Add shader files

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();
+}

shader/ceiling/stencil.vert

@@ -0,0 +1,6 @@
+#version 450 core
+layout (location = 0) in vec4 poss;
+void main()
+{
+  gl_Position = poss;
+}