From c0e4fce3f0546b0e2d02cf104a50acc42c70b04c Mon Sep 17 00:00:00 2001
From: Faerbit <faerbit@gmail.com>
Date: Sun, 8 Mar 2015 01:53:00 +0100
Subject: [PATCH] Added flickering to the geometry shader.

---
 data/shader/flame.gsh | 53 +++++++++++++++++++++++++++++++------------
 1 file changed, 38 insertions(+), 15 deletions(-)

diff --git a/data/shader/flame.gsh b/data/shader/flame.gsh
index 0fda82a..61aa9af 100644
--- a/data/shader/flame.gsh
+++ b/data/shader/flame.gsh
@@ -12,37 +12,60 @@ in vec3 Color[];
 out vec3 fColor;
 
 const float PI = 3.1415926;
-const float transition_point = 1.178097;
-const float sin_p1  = 0.4;
-const float sin_p2  = 2;
-const float ex_p1   = 1.093;
-const float ex_p2   = 1.9996;
-const float begin   = 0;
-const float end     = 2.5;
+const float transition_point_1 = 1.178097;
+const float sin_p1_1  = 0.4;
+const float sin_p2_1  = 2;
+const float ex_p1_1   = 1.093;
+const float ex_p2_1   = 1.9996;
+const float begin_1   = 0;
+const float end_1     = 2.5;
+
+const float transition_point_2 = 1.570796;
+const float sin_p1_2  = 0.2;
+const float sin_p2_2  = 1.5;
+const float ex_p1_2   = 0.4;
+const float ex_p2_2   = 1.5;
+const float begin_2   = 0;
+const float end_2     = 3;
+
+float flickerFunction() {
+    return sin(time);
+}
 
 float radiusFunction(float x) {
-    if (x < transition_point) {
-        return sin_p1 * sin(sin_p2 * x);
+    float value_1 = 0.0;
+    float value_2 = 0.0;
+    if (x < transition_point_1) {
+        value_1 = sin_p1_1 * sin(sin_p2_1 * x);
     }
     else {
-        return exp(ex_p1 - ex_p2 * x);
+        value_1 = exp(ex_p1_1 - ex_p2_1 * x);
     }
+    if (x < transition_point_2) {
+        value_2 = sin_p1_2 * sin(sin_p2_2 * x);
+    }
+    else {
+        value_2 = exp(ex_p1_2 - ex_p2_2 * x);
+    }
+    return mix(value_1, value_2, flickerFunction());
 }
 
 void main() {
     fColor = Color[0];
 
     float resolution = 8.0;
-    float step = abs(end-begin)/resolution/2.0;
+    float this_begin = mix(begin_1, begin_2, flickerFunction());
+    float this_end = mix(end_1, end_2, flickerFunction());
+    float step = abs(this_end-this_begin)/resolution/2.0;
     float i = 0.0;
     float render_end = 0.0;
     if (bottom) {
-        i = begin;
-        render_end = (end-begin)/2.0+step;
+        i = this_begin;
+        render_end = (this_end-this_begin)/2.0+step;
     }
     else {
-        i = (end-begin)/2.0;
-        render_end = end;
+        i = (this_end-this_begin)/2.0;
+        render_end = this_end;
     }
     for (i; i<render_end; i+=step) {
         float downRadius    = radiusFunction(i);