/*
 * NodeBillboard.cpp
 *
 * Copyright (C) 1999 Stephen F. White
 * 
 * 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 (see the file "COPYING" for details); if 
 * not, write to the Free Software Foundation, Inc., 675 Mass Ave, 
 * Cambridge, MA 02139, USA.
 */

#include <stdio.h>
#include "stdafx.h"

#include "NodeBillboard.h"
#include "Proto.h"
#include "FieldValue.h"
#include "SFVec3f.h"
#include "MFNode.h"
#include "SFFloat.h"
#include "Matrix.h"
#include "Scene.h"
#include "NodeViewpoint.h"
#include "Util.h"

ProtoBillboard::ProtoBillboard(Scene *scene)
  : Proto(scene, "Billboard")
{
    addEventIn(MFNODE, "addChildren");
    addEventIn(MFNODE, "removeChildren");
    axisOfRotation.set(
          addExposedField(SFVEC3F, "axisOfRotation", new SFVec3f(0, 1, 0)));
    children.set(
          addExposedField(MFNODE, "children", new MFNode(), CHILD_NODE));
    bboxCenter.set(
          addField(SFVEC3F, "bboxCenter", new SFVec3f(0, 0, 0)));
    bboxSize.set(
          addField(SFVEC3F, "bboxSize", new SFVec3f(-1, -1, -1), 
                   new SFFloat(-1.0f)));
}

Node *
ProtoBillboard::create(Scene *scene)
{ 
    return new NodeBillboard(scene, this); 
}

NodeBillboard::NodeBillboard(Scene *scene, Proto *def)
  : Node(scene, def)
{
}

void
NodeBillboard::transform()
{
    Matrix	mat;

    glGetFloatv(GL_MODELVIEW_MATRIX, mat);

    // compute the axis of rotation in eye coordinates
    const float      *a = axisOfRotation()->getValue();

    if (a[0] == 0.0f && a[1] == 0.0f && a[2] == 0.0f) {
	Matrix	mat;
	Vec3f	cam(_scene->getCamera()->getPosition());

	// rotate local Z axis into billboard->viewer vector

	Vec3f	bvec(cam);
	bvec.normalize();
	static const Vec3f	zvec(0.0f, 0.0f, 1.0f);

	Vec3f	axis1(bvec.cross(zvec));
	axis1.normalize();

	float	phi = (float) acos(bvec.dot(zvec));

	glRotatef(-RAD2DEG(phi), axis1.x, axis1.y, axis1.z);
	    
	glGetFloatv(GL_MODELVIEW_MATRIX, mat);
	Vec3f	origin(mat * Vec3f(0.0f, 0.0f, 0.0f));
	Vec3f	yvec(0.0f, 1.0f, 0.0f);
	Vec3f	localy((mat * yvec - origin));
	localy.normalize();

	// rotate local Y axis into up vector
	Vec3f	axis2(localy.cross(yvec));
	axis2.normalize();

	float	theta = (float) acos(localy.dot(yvec));
	glRotatef(RAD2DEG(theta), axis2.x, axis2.y, axis2.z);
    } else {
	// regular billboarding
	// compute the billboard->viewer vector
	Vec3f	origin(mat * Vec3f(0.0f, 0.0f, 0.0f));
	Vec3f	bvec(-origin);
	bvec.normalize();

	// compute the local z axis in eye coordinates
	Vec3f	localz(((mat * Vec3f(0.0f, 0.0f, 1.0f)) - origin));
	localz.normalize();

	Vec3f	axis(((mat * Vec3f(a)) - origin));
	axis.normalize();

	Vec3f	normal(bvec.cross(axis));
	normal.normalize();

	float	theta = (float) asin(localz.dot(normal));

	if (localz.z < 0.0f) theta = PI - theta;

	glRotatef(RAD2DEG(theta), a[0], a[1], a[2]);
    }
}

void
NodeBillboard::draw()
{
    int		i;
    NodeList   *childList = children()->getValues();
    int		n = childList->size();

    glPushMatrix();
    transform();

    for (i = 0; i < n; i++)
	childList->get(i)->bind();

    glPushName(1);			// field
    glPushName(0);			// index
    for (i = 0; i < n; i++) {
	glLoadName(i);
	childList->get(i)->draw();
    }
    glPopName();
    glPopName();

    for (i = 0; i < n; i++)
	childList->get(i)->unbind();

    glPopMatrix();
}

void
NodeBillboard::flip(int index)
{
    bboxCenter()->flip(index);

    NodeList    *childList = children()->getValues();

    for (int i = 0; i < childList->size(); i++)
	childList->get(i)->flip(index);
}

int         
NodeBillboard::countPolygons(void)
{
    int ret = 0;
    NodeList    *childList = children()->getValues();

    for (int i = 0; i < childList->size(); i++)
        ret += childList->get(i)->countPolygons();

    return ret;
}

int         
NodeBillboard::countPrimitives(void)
{
    int ret = 0;
    NodeList    *childList = children()->getValues();

    for (int i = 0; i < childList->size(); i++)
        ret += childList->get(i)->countPrimitives();

    return ret;
}