* Proper aging for particles emitted in a frame

git-svn-id: https://jmonkeyengine.googlecode.com/svn/trunk@7958 75d07b2b-3a1a-0410-a2c5-0572b91ccdca

engine/src/core/com/jme3/effect/ParticleEmitter.java

@@ -90,7 +90,7 @@ public class ParticleEmitter extends Geometry {
     private boolean selectRandomImage;
     private boolean facingVelocity;
     private float particlesPerSec = 20;
-    private float emitCarry;
+    private float timeDifference = 0;
     private float lowLife = 3f;
     private float highLife = 7f;
     private Vector3f gravity = new Vector3f(0.0f, 0.1f, 0.0f);
@@ -206,8 +206,6 @@ public class ParticleEmitter extends Geometry {
 
         meshType = type;
 
-
-
         // Must create clone of shape/influencer so that a reference to a static is 
         // not maintained
         shape = shape.deepClone();
@@ -859,13 +857,13 @@ public class ParticleEmitter extends Geometry {
 //        assert !unusedIndices.contains(index);
 //        unusedIndices.add(index);
 //    }
-    private boolean emitParticle(Vector3f min, Vector3f max) {
+    private Particle emitParticle(Vector3f min, Vector3f max) {
 //        int idx = newIndex();
 //        if (idx == -1)
 //            return false;
         int idx = lastUsed + 1;
         if (idx >= particles.length) {
-            return false;
+            return null;
         }
 
         Particle p = particles[idx];
@@ -896,7 +894,7 @@ public class ParticleEmitter extends Geometry {
 
         ++lastUsed;
         firstUnUsed = idx + 1;
-        return true;
+        return p;
     }
 
     /**
@@ -924,7 +922,7 @@ public class ParticleEmitter extends Geometry {
             max.set(Vector3f.NEGATIVE_INFINITY);
         }
 
-        while (emitParticle(min, max));
+        while (emitParticle(min, max) != null);
 
         bbox.setMinMax(min, max);
         this.setBoundRefresh();
@@ -971,32 +969,7 @@ public class ParticleEmitter extends Geometry {
         particles[idx2] = p1;
     }
 
-    private void updateParticleState(float tpf) {
+    private void updateParticle(Particle p, float tpf, Vector3f min, Vector3f max){
-        // Force world transform to update
-        this.getWorldTransform();
-
-        TempVars vars = TempVars.get();
-
-
-        Vector3f min = vars.vect1.set(Vector3f.POSITIVE_INFINITY);
-        Vector3f max = vars.vect2.set(Vector3f.NEGATIVE_INFINITY);
-
-        for (int i = 0; i < particles.length; ++i) {
-            Particle p = particles[i];
-            if (p.life == 0) { // particle is dead
-//                assert i <= firstUnUsed;
-                continue;
-            }
-
-            p.life -= tpf;
-            if (p.life <= 0) {
-                this.freeParticle(i);
-                continue;
-            }
-
-            // position += velocity * tpf
-            //p.distToCam = -1;
-
         // applying gravity
         p.velocity.x -= gravity.x * tpf;
         p.velocity.y -= gravity.y * tpf;
@@ -1019,6 +992,31 @@ public class ParticleEmitter extends Geometry {
         if (!selectRandomImage) {
             p.imageIndex = (int) (b * imagesX * imagesY);
         }
+    }
+    
+    private void updateParticleState(float tpf) {
+        // Force world transform to update
+        this.getWorldTransform();
+
+        TempVars vars = TempVars.get();
+
+        Vector3f min = vars.vect1.set(Vector3f.POSITIVE_INFINITY);
+        Vector3f max = vars.vect2.set(Vector3f.NEGATIVE_INFINITY);
+
+        for (int i = 0; i < particles.length; ++i) {
+            Particle p = particles[i];
+            if (p.life == 0) { // particle is dead
+//                assert i <= firstUnUsed;
+                continue;
+            }
+
+            p.life -= tpf;
+            if (p.life <= 0) {
+                this.freeParticle(i);
+                continue;
+            }
+
+            updateParticle(p, tpf, min, max);
 
             if (firstUnUsed < i) {
                 this.swap(firstUnUsed, i);
@@ -1029,18 +1027,22 @@ public class ParticleEmitter extends Geometry {
             }
         }
         
-        float particlesToEmitF = particlesPerSec * tpf;
+        // Spawns particles within the tpf timeslot with proper age
-        int particlesToEmit = (int) particlesToEmitF;
+        float interval = 1f / particlesPerSec;
-        emitCarry += particlesToEmitF - particlesToEmit;
+        tpf += timeDifference;
-
+        while (tpf > interval){
-        while (emitCarry > 1f) {
+            tpf -= interval;
-            ++particlesToEmit;
+            Particle p = emitParticle(min, max);
-            emitCarry -= 1f;
+            if (p != null){
+                p.life -= tpf;
+                if (p.life <= 0){
+                    freeParticle(lastUsed);
+                }else{
+                    updateParticle(p, tpf, min, max);
+                }
             }
-
-        for (int i = 0; i < particlesToEmit; ++i) {
-            this.emitParticle(min, max);
         }
+        timeDifference = tpf;
 
         BoundingBox bbox = (BoundingBox) this.getMesh().getBound();
         bbox.setMinMax(min, max);