Add line shadow shader

shader/lighting/occlude.geom

@@ -5,7 +5,7 @@ layout (std140, binding = 0) uniform TheMat { mat4 theMat; } ;
 uniform vec3 lightPos;
 
 vec4 shift (vec4 p)
-{ return vec4 (p.xy + (200 * (p.xy-lightPos.xy)), 0.1 , 1);
+{ return vec4 (p.xy + (200 * (p.xy-lightPos.xy)), (-1) , 1);
 }
 float isLHS (vec2 startV, vec2 testV)
 {
@@ -14,16 +14,16 @@ float isLHS (vec2 startV, vec2 testV)
 // construct a box with openings on bottom face and face away from wall
 void main()
 {
-vec4 p1 = vec4 (gl_in[0].gl_Position.xy,0.1,1);
-vec4 p2 = vec4 (gl_in[0].gl_Position.zw,0.1,1);
+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 - lightPos.xy, p2.xy - lightPos.xy) < 0)
 {
-vec4 p3 = vec4 (p1.xy,-0.5,1);
-vec4 p4 = vec4 (p2.xy,-0.5,1);
+vec4 p3 = vec4 (p1.xy,100,1);
+vec4 p4 = vec4 (p2.xy,100,1);
 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,100,1);
+vec4 p8 = vec4 (p5.xy,100,1);
 
 vec4 a1 = theMat * p1;
 vec4 a2 = theMat * p2;