Play around with alpha blending

shader/lighting/lineShadow.geom

@@ -4,8 +4,6 @@ layout(triangle_strip, max_vertices = 4) out;
 layout(std140, binding = 0) uniform TheMat { mat4 theMat; };
 layout(location=0) uniform vec3 lightPos;
 layout(location=1) uniform float radiusUniform;
-// vec4 shift (vec4 p) { return (vec4 (p.xyz +
-// (lumRad.a*normalize(p.xyz-lightPos)), 1));}
 float closestPointOnLineParam3 (vec3 a, vec3 b, vec3 p) {
   return dot(p - a,b-a) / dot(b-a,b-a);
 }
@@ -17,13 +15,10 @@ vec3 closestPointOnSeg3 (vec3 a,vec3 b, vec3 p) {
       { return a + (x * (b- a));}
   }
 }
-//vec3 closepoint = 
-vec4 shift(vec4 p) { return (vec4(p.xyz + (100000 * (p.xyz - lightPos)), 1)); }
+vec4 shift(vec4 p) { return (vec4(p.xyz + (10000 * (p.xyz - lightPos)), 1)); }
 vec4 shiftBy(float x, vec4 p) {
   return (vec4(lightPos + (x * normalize(p.xyz - lightPos)), 1));
 }
-// vec4 shift (vec4 p) { return (vec4 (lightPos +
-// (lumRad.a*normalize(p.xyz-lightPos)), 1));}
 // copied from lighting/cap.geom, should not be changed on its own
 vec4 projNear(vec4 pos) {
   // note we project to a specific height
@@ -34,7 +29,6 @@ vec4 projNear(vec4 pos) {
   return vec4(xy, 100, 1);
 }
 vec4 shiftNear(vec4 pos)
-//{ vec4 sp = shiftBy(radiusUniform,pos);
 {
   vec4 sp = shift(pos);
   if (sp.z > 100) {
@@ -43,19 +37,16 @@ vec4 shiftNear(vec4 pos)
     return sp;
   }
 }
-vec4 f(vec4 p) { return (theMat * p); }
 void main() {
-vec4 p0 = gl_in[0].gl_Position;
-vec4 p1 = gl_in[1].gl_Position;
-vec3 closepoint = closestPointOnSeg3(p0.xyz,p1.xyz,lightPos);
+  vec4 p0 = gl_in[0].gl_Position;
+  vec4 p1 = gl_in[1].gl_Position;
+  vec3 closepoint = closestPointOnSeg3(p0.xyz,p1.xyz,lightPos);
   float ru2 = radiusUniform * radiusUniform;
   vec4 mid = 0.5 * (p0 + p1);
   vec3 n0a = gl_in[2].gl_Position.xyz;
   vec3 n1a = gl_in[3].gl_Position.xyz;
   vec3 n0 = cross(p1.xyz - p0.xyz, n0a - p0.xyz);
   vec3 n1 = cross(p0.xyz - p1.xyz, n1a - p1.xyz);
-
-  // vec3 n2 = n0 + n1; // assumes the summands are normalized
   vec3 lightDir = p0.xyz - lightPos.xyz;
   vec3 lightDir2 = p1.xyz - lightPos.xyz;
   // first test if the edge is part of the silhouette
@@ -66,24 +57,22 @@ vec3 closepoint = closestPointOnSeg3(p0.xyz,p1.xyz,lightPos);
   // using <= rather than < seems to get rid of overlapping shadow
   // artefacts
   {
-    //vec4 p2 = shiftNear(p0);
-    //vec4 p3 = shiftNear(p1);
     vec4 p2 = shiftNear(p0);
     vec4 p3 = shiftNear(p1);
-    gl_Position = f(p0);
+    gl_Position = theMat * p0;
     EmitVertex();
     if (dot(n0, lightDir) > 0) {
-      gl_Position = f(p2);
+      gl_Position = theMat * p2;
       EmitVertex();
-      gl_Position = f(p1);
+      gl_Position = theMat * p1;
       EmitVertex();
     } else {
-      gl_Position = f(p1);
+      gl_Position = theMat * p1;
       EmitVertex();
-      gl_Position = f(p2);
+      gl_Position = theMat * p2;
       EmitVertex();
     }
-    gl_Position = f(p3);
+    gl_Position = theMat * p3;
     EmitVertex();
     EndPrimitive();
   } else {