+ Node *find_node_for_effect(Effect *effect) { return node_map[effect]; }
+
+ // Get the OpenGL sampler (GL_TEXTURE0, GL_TEXTURE1, etc.) for the
+ // input of the given node, so that one can modify the sampler state
+ // directly. Only valid to call during set_gl_state().
+ //
+ // Also, for this to be allowed, <node>'s effect must have
+ // needs_texture_bounce() set, so that it samples directly from a
+ // single-sampler input, or from an RTT texture.
+ GLenum get_input_sampler(Node *node, unsigned input_num) const;