Add surface lighting shader

shader/lighting/surface.frag

@@ -0,0 +1,9 @@
+#version 430 core
+in float lum;
+in vec3 dField;
+out vec4 fColor;
+void main()
+{
+  float c = pow (1 - min(1, dot(dField,dField)) , 2) * lum ;
+  fColor = vec4(c,c,c,c);
+}

shader/lighting/surface.vert

@@ -0,0 +1,13 @@
+#version 430 core
+layout (location = 0) in vec3 position;
+layout (std140, binding = 0) uniform TheMat { mat4 theMat; } ;
+uniform vec3 lightPos;
+uniform vec2 radLum;
+out vec3 dField;
+out float lum;
+void main()
+{
+    dField = (position - lightPos) / radLum.x;
+    lum = radLum.y;
+    gl_Position = theMat * vec4(position,1);
+}