blender/intern/cycles/render/graph.cpp

/*
 * Copyright 2011-2013 Blender Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "attribute.h"
#include "graph.h"
#include "nodes.h"
#include "shader.h"

#include "util_algorithm.h"
#include "util_debug.h"
#include "util_foreach.h"
#include "util_queue.h"

CCL_NAMESPACE_BEGIN

namespace {

bool check_node_inputs_has_links(const ShaderNode *node)
{
	foreach(const ShaderInput *in, node->inputs) {
		if(in->link) {
			return true;
		}
	}
	return false;
}

bool check_node_inputs_traversed(const ShaderNode *node,
                                 const ShaderNodeSet& done)
{
	foreach(const ShaderInput *in, node->inputs) {
		if(in->link) {
			if(done.find(in->link->parent) == done.end()) {
				return false;
			}
		}
	}
	return true;
}

bool check_node_inputs_equals(const ShaderNode *node_a,
                              const ShaderNode *node_b)
{
	if(node_a->inputs.size() != node_b->inputs.size()) {
		/* Happens with BSDF closure nodes which are currently sharing the same
		 * name for all the BSDF types, making it impossible to filter out
		 * incompatible nodes.
		 */
		return false;
	}
	for(int i = 0; i < node_a->inputs.size(); ++i) {
		ShaderInput *input_a = node_a->inputs[i],
		            *input_b = node_b->inputs[i];
		if(input_a->link == NULL && input_b->link == NULL) {
			/* Unconnected inputs are expected to have the same value. */
			if(input_a->value() != input_b->value()) {
				return false;
			}
		}
		else if(input_a->link != NULL && input_b->link != NULL) {
			/* Expect links are to come from the same exact socket. */
			if(input_a->link != input_b->link) {
				return false;
			}
		}
		else {
			/* One socket has a link and another has not, inputs can't be
			 * considered equal.
			 */
			return false;
		}
	}
	return true;
}

}  /* namespace */

/* Input and Output */

ShaderInput::ShaderInput(ShaderNode *parent_, const char *name, SocketType::Type type)
{
	parent = parent_;
	name_ = name;
	type_ = type;
	link = NULL;
	value_ = make_float3(0.0f, 0.0f, 0.0f);
	stack_offset = SVM_STACK_INVALID;
	flags_ = 0;
}

ShaderOutput::ShaderOutput(ShaderNode *parent_, const char *name, SocketType::Type type)
{
	parent = parent_;
	name_ = name;
	type_ = type;
	stack_offset = SVM_STACK_INVALID;
}

/* Node */

ShaderNode::ShaderNode(const char *name_)
{
	name = name_;
	id = -1;
	bump = SHADER_BUMP_NONE;
	special_type = SHADER_SPECIAL_TYPE_NONE;
}

ShaderNode::~ShaderNode()
{
	foreach(ShaderInput *socket, inputs)
		delete socket;

	foreach(ShaderOutput *socket, outputs)
		delete socket;
}

ShaderInput *ShaderNode::input(const char *name)
{
	foreach(ShaderInput *socket, inputs) {
		if(socket->name() == name)
			return socket;
	}

	return NULL;
}

ShaderOutput *ShaderNode::output(const char *name)
{
	foreach(ShaderOutput *socket, outputs)
		if(socket->name() == name)
			return socket;

	return NULL;
}

ShaderInput *ShaderNode::input(ustring name)
{
	foreach(ShaderInput *socket, inputs) {
		if(socket->name() == name)
			return socket;
	}

	return NULL;
}

ShaderOutput *ShaderNode::output(ustring name)
{
	foreach(ShaderOutput *socket, outputs)
		if(socket->name() == name)
			return socket;

	return NULL;
}

ShaderInput *ShaderNode::add_input(const char *name, SocketType::Type type, float value, int flags)
{
	ShaderInput *input = new ShaderInput(this, name, type);
	input->value_.x = value;
	input->flags_ = flags;
	inputs.push_back(input);
	return input;
}

