commit 9a3607b3de556b6d7f127c72be051b73318f8e83
Author: Leszek Koltunski <leszek@koltunski.pl>
Date:   Mon Nov 26 15:59:03 2018 +0000

    Fix the preprocess shader. This makes the 'Postprocess Tree' app look good again.

diff --git a/src/main/java/org/distorted/library/main/DistortedOutputSurface.java b/src/main/java/org/distorted/library/main/DistortedOutputSurface.java
index eab4103..9c276d2 100644
--- a/src/main/java/org/distorted/library/main/DistortedOutputSurface.java
+++ b/src/main/java/org/distorted/library/main/DistortedOutputSurface.java
@@ -399,7 +399,8 @@ public abstract class DistortedOutputSurface extends DistortedSurface implements
 ///////////////////////////////////////////////////////////////////////////////////////////////////
 // Render all children, one by one. If there are no postprocessing effects, just render to THIS.
 // Otherwise, render to a buffer and on each change of Postprocessing Bucket, apply the postprocessing
-// to a whole buffer (lastQueue.postprocess) and merge it (this.oitBuild).
+// to a whole buffer (lastQueue.postprocess) and merge it (this.oitBuild or blitWithDepth - depending
+// on the type of rendering)
 
   int renderChildren(long time, int numChildren, ArrayList<DistortedNode> children, int fbo, boolean oit)
     {
diff --git a/src/main/res/raw/preprocess_fragment_shader.glsl b/src/main/res/raw/preprocess_fragment_shader.glsl
index ceafbfa..6953a90 100644
--- a/src/main/res/raw/preprocess_fragment_shader.glsl
+++ b/src/main/res/raw/preprocess_fragment_shader.glsl
@@ -29,13 +29,5 @@ uniform sampler2D u_Texture;            // The input texture.
 void main()
   {
   vec4 color = texture(u_Texture,v_TexCoordinate);
-
-  if( color.a != 0.0 )
-    {
-    fragColor = u_Color;
-    }
-  else
-    {
-    discard;
-    }
+  fragColor  = vec4(u_Color.rgb, sign(color.a)*u_Color.a);
   }
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