Lower walls and performance improvement for shadows

shader/wallShadow.geom

@@ -6,29 +6,28 @@ uniform vec2 lightPos;
 uniform mat4 perpMat;
 uniform mat4 worldMat;
 
-vec2 lightPosa = lightPos;
+vec2 lightPosa = ( perpMat * vec4(lightPos,0,1) ).xy;
 
 vec4 shift (vec4 p)
-{ return vec4 (p.xy + (200 * (p.xy-lightPosa)), 0 , 1);
+{ return vec4 (p.xy + (200 * (p.xy-lightPos)), 0 , 1);
 }
 float isLHS (vec2 startV, vec2 testV)
 {
     return sign( -startV.x * testV.y + startV.y * testV.x);
 }
-// construct a box with opening on bottom face
-
+// construct a box with openings on bottom face and face away from wall
 void main()
 {
 vec4 p1 = vec4 (gl_in[0].gl_Position.xy,0,1);
 vec4 p2 = vec4 (gl_in[0].gl_Position.zw,0,1);
-if (isLHS (p1.xy - lightPosa, p2.xy - lightPosa) < 0)
+if (isLHS (p1.xy - lightPos, p2.xy - lightPos) < 0)
 {
-vec4 p3 = vec4 (p1.xy,-0.5,1);
-vec4 p4 = vec4 (p2.xy,-0.5,1);
+vec4 p3 = vec4 (p1.xy,-0.2,1);
+vec4 p4 = vec4 (p2.xy,-0.2,1);
 vec4 p5 = shift(p1);
 vec4 p6 = shift(p2);
-vec4 p7 = vec4 (p6.xy,-0.5,1);
-vec4 p8 = vec4 (p5.xy,-0.5,1);
+vec4 p7 = vec4 (p6.xy,-0.2,1);
+vec4 p8 = vec4 (p5.xy,-0.2,1);
 
 vec4 a1 = perpMat * p1;
 vec4 a2 = perpMat * p2;
@@ -39,6 +38,11 @@ vec4 a6 = perpMat * p6;
 vec4 a7 = perpMat * p7;
 vec4 a8 = perpMat * p8;
 
+//  gl_Position = a1; EmitVertex();
+//  gl_Position = a5; EmitVertex();
+//  gl_Position = a2; EmitVertex();
+//  gl_Position = a6; EmitVertex();
+
   gl_Position = a4; EmitVertex();
   gl_Position = a3; EmitVertex();
   gl_Position = a7; EmitVertex();
@@ -50,7 +54,7 @@ vec4 a8 = perpMat * p8;
   gl_Position = a2; EmitVertex();
   gl_Position = a7; EmitVertex();
   gl_Position = a6; EmitVertex();
-//  gl_Position = a5; EmitVertex();
+
   EndPrimitive();
 } else {}
 }