ShaderInput *ShaderNode::add_input(const char *name, SocketType::Type type, float3 value, int flags)
{
	ShaderInput *input = new ShaderInput(this, name, type);
	input->value_ = value;
	input->flags_ = flags;
	inputs.push_back(input);
	return input;
}

ShaderOutput *ShaderNode::add_output(const char *name, SocketType::Type type)
{
	ShaderOutput *output = new ShaderOutput(this, name, type);
	outputs.push_back(output);
	return output;
}

void ShaderNode::attributes(Shader *shader, AttributeRequestSet *attributes)
{
	foreach(ShaderInput *input, inputs) {
		if(!input->link) {
			if(input->flags() & SocketType::LINK_TEXTURE_GENERATED) {
				if(shader->has_surface)
					attributes->add(ATTR_STD_GENERATED);
				if(shader->has_volume)
					attributes->add(ATTR_STD_GENERATED_TRANSFORM);
			}
			else if(input->flags() & SocketType::LINK_TEXTURE_UV) {
				if(shader->has_surface)
					attributes->add(ATTR_STD_UV);
			}
		}
	}
}

/* Graph */

ShaderGraph::ShaderGraph()
{
	finalized = false;
	num_node_ids = 0;
	add(new OutputNode());
}

ShaderGraph::~ShaderGraph()
{
	clear_nodes();
}

ShaderNode *ShaderGraph::add(ShaderNode *node)
{
	assert(!finalized);
	node->id = num_node_ids++;
	nodes.push_back(node);
	return node;
}

OutputNode *ShaderGraph::output()
{
	return (OutputNode*)nodes.front();
}

ShaderGraph *ShaderGraph::copy()
{
	ShaderGraph *newgraph = new ShaderGraph();

	/* copy nodes */
	ShaderNodeSet nodes_all;
	foreach(ShaderNode *node, nodes)
		nodes_all.insert(node);

	ShaderNodeMap nodes_copy;
	copy_nodes(nodes_all, nodes_copy);

	/* add nodes (in same order, so output is still first) */
	newgraph->clear_nodes();
	foreach(ShaderNode *node, nodes)
		newgraph->add(nodes_copy[node]);

	return newgraph;
}

void ShaderGraph::connect(ShaderOutput *from, ShaderInput *to)
{
	assert(!finalized);
	assert(from && to);

	if(to->link) {
		fprintf(stderr, "Cycles shader graph connect: input already connected.\n");
		return;
	}

	if(from->type() != to->type()) {
		/* for closures we can't do automatic conversion */
		if(from->type() == SocketType::CLOSURE || to->type() == SocketType::CLOSURE) {
			fprintf(stderr, "Cycles shader graph connect: can only connect closure to closure "
			        "(%s.%s to %s.%s).\n",
			        from->parent->name.c_str(), from->name().c_str(),
			        to->parent->name.c_str(), to->name().c_str());
			return;
		}

		/* add automatic conversion node in case of type mismatch */
		ShaderNode *convert = add(new ConvertNode(from->type(), to->type(), true));

		connect(from, convert->inputs[0]);
		connect(convert->outputs[0], to);
	}
	else {
		/* types match, just connect */
		to->link = from;
		from->links.push_back(to);
	}
}

void ShaderGraph::disconnect(ShaderInput *to)
{
	assert(!finalized);
	assert(to->link);

	ShaderOutput *from = to->link;

	to->link = NULL;
	from->links.erase(remove(from->links.begin(), from->links.end(), to), from->links.end());
}

void ShaderGraph::relink(ShaderNode *node, ShaderOutput *from, ShaderOutput *to)
{
	/* Copy because disconnect modifies this list */
	vector<ShaderInput*> outputs = from->links;

	/* Bypass node by moving all links from "from" to "to" */
	foreach(ShaderInput *sock, node->inputs) {
		if(sock->link)
			disconnect(sock);
	}

	foreach(ShaderInput *sock, outputs) {
		disconnect(sock);
		if(to)
			connect(to, sock);
	}
}

void ShaderGraph::finalize(Scene *scene,
                           bool do_bump,
                           bool do_osl,
                           bool do_simplify)
{
	/* before compiling, the shader graph may undergo a number of modifications.
	 * currently we set default geometry shader inputs, and create automatic bump
	 * from displacement. a graph can be finalized only once, and should not be
	 * modified afterwards. */

	if(!finalized) {
		clean(scene);
		default_inputs(do_osl);
		refine_bump_nodes();

		if(do_bump)
			bump_from_displacement();

