From e122b34858b40eaf70bb9888bc85b14e450fa38d Mon Sep 17 00:00:00 2001
From: Robert Osfield <robert@openscenegraph.com>
Date: Mon, 2 Aug 2004 07:25:28 +0000
Subject: [PATCH] From Tom Jolly.  a couple of small changes to osgParticle.

"The first is with
Particle.cpp.  I made a change so that when the lifetime is 0 (lasts
forever) the sizeRange, colorRange, and alphaRange are used to create
a random size, color, and alpha."

"The second change is with range and SectorPlacer.  The distribution of
particles across the sector was not uniform.  I added get_random_sqrtf()
function where it is used in SectorPlacer::Place().  This seems to make
the distribution uniform (at least when minimum radius is 0)."
---
 include/osgParticle/SectorPlacer |  2 +-
 include/osgParticle/range        |  6 ++++++
 src/osgParticle/Particle.cpp     | 14 +++++++++++---
 3 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/include/osgParticle/SectorPlacer b/include/osgParticle/SectorPlacer
index 9d31357cd..5e79516f2 100644
--- a/include/osgParticle/SectorPlacer
+++ b/include/osgParticle/SectorPlacer
@@ -116,7 +116,7 @@ namespace osgParticle
 
     inline void SectorPlacer::place(Particle *P) const
     {
-        float rad = rad_range_.get_random();
+        float rad = rad_range_.get_random_sqrtf();
         float phi = phi_range_.get_random();
         
         osg::Vec3 pos(
diff --git a/include/osgParticle/range b/include/osgParticle/range
index 03f5c0255..f48087afb 100644
--- a/include/osgParticle/range
+++ b/include/osgParticle/range
@@ -64,6 +64,12 @@ namespace osgParticle
             return minimum + (maximum - minimum) * rand() / RAND_MAX;
         }
 
+        /// Get a random square root value between min and max.
+        T_ get_random_sqrtf() const
+        {
+            return minimum + (maximum - minimum) * sqrtf( static_cast<float>(rand()) / static_cast<float>(RAND_MAX) );
+        }
+
     };
 
     /// Range of floats.
diff --git a/src/osgParticle/Particle.cpp b/src/osgParticle/Particle.cpp
index 06307aa88..3ad314505 100644
--- a/src/osgParticle/Particle.cpp
+++ b/src/osgParticle/Particle.cpp
@@ -86,9 +86,17 @@ bool osgParticle::Particle::update(double dt)
 	}
 	
     // compute the current values for size, alpha and color.
-    current_size_ = si_.get()->interpolate(x, sr_);
-    current_alpha_ = ai_.get()->interpolate(x, ar_);
-    current_color_ = ci_.get()->interpolate(x, cr_);
+    if (lifetime_ <= 0) {
+       if (dt == t0_) {
+          current_size_ = sr_.get_random();
+          current_alpha_ = ar_.get_random();
+          current_color_ = cr_.get_random();
+       }
+    } else {
+       current_size_ = si_.get()->interpolate(x, sr_);
+       current_alpha_ = ai_.get()->interpolate(x, ar_);
+       current_color_ = ci_.get()->interpolate(x, cr_);
+    }
 
     // update position
     prev_pos_ = position_;