diff --git a/shader/ceiling/stencil.geom b/shader/ceiling/stencil.geom
new file mode 100644
index 000000000..853734121
--- /dev/null
+++ b/shader/ceiling/stencil.geom
@@ -0,0 +1,13 @@
+#version 450 core
+layout(points) in;
+layout(triangle_strip, max_vertices = 4) out;
+layout(std140, binding = 0) uniform TheMat { mat4 theMat; };
+void main() {
+  vec2 p1 = gl_in[0].gl_Position.xy;
+  vec2 p2 = gl_in[0].gl_Position.zw;
+  gl_Position = theMat * vec4(p1,100,1); EmitVertex();
+  gl_Position = theMat * vec4(p1,5000,1); EmitVertex();
+  gl_Position = theMat * vec4(p2,100,1); EmitVertex();
+  gl_Position = theMat * vec4(p2,5000,1); EmitVertex();
+  EndPrimitive();
+}
diff --git a/shader/ceiling/stencil.vert b/shader/ceiling/stencil.vert
new file mode 100644
index 000000000..ffb827dbb
--- /dev/null
+++ b/shader/ceiling/stencil.vert
@@ -0,0 +1,6 @@
+#version 450 core
+layout (location = 0) in vec4 poss;
+void main()
+{
+  gl_Position = poss;
+}
diff --git a/shader/wall/window.frag b/shader/wall/window.frag
new file mode 100644
index 000000000..6bd962e34
--- /dev/null
+++ b/shader/wall/window.frag
@@ -0,0 +1,14 @@
+#version 450 core
+layout (location=0) out vec4 fCol;
+layout (location=1) out vec4 fPos;
+layout (location=2) out vec4 fNorm;
+in vec4 gColor;
+in vec4 gPos;
+void main()
+{
+  fCol = gColor;
+  //fPos = gPos;// + vec4(0,0,50,0);
+  //fNorm = vec4 (0,0,10,10);
+  fPos = vec4(0,0,50,1);
+  fNorm = vec4 (0,0,10,10);
+}
diff --git a/shader/wall/window.geom b/shader/wall/window.geom
new file mode 100644
index 000000000..0feb2a704
--- /dev/null
+++ b/shader/wall/window.geom
@@ -0,0 +1,33 @@
+#version 450 core
+layout (points) in;
+layout (triangle_strip, max_vertices = 4) out;
+layout (std140, binding = 0) uniform TheMat { mat4 theMat; } ;
+in vec4 vColor [];
+out vec4 gColor;
+out vec4 gPos;
+// consider using isLHS to check if the wall is facing the center
+// this needs the view from point
+float isLHS (vec2 startV, vec2 testV)
+{
+    return sign( -startV.x * testV.y + startV.y * testV.x);
+}
+
+void main()
+{
+  gColor = vColor[0];
+  vec4 p1 = vec4 (gl_in[0].gl_Position.xy,0,1);
+  vec4 p2 = vec4 (gl_in[0].gl_Position.zw,0,1);
+  vec4 a1 = theMat * p1;
+  vec4 a2 = theMat * p2;
+//  if (0 > isLHS (a1.xy - a2.xy, a1.xy - "viewFromPoint")) {
+    vec4 p3 = vec4 (p1.xy,5000,1); //note the random z value, used for GL_DEPTH_CLAMP
+    vec4 p4 = vec4 (p2.xy,5000,1);
+    vec4 a3 = theMat * p3;
+    vec4 a4 = theMat * p4;
+    gPos = p1;gl_Position = a1; EmitVertex();
+    gPos = p3;gl_Position = a3; EmitVertex();
+    gPos = p2;gl_Position = a2; EmitVertex();
+    gPos = p4;gl_Position = a4; EmitVertex();
+    EndPrimitive();
+//  }
+}
diff --git a/shader/wall/window.vert b/shader/wall/window.vert
new file mode 100644
index 000000000..3e9883240
--- /dev/null
+++ b/shader/wall/window.vert
@@ -0,0 +1,9 @@
+#version 450 core
+layout (location = 0) in vec4 poss;
+layout (location = 1) in vec4 color;
+out vec4 vColor;
+void main()
+{
+  gl_Position = poss;
+  vColor = color;
+}