		ShaderInput *surface_in = output()->input("Surface");
		ShaderInput *volume_in = output()->input("Volume");

		/* todo: make this work when surface and volume closures are tangled up */

		if(surface_in->link)
			transform_multi_closure(surface_in->link->parent, NULL, false);
		if(volume_in->link)
			transform_multi_closure(volume_in->link->parent, NULL, true);

		finalized = true;
	}
	else if(do_simplify) {
		simplify_settings(scene);
	}
}

void ShaderGraph::find_dependencies(ShaderNodeSet& dependencies, ShaderInput *input)
{
	/* find all nodes that this input depends on directly and indirectly */
	ShaderNode *node = (input->link)? input->link->parent: NULL;

	if(node != NULL && dependencies.find(node) == dependencies.end()) {
		foreach(ShaderInput *in, node->inputs)
			find_dependencies(dependencies, in);

		dependencies.insert(node);
	}
}

void ShaderGraph::clear_nodes()
{
	foreach(ShaderNode *node, nodes) {
		delete node;
	}
	nodes.clear();
}

void ShaderGraph::copy_nodes(ShaderNodeSet& nodes, ShaderNodeMap& nnodemap)
{
	/* copy a set of nodes, and the links between them. the assumption is
	 * made that all nodes that inputs are linked to are in the set too. */

	/* copy nodes */
	foreach(ShaderNode *node, nodes) {
		ShaderNode *nnode = node->clone();
		nnodemap[node] = nnode;

		nnode->inputs.clear();
		nnode->outputs.clear();

		foreach(ShaderInput *input, node->inputs) {
			ShaderInput *ninput = new ShaderInput(*input);
			nnode->inputs.push_back(ninput);

			ninput->parent = nnode;
			ninput->link = NULL;
		}

		foreach(ShaderOutput *output, node->outputs) {
			ShaderOutput *noutput = new ShaderOutput(*output);
			nnode->outputs.push_back(noutput);

			noutput->parent = nnode;
			noutput->links.clear();
		}
	}

	/* recreate links */
	foreach(ShaderNode *node, nodes) {
		foreach(ShaderInput *input, node->inputs) {
			if(input->link) {
				/* find new input and output */
				ShaderNode *nfrom = nnodemap[input->link->parent];
				ShaderNode *nto = nnodemap[input->parent];
				ShaderOutput *noutput = nfrom->output(input->link->name());
				ShaderInput *ninput = nto->input(input->name());

				/* connect */
				connect(noutput, ninput);
			}
		}
	}
}

/* Graph simplification */
/* ******************** */

/* Step 1: Remove proxy nodes.
 * These only exists temporarily when exporting groups, and we must remove them
 * early so that node->attributes() and default links do not see them.
 */
void ShaderGraph::remove_proxy_nodes()
{
	vector<bool> removed(num_node_ids, false);
	bool any_node_removed = false;

	foreach(ShaderNode *node, nodes) {
		if(node->special_type == SHADER_SPECIAL_TYPE_PROXY) {
			ConvertNode *proxy = static_cast<ConvertNode*>(node);
			ShaderInput *input = proxy->inputs[0];
			ShaderOutput *output = proxy->outputs[0];

			/* bypass the proxy node */
			if(input->link) {
				relink(proxy, output, input->link);
			}
			else {
				/* Copy because disconnect modifies this list */
				vector<ShaderInput*> links(output->links);

				foreach(ShaderInput *to, links) {
					/* remove any autoconvert nodes too if they lead to
					 * sockets with an automatically set default value */
					ShaderNode *tonode = to->parent;

					if(tonode->special_type == SHADER_SPECIAL_TYPE_AUTOCONVERT) {
						bool all_links_removed = true;
						vector<ShaderInput*> links = tonode->outputs[0]->links;

						foreach(ShaderInput *autoin, links) {
							if(autoin->flags() & SocketType::DEFAULT_LINK_MASK)
								disconnect(autoin);
							else
								all_links_removed = false;
						}

						if(all_links_removed)
							removed[tonode->id] = true;
					}

					disconnect(to);

