笔试材料收集（二）——用OPENGL搞个冒泡排序，原创_!

冒泡排序，简单的不行，就不解释了。长久没搞OpenGL了，就弄个试试吧。受维基百科的启发，也搞个图形化的输出结果，直观易懂。

#include <time.h>
#include <GL/glew.h>
#include <GL/freeglut.h>

float green = 0.0f;// Represent the color factors of green and blue, to distinguish different array member
const int arrSize = 20;
int arr[arrSize];
int i = 0; //i and j are the loop variables, I make them global
int j = 0;

void CreateRandomList(int* arr, int size)
{
    srand((unsigned)time(NULL));
    for (int i = 0; i < size; i ++)
    {
        arr[i] = rand() % 100;
    }
}

void DisplayList(int* arr, int size)
{
    for (int i = 0; i < size; i ++)
    {
        float x1 = (float)i * 2.0f / (float)size - 1.0f;
        float x2 = ((float)i * 2.0f + 1.0f) / (float)size - 1.0f;
        float y1 = (float)arr[i] * 0.01f;
        float y2 = y1 - 0.05f;
        glColor3f(1.0f, y1, y1);
        glRectf(x1, y1, x2, y2);
    }
}

void BubbleSort(int* arr, const int size)
{
    bool flag = true;
    int temp;
    for (; i < size - 1; i ++)
    {
        flag = true;
        for (; j < size - i - 1; j ++)
        {
            if (arr[j] > arr[j + 1])
            {
                temp = arr[j];
                arr[j] = arr[j + 1];
                arr[j + 1] = temp;
                flag = false;
                break;
            }
        }
        if (j == size - i - 1)
        {
            j = 0;
        }
        if (!flag)
        {
            break;
        }
    }
}

void RenderScene()
{
    glClear(GL_COLOR_BUFFER_BIT);
    glLoadIdentity();
    DisplayList(arr, arrSize);
    glutSwapBuffers();
}

void ChangeSize(int w, int h)
{
    glViewport(0, 0, (GLsizei)w, (GLsizei)h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    double aspecRatio = (double)w / (double)h;
    glOrtho(-aspecRatio, aspecRatio, -1.0, 1.0, 0.0, 1.0);
    glMatrixMode(GL_MODELVIEW);
}

void TimeFunc(int value)
{
    BubbleSort(arr, arrSize);
    glutPostRedisplay();
    glutTimerFunc(200,TimeFunc,0);
}

void initList()
{
    CreateRandomList(arr, arrSize);
}
int main(int argc, char* argv[])
{    
    initList();
    glutInit(&argc, argv);    
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA | GLUT_DEPTH);    
    glutInitWindowSize(800, 600);    
    glutCreateWindow("Bubble Sort Demo");    
    glutReshapeFunc(ChangeSize);     
    glutDisplayFunc(RenderScene);
    glutTimerFunc(200,TimeFunc,0);
    glutMainLoop();    
    return 0;    
}