From 518cf3be1504234eb0dc22906876e292b2186f57 Mon Sep 17 00:00:00 2001
From: Sam Gateau <sam@highfidelity.io>
Date: Fri, 21 Aug 2015 16:28:38 -0700
Subject: [PATCH] Improve the light attenuation formulae

---
 libraries/model/src/model/Light.cpp | 11 +++++++++--
 libraries/model/src/model/Light.h   |  2 ++
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/libraries/model/src/model/Light.cpp b/libraries/model/src/model/Light.cpp
index 525f68e640..823be727a4 100755
--- a/libraries/model/src/model/Light.cpp
+++ b/libraries/model/src/model/Light.cpp
@@ -58,10 +58,12 @@ const Vec3& Light::getDirection() const {
 
 void Light::setColor(const Color& color) {
     editSchema()._color = color;
+    updateLightRadius();
 }
 
 void Light::setIntensity(float intensity) {
     editSchema()._intensity = intensity;
+    updateLightRadius();
 }
 
 void Light::setAmbientIntensity(float intensity) {
@@ -72,9 +74,14 @@ void Light::setMaximumRadius(float radius) {
     if (radius <= 0.f) {
         radius = 1.0f;
     }
+    editSchema()._attenuation.w = radius;
+    updateLightRadius();
+}
+
+void Light::updateLightRadius() {
     float CutOffIntensityRatio = 0.05f;
-    float surfaceRadius = radius / (sqrtf(1.0f / CutOffIntensityRatio) - 1.0f);
-    editSchema()._attenuation = Vec4(surfaceRadius, 1.0f/surfaceRadius, CutOffIntensityRatio, radius);
+    float surfaceRadius = getMaximumRadius() / (sqrtf((getIntensity() * std::max(std::max(getColor().x, getColor().y), getColor().z)) / CutOffIntensityRatio) - 1.0f);
+    editSchema()._attenuation = Vec4(surfaceRadius, 1.0f/surfaceRadius, CutOffIntensityRatio, getMaximumRadius());
 }
 
 #include <math.h>
diff --git a/libraries/model/src/model/Light.h b/libraries/model/src/model/Light.h
index 1ed07a942c..3fbaba75bf 100755
--- a/libraries/model/src/model/Light.h
+++ b/libraries/model/src/model/Light.h
@@ -127,6 +127,8 @@ protected:
 
     const Schema& getSchema() const { return _schemaBuffer.get<Schema>(); }
     Schema& editSchema() { return _schemaBuffer.edit<Schema>(); }
+
+    void updateLightRadius();
 };
 typedef std::shared_ptr< Light > LightPointer;