					/* transfer the default input value to the target socket */
					to->set(input->value());
					to->set(input->value_string());
				}
			}

			removed[proxy->id] = true;
			any_node_removed = true;
		}
	}

	/* remove nodes */
	if(any_node_removed) {
		list<ShaderNode*> newnodes;

		foreach(ShaderNode *node, nodes) {
			if(!removed[node->id])
				newnodes.push_back(node);
			else
				delete node;
		}

		nodes = newnodes;
	}
}

/* Step 2: Constant folding.
 * Try to constant fold some nodes, and pipe result directly to
 * the input socket of connected nodes.
 */
void ShaderGraph::constant_fold()
{
	ShaderNodeSet done, scheduled;
	queue<ShaderNode*> traverse_queue;

	/* Schedule nodes which doesn't have any dependencies. */
	foreach(ShaderNode *node, nodes) {
		if(!check_node_inputs_has_links(node)) {
			traverse_queue.push(node);
			scheduled.insert(node);
		}
	}

	while(!traverse_queue.empty()) {
		ShaderNode *node = traverse_queue.front();
		traverse_queue.pop();
		done.insert(node);
		foreach(ShaderOutput *output, node->outputs) {
			if(output->links.size() == 0) {
				continue;
			}
			/* Schedule node which was depending on the value,
			 * when possible. Do it before disconnect.
			 */
			foreach(ShaderInput *input, output->links) {
				if(scheduled.find(input->parent) != scheduled.end()) {
					/* Node might not be optimized yet but scheduled already
					 * by other dependencies. No need to re-schedule it.
					 */
					continue;
				}
				/* Schedule node if its inputs are fully done. */
				if(check_node_inputs_traversed(input->parent, done)) {
					traverse_queue.push(input->parent);
					scheduled.insert(input->parent);
				}
			}
			/* Optimize current node. */
			if(node->constant_fold(this, output, output->links[0])) {
				/* Apply optimized value to other connected sockets and disconnect. */
				vector<ShaderInput*> links(output->links);
				for(size_t i = 0; i < links.size(); i++) {
					if(i > 0)
						links[i]->set(links[0]->value());
					disconnect(links[i]);
				}
			}
		}
	}
}

/* Step 3: Simplification. */
void ShaderGraph::simplify_settings(Scene *scene)
{
	foreach(ShaderNode *node, nodes) {
		node->simplify_settings(scene);
	}
}

/* Step 4: Deduplicate nodes with same settings. */
void ShaderGraph::deduplicate_nodes()
{
	/* NOTES:
	 * - Deduplication happens for nodes which has same exact settings and same
	 *   exact input links configuration (either connected to same output or has
	 *   the same exact default value).
	 * - Deduplication happens in the bottom-top manner, so we know for fact that
	 *   all traversed nodes are either can not be deduplicated at all or were
	 *   already deduplicated.
	 */

	ShaderNodeSet scheduled;
	map<ustring, ShaderNodeSet> done;
	queue<ShaderNode*> traverse_queue;

	/* Schedule nodes which doesn't have any dependencies. */
	foreach(ShaderNode *node, nodes) {
		if(!check_node_inputs_has_links(node)) {
			traverse_queue.push(node);
			scheduled.insert(node);
		}
	}

