+++ b/addons/ShaderLib/RayMarching/RayMarch.gdshaderinc
@@ -0,0 +1,14 @@
+float ray_march(vec3 ray_origin, vec3 ray_dir, int max_steps, float max_dist, float dist_threshold, float signed_dist) {
+	ray_dir = normalize(ray_dir);
+	dist_threshold = abs(dist_threshold);
+	float dist_from_origin = 0.;
+	float dist_to_surface;
+	for(int i = 0; i < max_steps; i++) {
+		vec3 point = ray_origin + dist_from_origin * ray_dir;
+		dist_to_surface = signed_dist;
+		dist_from_origin += dist_to_surface;
+		if(dist_to_surface < dist_threshold || dist_to_surface > max_dist)
+			break;
+	}
+	return dist_from_origin;
+}
\ No newline at end of file
diff --git a/documentation/Documentation.md b/documentation/Documentation.md
index bcb8b18..2731592 100644
--- a/documentation/Documentation.md
+++ b/documentation/Documentation.md
@@ -72,6 +72,10 @@ For example if you want to rotate UV in your **_.gdshader_** file, you can use `
 <h4><a href="/documentation/Nodes/Procedural/Shapes/RoundedPolygon.md">&emsp;&emsp;Rounded Polygon node</a></h4>
 <h4><a href="/documentation/Nodes/Procedural/Shapes/RoundedRectangle.md">&emsp;&emsp;Rounded Rectangle node</a></h4>
 
+<h2>Ray marching nodes</h2>
+
+<h4><a href="/documentation/Nodes/RayMarching/RayMarch.md">&emsp;Ray March node</a></h4>
+
 <h2>UV nodes</h2>
 
 <h4><a href="/documentation/Nodes/UV/Flipbook.md">&emsp;Flipbook node</a></h4>
diff --git a/documentation/Nodes/RayMarching/RayMarch.md b/documentation/Nodes/RayMarching/RayMarch.md
new file mode 100644
index 0000000..9c713dc
--- /dev/null
+++ b/documentation/Nodes/RayMarching/RayMarch.md
@@ -0,0 +1,19 @@
+# Ray March node
+A simple ray marcher.
+<hr>
+
+**Inputs**
+|Name|Type|Binding|Description|
+|---|---|---|---|
+|signed distance|float|none|Signed distance calculated from Signed Distance Functions (SDFs)|
+|ray origin|vec3|none|Ray origin|
+|ray direction|vec3|none|Normalized ray direction|
+|max steps|int|none|Maximum number steps for ray marching|
+|max distance|float|none|Maximum distance to march along the <b><i>ray direction</i></b>|
+|distance threshold|float|none|Threshold to check against <b><i>signed distance</i></b> to determine the ray intersection point.|
+  
+**Outputs**
+|Name|Type|Binding|Description|
+|---|---|---|---|
+|distance|float|None|Output ray intersection distance|
+___
\ No newline at end of file