From f501ffe2862fd8b4c5793542190e8e0a0d8de667 Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Sat, 9 Oct 2021 20:58:14 +0300
Subject: [PATCH] Add attenuation calculations and related export code for
 point lights

---
 blender/io_mspgl/export_light.py | 1 +
 shaderlib/common.glsl            | 3 ++-
 shaderlib/msp_interface.glsl     | 1 +
 source/materials/lighting.cpp    | 3 ++-
 source/materials/pointlight.cpp  | 1 +
 source/materials/pointlight.h    | 2 +-
 6 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/blender/io_mspgl/export_light.py b/blender/io_mspgl/export_light.py
index 2fc8c8dd..7ccb9663 100644
--- a/blender/io_mspgl/export_light.py
+++ b/blender/io_mspgl/export_light.py
@@ -16,6 +16,7 @@ class LightExporter:
 			light_res.statements.append(Statement("type", Token("point")))
 			pos = obj.matrix_world@mathutils.Vector((0.0, 0.0, 0.0, 1.0))
 			light_res.statements.append(Statement("position", *obj.matrix_world.col[3][0:3]))
+			light_res.statements.append(Statement("attenuation", 1.0, 0.0, 1.0))
 		else:
 			raise Exception("Can't export light {} of unknown type {}".format(light.name, light.type))
 
diff --git a/shaderlib/common.glsl b/shaderlib/common.glsl
index 4d6112d9..33fefe88 100644
--- a/shaderlib/common.glsl
+++ b/shaderlib/common.glsl
@@ -90,7 +90,8 @@ virtual IncomingLight get_incoming_light(int index, vec3 world_pos)
 	vec4 light_pos = light_sources[index].position;
 	vec3 rel_pos = light_pos.xyz-world_pos*light_pos.w;
 	float d = length(rel_pos);
-	return IncomingLight(rel_pos/d, light_sources[index].color);
+	float attenuation = 1.0/dot(vec3(1.0, d, d*d), light_sources[index].attenuation);
+	return IncomingLight(rel_pos/d, light_sources[index].color*attenuation);
 }
 
 virtual vec3 get_environment_sample(vec3 direction, float roughness)
diff --git a/shaderlib/msp_interface.glsl b/shaderlib/msp_interface.glsl
index d8de5d24..b0f8a410 100644
--- a/shaderlib/msp_interface.glsl
+++ b/shaderlib/msp_interface.glsl
@@ -3,6 +3,7 @@ struct LightSourceParameters
 	vec4 position;
 	vec3 color;
 	int type;
+	vec3 attenuation;
 };
 
 struct ClipPlane
diff --git a/source/materials/lighting.cpp b/source/materials/lighting.cpp
index f6bb39ff..6957126b 100644
--- a/source/materials/lighting.cpp
+++ b/source/materials/lighting.cpp
@@ -18,12 +18,13 @@ Lighting::Lighting()
 	set_fog_color(Color(0.0f, 0.0f, 0.0f, 0.0f));
 	set_fog_density(0.0f);
 
-	for(unsigned i=0; i<8; ++i)
+	for(unsigned i=0; i<7; ++i)
 	{
 		string base = format("light_sources[%d]", i);
 		shdata.uniform(base+".position", Vector4(0, 0, 1, 0));
 		shdata.uniform(base+".color", 0.0f, 0.0f, 0.0f);
 		shdata.uniform(base+".type", 0);
+		shdata.uniform(base+".attenuation", 1.0f, 0.0f, 0.0f);
 	}
 }
 
diff --git a/source/materials/pointlight.cpp b/source/materials/pointlight.cpp
index 9a726a2a..3147eaa3 100644
--- a/source/materials/pointlight.cpp
+++ b/source/materials/pointlight.cpp
@@ -39,6 +39,7 @@ void PointLight::update_shader_data(ProgramData &shdata, const string &base) con
 	shdata.uniform(base+".type", 2);
 	shdata.uniform(base+".position", position.x, position.y, position.z, 1.0f);
 	shdata.uniform(base+".color", color.r, color.g, color.b);
+	shdata.uniform3(base+".attenuation", attenuation);
 }
 
 
diff --git a/source/materials/pointlight.h b/source/materials/pointlight.h
index 1c373504..ed9789c7 100644
--- a/source/materials/pointlight.h
+++ b/source/materials/pointlight.h
@@ -31,7 +31,7 @@ public:
 
 private:
 	Vector3 position = { 0.0f, 0.0f, 0.0f };
-	float attenuation[3] = { 1.0f, 0.0f, 0.1f };
+	float attenuation[3] = { 1.0f, 0.0f, 1.0f };
 
 	void update_matrix();
 
-- 
2.43.0