	while(!traverse_queue.empty()) {
		ShaderNode *node = traverse_queue.front();
		traverse_queue.pop();
		done[node->name].insert(node);
		/* Schedule the nodes which were depending on the current node. */
		foreach(ShaderOutput *output, node->outputs) {
			foreach(ShaderInput *input, output->links) {
				if(scheduled.find(input->parent) != scheduled.end()) {
					/* Node might not be optimized yet but scheduled already
					 * by other dependencies. No need to re-schedule it.
					 */
					continue;
				}
				/* Schedule node if its inputs are fully done. */
				if(check_node_inputs_traversed(input->parent, done[input->parent->name])) {
					traverse_queue.push(input->parent);
					scheduled.insert(input->parent);
				}
			}
		}
		/* Try to merge this node with another one. */
		foreach(ShaderNode *other_node, done[node->name]) {
			if(node == other_node) {
				/* Don't merge with self. */
				continue;
			}
			if(node->name != other_node->name) {
				/* Can only de-duplicate nodes of the same type. */
				continue;
			}
			if(!check_node_inputs_equals(node, other_node)) {
				/* Node inputs are different, can't merge them, */
				continue;
			}
			if(!node->equals(other_node)) {
				/* Node settings are different. */
				continue;
			}
			/* TODO(sergey): Consider making it an utility function. */
			for(int i = 0; i < node->outputs.size(); ++i) {
				relink(node, node->outputs[i], other_node->outputs[i]);
			}
			break;
		}
	}
}

void ShaderGraph::break_cycles(ShaderNode *node, vector<bool>& visited, vector<bool>& on_stack)
{
	visited[node->id] = true;
	on_stack[node->id] = true;

	foreach(ShaderInput *input, node->inputs) {
		if(input->link) {
			ShaderNode *depnode = input->link->parent;

			if(on_stack[depnode->id]) {
				/* break cycle */
				disconnect(input);
				fprintf(stderr, "Cycles shader graph: detected cycle in graph, connection removed.\n");
			}
			else if(!visited[depnode->id]) {
				/* visit dependencies */
				break_cycles(depnode, visited, on_stack);
			}
		}
	}

	on_stack[node->id] = false;
}

void ShaderGraph::clean(Scene *scene)
{
	/* Graph simplification */

	/* 1: Remove proxy nodes was already done. */

	/* 2: Constant folding. */
	constant_fold();

	/* 3: Simplification. */
	simplify_settings(scene);

	/* 4: De-duplication. */
	deduplicate_nodes();

	/* we do two things here: find cycles and break them, and remove unused
	 * nodes that don't feed into the output. how cycles are broken is
	 * undefined, they are invalid input, the important thing is to not crash */

	vector<bool> visited(num_node_ids, false);
	vector<bool> on_stack(num_node_ids, false);
	
	/* break cycles */
	break_cycles(output(), visited, on_stack);

	/* disconnect unused nodes */
	foreach(ShaderNode *node, nodes) {
		if(!visited[node->id]) {
			foreach(ShaderInput *to, node->inputs) {
				ShaderOutput *from = to->link;

				if(from) {
					to->link = NULL;
					from->links.erase(remove(from->links.begin(), from->links.end(), to), from->links.end());
				}
			}
		}
	}

	/* remove unused nodes */
	list<ShaderNode*> newnodes;

	foreach(ShaderNode *node, nodes) {
		if(visited[node->id])
			newnodes.push_back(node);
		else
			delete node;
	}

	nodes = newnodes;
}

void ShaderGraph::default_inputs(bool do_osl)
{
	/* nodes can specify default texture coordinates, for now we give
	 * everything the position by default, except for the sky texture */

	ShaderNode *geom = NULL;
	ShaderNode *texco = NULL;

	foreach(ShaderNode *node, nodes) {
		foreach(ShaderInput *input, node->inputs) {
			if(!input->link && (!(input->flags() & SocketType::OSL_INTERNAL) || do_osl)) {
				if(input->flags() & SocketType::LINK_TEXTURE_GENERATED) {
					if(!texco)
						texco = new TextureCoordinateNode();

					connect(texco->output("Generated"), input);
				}
				else if(input->flags() & SocketType::LINK_TEXTURE_UV) {
					if(!texco)
						texco = new TextureCoordinateNode();

					connect(texco->output("UV"), input);
				}
				else if(input->flags() & SocketType::LINK_INCOMING) {
					if(!geom)
						geom = new GeometryNode();

