/*************************************************************************
FILE:   surface.cc
Functions used to generate curves and surfaces.

Author: Dana Vrajitoru, IUSB
Class:  C481 B581 Computer Graphics
**************************************************************************/

#include <cmath>
#include "Point3f.h"

// Builds a circle in the xy plane with given center and radius made
// of 20 points. The first point is repeated a the end to create a
// loop. It stores the points and normals in the last two
// parameters. This is supposed to be drawn as a line strip.
void circleXy(float centerx, float centery, float centerz, float radius,
              vector3f &points, vector3f &normals)
{
    Point3f p, n;
    p[2] = centerz;
    n[2] = 0;
    const int nrPoints = 20;
    float angle =0, delta_angle = 2*M_PI/nrPoints;
    for (int i=0; i<=nrPoints; i++) {
        angle += delta_angle;
        // The normal in the point : we want it to be a unit vector.
        n[0] = cos(angle);
        n[1] = sin(angle);
        // We can use the normat to compute the point itself.
        p[0] = centerx +radius * cos(angle);
        p[1] = centery +radius * sin(angle);
        // Add these to the points and normals.
        points.push_back(p);
        normals.push_back(n);
    }
}

// Draws a curve as a line strip; we have no use for the normals for a
// line strip.
void drawLineStrip(vector3f &points)
{
    glBegin(GL_LINE_STRIP);
    for (int i=0; i<points.size(); i++)
        points[i].glVertex();
    glEnd();
}

// Compute the normals for a curve in the xy plane. You can use the
// function orthogonalXy from the Point3f class. For each 2 line
// segments in a sequence, the normal should be the average of the two
// normals computed on each segment. If the first and last point are
// the same, then the normal in the first and last points should be
void computeNormalsXy(vector3f &points, vector3f &normals)
{;}

// Given a curve with normals in the xy plane, the function builds a
// rotation surface by rotating this curve around the Oy axis. It also
// computes the normals to the surface given the normals to the curve.
void rotationSurfaceY(vector3f &curvePt, vector3f &curveNm, 
                      matrix3f &surfacePt, matrix3f &surfaceNm)
{;}

// Draws the surface given as a grid of points as a sequence of
// triangle strips.
void drawSurface(matrix3f &surfacePt, matrix3f &surfaceNm)
{;}