+ // Whether this effect is effectively sampling from a a single texture.
+ // If so, it will override needs_texture_bounce(); however, there are also
+ // two demands it needs to fulfill:
+ //
+ // 1. It needs to be an Input, ie. num_inputs() == 0.
+ // 2. It needs to allocate exactly one sampler in set_gl_state(),
+ // and allow dependent effects to change that sampler state.
+ virtual bool is_single_texture() const { return false; }
+