					connect(geom->output("Incoming"), input);
				}
				else if(input->flags() & SocketType::LINK_NORMAL) {
					if(!geom)
						geom = new GeometryNode();

					connect(geom->output("Normal"), input);
				}
				else if(input->flags() & SocketType::LINK_POSITION) {
					if(!geom)
						geom = new GeometryNode();

					connect(geom->output("Position"), input);
				}
				else if(input->flags() & SocketType::LINK_TANGENT) {
					if(!geom)
						geom = new GeometryNode();

					connect(geom->output("Tangent"), input);
				}
			}
		}
	}

	if(geom)
		add(geom);
	if(texco)
		add(texco);
}

void ShaderGraph::refine_bump_nodes()
{
	/* we transverse the node graph looking for bump nodes, when we find them,
	 * like in bump_from_displacement(), we copy the sub-graph defined from "bump"
	 * input to the inputs "center","dx" and "dy" What is in "bump" input is moved
	 * to "center" input. */

	foreach(ShaderNode *node, nodes) {
		if(node->special_type == SHADER_SPECIAL_TYPE_BUMP && node->input("Height")->link) {
			ShaderInput *bump_input = node->input("Height");
			ShaderNodeSet nodes_bump;

			/* make 2 extra copies of the subgraph defined in Bump input */
			ShaderNodeMap nodes_dx;
			ShaderNodeMap nodes_dy;

			/* find dependencies for the given input */
			find_dependencies(nodes_bump, bump_input);

			copy_nodes(nodes_bump, nodes_dx);
			copy_nodes(nodes_bump, nodes_dy);
	
			/* mark nodes to indicate they are use for bump computation, so
			   that any texture coordinates are shifted by dx/dy when sampling */
			foreach(ShaderNode *node, nodes_bump)
				node->bump = SHADER_BUMP_CENTER;
			foreach(NodePair& pair, nodes_dx)
				pair.second->bump = SHADER_BUMP_DX;
			foreach(NodePair& pair, nodes_dy)
				pair.second->bump = SHADER_BUMP_DY;

			ShaderOutput *out = bump_input->link;
			ShaderOutput *out_dx = nodes_dx[out->parent]->output(out->name());
			ShaderOutput *out_dy = nodes_dy[out->parent]->output(out->name());

			connect(out_dx, node->input("SampleX"));
			connect(out_dy, node->input("SampleY"));
			
			/* add generated nodes */
			foreach(NodePair& pair, nodes_dx)
				add(pair.second);
			foreach(NodePair& pair, nodes_dy)
				add(pair.second);
			
			/* connect what is connected is bump to samplecenter input*/
			connect(out , node->input("SampleCenter"));

			/* bump input is just for connectivity purpose for the graph input,
			 * we re-connected this input to samplecenter, so lets disconnect it
			 * from bump input */
			disconnect(bump_input);
		}
	}
}

void ShaderGraph::bump_from_displacement()
{
	/* generate bump mapping automatically from displacement. bump mapping is
	 * done using a 3-tap filter, computing the displacement at the center,
	 * and two other positions shifted by ray differentials.
	 *
	 * since the input to displacement is a node graph, we need to ensure that
	 * all texture coordinates use are shift by the ray differentials. for this
	 * reason we make 3 copies of the node subgraph defining the displacement,
	 * with each different geometry and texture coordinate nodes that generate
	 * different shifted coordinates.
	 *
	 * these 3 displacement values are then fed into the bump node, which will
	 * output the perturbed normal. */

	ShaderInput *displacement_in = output()->input("Displacement");

	if(!displacement_in->link)
		return;
	
	/* find dependencies for the given input */
	ShaderNodeSet nodes_displace;
	find_dependencies(nodes_displace, displacement_in);

	/* copy nodes for 3 bump samples */
	ShaderNodeMap nodes_center;
	ShaderNodeMap nodes_dx;
	ShaderNodeMap nodes_dy;

	copy_nodes(nodes_displace, nodes_center);
	copy_nodes(nodes_displace, nodes_dx);
	copy_nodes(nodes_displace, nodes_dy);

