ENABLE_ALLOW_NEGATIVE_Z -> Fixed picking of sinking object

resources/shaders/picking.fs

@@ -0,0 +1,14 @@
+#version 110
+
+uniform vec4 uniform_color;
+uniform bool viewed_from_top;
+
+varying float world_pos_z;
+
+void main()
+{
+	if (viewed_from_top && world_pos_z < 0.0)
+		discard;
+	
+    gl_FragColor = uniform_color;
+}

resources/shaders/picking.vs

@@ -0,0 +1,11 @@
+#version 110
+
+uniform mat4 world_matrix;
+
+varying float world_pos_z;
+
+void main()
+{
+    world_pos_z = (world_matrix * gl_Vertex).z;
+    gl_Position = ftransform();
+}