#include <cylinder.h>
#include <QDebug>

using namespace std;


static void push_vertex(vector<GLfloat> &verts,
						GLfloat x, GLfloat y, GLfloat z,
						Color c) {
	verts.push_back(x);
	verts.push_back(y);
	verts.push_back(z);
	verts.push_back(c.r);
	verts.push_back(c.g);
	verts.push_back(c.b);
}


Cylinder::Cylinder(float ep, float r, unsigned nb_fac, Color c)
	:ep(ep),
	 r(r),
	 nb_fac(nb_fac),
	 c(c),
	 angle(2*M_PI/nb_fac),
	 face_size(nb_fac * 3),
	 side_size((nb_fac+1) * 2)
{
	vector<GLfloat> verts((2*face_size + side_size) * 3 * 2);
	build_faces(verts);
	build_side(verts);
	vbo.create();
	qDebug() << "verts.size() " << verts.size()
			 << "nb_fac:" << nb_fac
			 << "face_size:" << face_size
			 << "side_size:" << side_size;
	vbo.bind();
	vbo.allocate(verts.data(), verts.size() * sizeof (GLfloat));
	vbo.release();
}



void Cylinder::build_face(float z, vector<GLfloat> &verts)
{
	Color color(c);
	for (unsigned j = 0; j < nb_fac; j++) {
		push_vertex(verts, 0, 0, z, color);
		push_vertex(verts, cos(angle*j) * r, sin(angle*j) * r, z, color);
		push_vertex(verts, cos(angle*(j+1)) * r, sin(angle*(j+1)) * r, z, color);
		if (j % (nb_fac/4) == 0) {
			if (j % (nb_fac/2) == 0) {
				color.r *= .8;
				color.g *= .8;
				color.b *= .8;
			}
			else {
				color = c;
			}
		}
	}
}


void Cylinder::build_faces(vector<GLfloat> &verts)
{
	build_face(-ep/2, verts);
	build_face(ep/2, verts);
}


void Cylinder::build_side(vector<GLfloat> &verts)
{
	Color color(c.r*.7, c.g*.7, c.b*.7);
	for (unsigned i = 0; i < nb_fac+1; i++) {
		push_vertex(verts, cos(angle*i) * r, sin(angle*i) * r, -ep/2, color);
		push_vertex(verts, cos(angle*i) * r, sin(angle*i) * r, ep/2, color);
	}
}


void Cylinder::draw(QOpenGLFunctions &f, int pos, int col)
{
	vbo.bind();
	f.glEnableVertexAttribArray(pos);
	f.glVertexAttribPointer(pos, 3, GL_FLOAT, GL_FALSE,
							3 * sizeof (GLfloat),
							nullptr);
	f.glEnableVertexAttribArray(col);
	f.glVertexAttribPointer(col, 3, GL_FLOAT, GL_FALSE,
							3 * sizeof (GLfloat),
							(void *) (3 * sizeof (GLfloat)));
	f.glDrawArrays(GL_TRIANGLES, 0, face_size);
	f.glDrawArrays(GL_TRIANGLES, face_size, face_size);
	f.glDrawArrays(GL_QUAD_STRIP,
				   face_size * 2,
				   side_size);
	f.glDisableVertexAttribArray(pos);
	f.glDisableVertexAttribArray(col);
	vbo.release();
}