	/* mark nodes to indicate they are use for bump computation, so
	 * that any texture coordinates are shifted by dx/dy when sampling */
	foreach(NodePair& pair, nodes_center)
		pair.second->bump = SHADER_BUMP_CENTER;
	foreach(NodePair& pair, nodes_dx)
		pair.second->bump = SHADER_BUMP_DX;
	foreach(NodePair& pair, nodes_dy)
		pair.second->bump = SHADER_BUMP_DY;

	/* add set normal node and connect the bump normal ouput to the set normal
	 * output, so it can finally set the shader normal, note we are only doing
	 * this for bump from displacement, this will be the only bump allowed to
	 * overwrite the shader normal */
	ShaderNode *set_normal = add(new SetNormalNode());
	
	/* add bump node and connect copied graphs to it */
	ShaderNode *bump = add(new BumpNode());

	ShaderOutput *out = displacement_in->link;
	ShaderOutput *out_center = nodes_center[out->parent]->output(out->name());
	ShaderOutput *out_dx = nodes_dx[out->parent]->output(out->name());
	ShaderOutput *out_dy = nodes_dy[out->parent]->output(out->name());

	connect(out_center, bump->input("SampleCenter"));
	connect(out_dx, bump->input("SampleX"));
	connect(out_dy, bump->input("SampleY"));
	
	/* connect the bump out to the set normal in: */
	connect(bump->output("Normal"), set_normal->input("Direction"));

	/* connect bump output to normal input nodes that aren't set yet. actually
	 * this will only set the normal input to the geometry node that we created
	 * and connected to all other normal inputs already. */
	foreach(ShaderNode *node, nodes) {
		/* Don't connect normal to the bump node we're coming from,
		 * otherwise it'll be a cycle in graph.
		 */
		if(node == bump) {
			continue;
		}
		foreach(ShaderInput *input, node->inputs) {
			if(!input->link && (input->flags() & SocketType::LINK_NORMAL))
				connect(set_normal->output("Normal"), input);
		}
	}

	/* for displacement bump, clear the normal input in case the above loop
	 * connected the setnormal out to the bump normalin */
	ShaderInput *bump_normal_in = bump->input("Normal");
	if(bump_normal_in)
		bump_normal_in->link = NULL;

	/* finally, add the copied nodes to the graph. we can't do this earlier
	 * because we would create dependency cycles in the above loop */
	foreach(NodePair& pair, nodes_center)
		add(pair.second);
	foreach(NodePair& pair, nodes_dx)
		add(pair.second);
	foreach(NodePair& pair, nodes_dy)
		add(pair.second);
}

void ShaderGraph::transform_multi_closure(ShaderNode *node, ShaderOutput *weight_out, bool volume)
{
	/* for SVM in multi closure mode, this transforms the shader mix/add part of
	 * the graph into nodes that feed weights into closure nodes. this is too
	 * avoid building a closure tree and then flattening it, and instead write it
	 * directly to an array */
	
	if(node->special_type == SHADER_SPECIAL_TYPE_COMBINE_CLOSURE) {
		ShaderInput *fin = node->input("Fac");
		ShaderInput *cl1in = node->input("Closure1");
		ShaderInput *cl2in = node->input("Closure2");
		ShaderOutput *weight1_out, *weight2_out;

		if(fin) {
			/* mix closure: add node to mix closure weights */
			ShaderNode *mix_node = add(new MixClosureWeightNode());
			ShaderInput *fac_in = mix_node->input("Fac"); 
			ShaderInput *weight_in = mix_node->input("Weight"); 

			if(fin->link)
				connect(fin->link, fac_in);
			else
				fac_in->set(fin->value_float());

			if(weight_out)
				connect(weight_out, weight_in);

			weight1_out = mix_node->output("Weight1");
			weight2_out = mix_node->output("Weight2");
		}
		else {
			/* add closure: just pass on any weights */
			weight1_out = weight_out;
			weight2_out = weight_out;
		}

		if(cl1in->link)
			transform_multi_closure(cl1in->link->parent, weight1_out, volume);
		if(cl2in->link)
			transform_multi_closure(cl2in->link->parent, weight2_out, volume);
	}
	else {
		ShaderInput *weight_in = node->input((volume)? "VolumeMixWeight": "SurfaceMixWeight");

