Add trail to bloom

shader/fullscreen/alphaHalve.frag

@@ -0,0 +1,3 @@
+#version 430 core
+out vec4 fColor;
+void main () { fColor = vec4(0,0,0,0.5);}

shader/fullscreen/alphaHalve.vert

@@ -0,0 +1,4 @@
+#version 430 core
+layout (location = 0) in vec2 position;
+void main()
+{ gl_Position = vec4 (position, 0 , 1);}