// Julien Pilet, Sept. 2008
#include <OpenCV/cv.h>

#include "Meddle/elasticchainondefm.h"


namespace Meddle {


/* ctor */
ElasticChain::ElasticChain(unsigned int npts, float x, float y,
    Model::Animation::Handler *animation):
	m_npts(npts),
	m_first(true),
	m_animation(animation)
{
	m_elastics  = new t_elastic[m_npts - 1];
	m_pts = new t_point[m_npts];
	memset(m_pts, 0, m_npts * sizeof(t_point));

	// orientation et force de la gravite
	gravity[0] = 0;
	gravity[1] = -800;
	float dy = 2 / m_npts; // 2/m_npts espace entre les points du spaghetti
	for (int i = 0; i < m_npts; i++) {
		m_pts[i].mass   = .002;		// poids des maillons intermediaires
		m_pts[i].pos[0] = x;
		m_pts[i].pos[1] = y + i*dy;
	}
	m_pts[0].flags = 10;
	m_pts[m_npts - 1].mass = .02;

	for (int i = 0;i < m_npts - 1; i++) {
		m_elastics[i].p1 = m_pts + i;
		m_elastics[i].p2 = m_pts + i + 1;
		m_elastics[i].factor = 2; //2 ressort plus ou moins rigide
		m_elastics[i].len = dy;
	}
	m_last.start();
}


/* dtor */
ElasticChain::~ElasticChain()
{
	delete[] (m_pts);
	delete[] (m_elastics);
}


void
ElasticChain::draw(float x, float y)
{
	if (m_first) {
		m_first = false;
		return;
	}
	float dtime = m_last.elapsed();

	m_pts[0].pos[0] = x;
	m_pts[0].pos[1] = y;

	dtime = dtime / 32;
	for (int i = 0;i < 32; i++) {
		zero_forces(m_pts, m_npts);
		calc_forces(m_elastics, m_npts - 1);
		advance(m_pts, m_npts, dtime);
	}

	m_animation->texturize();
	m_animation->texture.enable();

	double width = 20;  //20 LARGEUR de la chaine dessine

	glBegin(GL_TRIANGLES);
	glColor4f(1, 1, 1, 1);
	int ndiv = 1;
	int tot = (m_npts - 1) * ndiv;
	int k = 0;
	for (int i = 0;i < m_npts - 1; i++) {
		for (int j = 0;j < ndiv; j++, k++) {
			float t = j / (float)ndiv;
			float r[2];
			float dt[2];
			float nr[2], ndt[2];
			splineCompute(t,2, (i>0? m_pts[i-1].pos:0), m_pts[i].pos, m_pts[i+1].pos,
					(i<m_npts-2? m_pts[i+2].pos:0), r, dt);

			splineCompute(t+1.0f/ndiv,2, (i>0? m_pts[i-1].pos:0), m_pts[i].pos, m_pts[i+1].pos,
					(i<m_npts-2? m_pts[i+2].pos:0), nr, ndt);

			float w = width /sqrt(dt[0]*dt[0]+dt[1]*dt[1]);
			dt[0] *= w;
			dt[1] *= w;
			w = width/sqrt(ndt[0]*ndt[0]+ndt[1]*ndt[1]);
			ndt[0] *= w;
			ndt[1] *= w;

			/*float a[2]= {r[0]-dt[1],r[1]+dt[0]};
			  float b[2]= {r[0]+dt[1],r[1]-dt[0]};
			  float na[2]= {nr[0]-ndt[1],nr[1]+ndt[0]};
			  float nb[2]= {nr[0]+ndt[1],nr[1]-ndt[0]};*/

			float a[2]= {r[0]+80,r[1]-80};
			float b[2]= {r[0]-80,r[1]-80};
			float na[2]= {r[0]+80,r[1]+80};
			float nb[2]= {r[0]-80,r[1]+80};

			float tex = (float)k/(float)tot;
			float texn = (float)(k+1)/(float)tot;
			glTexCoord2f(0,tex);
			glVertex2fv(a);
			glTexCoord2f(1,tex);
			glVertex2fv(b);
			glTexCoord2f(0,texn);
			glVertex2fv(na);
			glTexCoord2f(0,texn);
			glVertex2fv(na);
			glTexCoord2f(1,tex);
			glVertex2fv(b);
			glTexCoord2f(1,texn);
			glVertex2fv(nb);
		}
	}
	glEnd();
	m_animation->texture.disable();
	m_last.restart();
}



} // namespace Meddle