		/* not a closure node? */
		if(!weight_in)
			return;

		/* already has a weight connected to it? add weights */
		if(weight_in->link || weight_in->value_float() != 0.0f) {
			ShaderNode *math_node = add(new MathNode());
			ShaderInput *value1_in = math_node->input("Value1");
			ShaderInput *value2_in = math_node->input("Value2");

			if(weight_in->link)
				connect(weight_in->link, value1_in);
			else
				value1_in->set(weight_in->value_float());

			if(weight_out)
				connect(weight_out, value2_in);
			else
				value2_in->set(1.0f);

			weight_out = math_node->output("Value");
			if(weight_in->link)
				disconnect(weight_in);
		}

		/* connected to closure mix weight */
		if(weight_out)
			connect(weight_out, weight_in);
		else
			weight_in->set(weight_in->value_float() + 1.0f);
	}
}

int ShaderGraph::get_num_closures()
{
	int num_closures = 0;
	foreach(ShaderNode *node, nodes) {
		ClosureType closure_type = node->get_closure_type();
		if(closure_type == CLOSURE_NONE_ID) {
			continue;
		}
		else if(CLOSURE_IS_BSSRDF(closure_type)) {
			num_closures += 3;
		}
		else if(CLOSURE_IS_GLASS(closure_type)) {
			num_closures += 2;
		}
		else {
			++num_closures;
		}
	}
	return num_closures;
}

void ShaderGraph::dump_graph(const char *filename)
{
	FILE *fd = fopen(filename, "w");

	if(fd == NULL) {
		printf("Error opening file for dumping the graph: %s\n", filename);
		return;
	}

	fprintf(fd, "digraph shader_graph {\n");
	fprintf(fd, "ranksep=1.5\n");
	fprintf(fd, "rankdir=LR\n");
	fprintf(fd, "splines=false\n");

	foreach(ShaderNode *node, nodes) {
		fprintf(fd, "// NODE: %p\n", node);
		fprintf(fd, "\"%p\" [shape=record,label=\"{", node);
		if(node->inputs.size()) {
			fprintf(fd, "{");
			foreach(ShaderInput *socket, node->inputs) {
				if(socket != node->inputs[0]) {
					fprintf(fd, "|");
				}
				fprintf(fd, "<IN_%p>%s", socket, socket->name().c_str());
			}
			fprintf(fd, "}|");
		}
		fprintf(fd, "%s", node->name.c_str());
		if(node->bump == SHADER_BUMP_CENTER) {
			fprintf(fd, " (bump:center)");
		}
		else if(node->bump == SHADER_BUMP_DX) {
			fprintf(fd, " (bump:dx)");
		}
		else if(node->bump == SHADER_BUMP_DY) {
			fprintf(fd, " (bump:dy)");
		}
		if(node->outputs.size()) {
			fprintf(fd, "|{");
			foreach(ShaderOutput *socket, node->outputs) {
				if(socket != node->outputs[0]) {
					fprintf(fd, "|");
				}
				fprintf(fd, "<OUT_%p>%s", socket, socket->name().c_str());
			}
			fprintf(fd, "}");
		}
		fprintf(fd, "}\"]");
	}

	foreach(ShaderNode *node, nodes) {
		foreach(ShaderOutput *output, node->outputs) {
			foreach(ShaderInput *input, output->links) {
				fprintf(fd,
				        "// CONNECTION: OUT_%p->IN_%p (%s:%s)\n",
				        output,
				        input,
				        output->name().c_str(), input->name().c_str());
				fprintf(fd,
				        "\"%p\":\"OUT_%p\":e -> \"%p\":\"IN_%p\":w [label=\"\"]\n",
				        output->parent,
				        output,
				        input->parent,
				        input);
			}
		}
	}

	fprintf(fd, "}\n");
	fclose(fd);
}

CCL_NAMESPACE_END