OpenGL 4 : 一个漂亮的心 For you, My Love

画一个心形有非常多公式能够使用，以下这个公式我觉得最完美了：

float x = R * 16 * pow(sin(theta), 3);
float y = R * (13 * cos(theta) - 5*cos(2*theta) - 2*cos(3*theta) - cos(4*theta));

画出来的心形最美丽，最原始的笛卡尔的心形是个肥心，没这个好看，呵呵。

效果例如以下：

 

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#pragma once
#include <stdio.h>
#include <gl\glew.h>
#include <GL\freeglut.h>
#include "math_3d.h"
#include <cmath>

namespace Tutorial2_Heart
{
  const static float PI = 3.1415926f;
  int gSegments;
  GLuint VBO;

  void genHeart_2(Vector3f *vers, int offset, int segments,
    float ox, float oy, float R = 0.05)
  {
    for (int i = 0; i < segments; i++)
    {
      float theta = 2.0f * PI * float(i) / float(segments);

      float x = R * 16 * pow(sin(theta), 3);
      float y = R * (13 * cos(theta) - 5*cos(2*theta)
        - 2*cos(3*theta) - cos(4*theta));

      vers[offset+i] = Vector3f(ox+x, oy+y, 0.0f);
    }
  }

  void genGeometry()
  {
    const int segments = 360;
    Vector3f vers[segments];
    gSegments = segments;
    genHeart_2(vers, 0, segments, 0.f, 0.f);

    glGenBuffers(1, &VBO);
    glBindBuffer(GL_ARRAY_BUFFER, VBO);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vers), vers, GL_STATIC_DRAW);
  }

  static void renderScene()
  {
    glClear(GL_COLOR_BUFFER_BIT);

    glEnableVertexAttribArray(0);
    glBindBuffer(GL_ARRAY_BUFFER, VBO);
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, 0);

    glDrawArrays(GL_LINE_LOOP, 0, gSegments);

    glDisableVertexAttribArray(0);

    glutSwapBuffers();
  }

  void initCallBack()
  {
    glutDisplayFunc(renderScene);
  }

  int run(int argv, char **argc)
  {
    glutInit(&argv, argc);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA);
    glutInitWindowSize(600, 600);
    glutInitWindowPosition(50, 50);
    glutCreateWindow("Heart Shape");

    initCallBack();

    GLenum res = glewInit();
    if (res != GLEW_OK)
    {
      fprintf(stderr, "Error:'%s'\n", glewGetErrorString(res));
      return 1;
    }

    genGeometry();

    glClearColor(0.8f, 0.1f, 0.1f, 0.0f);

    glutMainLoop();

    return 0;
  }
}