circle.cpp

//#define _USE_MATH_DEFINES

#include <math.h>
#include <cstring>
#include <cstdio>
#include <cstdlib>
#include <GL/gl.h>

#include "shapes.h"

#ifndef M_PI
#define M_PI 3.14159265358979323846
#endif
#ifndef M_TWOPI 
#define M_TWOPI (2 * M_PI)
#endif

circle_blueprint_t::circle_blueprint_t(double radius, double maxArcLength) :
circle_blueprint_t((unsigned int) ceilf((M_TWOPI * radius) / maxArcLength)) {
}

circle_blueprint_t::circle_blueprint_t(unsigned int n) : numOfPoints(n) {
    points = (vector2d*) malloc(n * sizeof (vector2d));

    double angle = M_TWOPI / n;

    for (unsigned int i = 0; i < n; i++) {
        struct vector2d v = {
            cosf(i * angle),
            sinf(i * angle),
        };

        points[i] = v;

        // printf("(%f, %f)\n", v.x, v.y);
    }
}

void circle_blueprint_t::draw(bool opaque) {
    glBegin(opaque ? GL_TRIANGLE_FAN : GL_LINE_LOOP);
    {
        glNormal3f(0, 0, 1);
        if (opaque) {
            // makes all of the following points to
            // fan out of the center.
            glVertex2d(0, 0);
            glTexCoord2f(0.5f, 0.5f);
        }
        for (int i = 0; i < numOfPoints; i++) {
            const vector2d& v = points[i];
            glVertex2d(v.x, v.y);
            glTexCoord2f(v.x / 2 + 1, v.y / 2 + 1);
        }
        if (opaque) {
            // go back to the first vector to connect the last points.
            const vector2d& v = points[0];
            glVertex2d(v.x, v.y);
            glTexCoord2f(v.x / 2 + 1, v.y / 2 + 1);
        }
    }
    glEnd();
}

circle_blueprint_t::~circle_blueprint_t() {
    if (points != NULL) {
        free(points);
    }
}

circle::~circle() {
    if (blueprint) {
        delete blueprint;
    }
}

void circle::draw(bool opaque) {
    glPushMatrix();
    {
        translate();
        // printf("scale = %f\n", radius);
        glScaled(radius, radius, 1);
        blueprint->draw(opaque);
    }
    glPopMatrix();
}

void circle::translate() {
    glTranslated(cx, cy, 0);
}

void circle_blueprint_t::draw(bool opaque, double r) {
    glPushMatrix();
    {
        glScaled(r, r, 1);
        draw(opaque);
    }
    glPopMatrix();
}