/*
 * Copyright 2011, Blender Foundation.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 */

#include "stdosl.h"

shader node_normal_map(
	normal NormalIn = N,
	float Strength = 1.0,
	color Color = color(0.5, 0.5, 1.0),
	string space = "Tangent",
	string attr_name = "geom:tangent",
	string attr_sign_name = "geom:tangent_sign",
	output normal Normal = NormalIn)
{
	color mcolor = 2.0 * color(Color[0] - 0.5, Color[1] - 0.5, Color[2] - 0.5);

	if (space == "Tangent") {
		vector tangent;
		vector ninterp;
		float tangent_sign;
		float is_smooth;

		getattribute("geom:is_smooth", is_smooth);
		if (!is_smooth)
			ninterp = Ng;

		// get _unnormalized_ interpolated normal and tangent
		if (getattribute(attr_name, tangent) &&
		    getattribute(attr_sign_name, tangent_sign) &&
		    (!is_smooth || getattribute("geom:N", ninterp)))
		{
			// apply normal map
			vector B = tangent_sign * cross(ninterp, tangent);
			Normal = normalize(mcolor[0] * tangent + mcolor[1] * B + mcolor[2] * ninterp);

			// transform to world space
			Normal = normalize(transform("object", "world", Normal));
		}
		else {
			Normal = normal(0, 0, 0);
		}
	}
	else if (space == "Object") {
		Normal = normalize(transform("object", "world", vector(mcolor)));
	}
	else if (space == "World") {
		Normal = normalize(vector(mcolor));
	}
	else if (space == "Blender Object") {
		/* strange blender convention */
		mcolor[1] = -mcolor[1];
		mcolor[2] = -mcolor[2];
	
		Normal = normalize(transform("object", "world", vector(mcolor)));
	}
	else if (space == "Blender World") {
		/* strange blender convention */
		mcolor[1] = -mcolor[1];
		mcolor[2] = -mcolor[2];
	
		Normal = normalize(vector(mcolor));
	}
	
	if (Strength != 1.0)
		Normal = normalize(NormalIn + (Normal - NormalIn) * max(Strength, 0.0));
}