add missing glsl files

src/osgEarthUtil/ContourMap.frag.glsl

@@ -0,0 +1,15 @@
+#version $GLSL_VERSION_STR
+$GLSL_DEFAULT_PRECISION_FLOAT
+
+#pragma vp_entryPoint "oe_contour_fragment"
+#pragma vp_location   "fragment_coloring"
+
+uniform sampler1D oe_contour_xfer;
+uniform float oe_contour_opacity;
+varying float oe_contour_lookup;
+
+void oe_contour_fragment( inout vec4 color )
+{
+    vec4 texel = texture1D( oe_contour_xfer, oe_contour_lookup );
+    color.rgb = mix(color.rgb, texel.rgb, texel.a * oe_contour_opacity);
+}

src/osgEarthUtil/ContourMap.vert.glsl

@@ -0,0 +1,17 @@
+#version $GLSL_VERSION_STR
+$GLSL_DEFAULT_PRECISION_FLOAT
+
+#pragma vp_entryPoint "oe_contour_vertex"
+#pragma vp_location   "vertex_model"
+
+attribute vec4 oe_terrain_attr;
+uniform float oe_contour_min;
+uniform float oe_contour_range;
+varying float oe_contour_lookup;
+
+void oe_contour_vertex(inout vec4 VertexModel)
+{
+    float height = oe_terrain_attr[3];
+    float height_normalized = (height-oe_contour_min)/oe_contour_range;
+    oe_contour_lookup = clamp( height_normalized, 0.0, 1.0 );
+}