图形学：Opengl圆和多边形的绘制
1、采用中点Bresenham算法实现带颜色的圆绘制，同时采用OpenGL库函数实现带颜色的圆的绘制。
2、采用X-扫描线算法/改进的x-扫描线算法/边缘填充算法/教材或文献中其他算法实现六边形绘制，同时采用OpenGL库函数实现带颜色的六边形绘制。
// ConsoleApplication2.cpp : 定义控制台应用程序的入口点。
//
#include "stdafx.h"
#include "stdio.h"
#include #include "stdafx.h"
#include
#include"stdafx.h"
#include
#include
const int POINTNUM = 6; //多边形点数.
/******定义结构体用于活性边表AET和新边表NET***********************************/
typedef struct XET
{
float x;
float dx, ymax;
XET* next;
} AET, NET;
/******定义点结构体point******************************************************/
struct point
{
float x;
float y;
} polypoint[POINTNUM] = { { 250,10 },{ 550,150 },{ 550,400 },{ 250,250 },{ 100,350 },{ 120,200 } }; //多边形顶点
void PolyScan()
{
/******计算最高点的y坐标(扫描到此结束)****************************************/
int MaxY = 0;
int i;
for (i = 0; i<POINTNUM; i++)
if (polypoint[i].y>MaxY)
MaxY = polypoint[i].y;
/*******初始化AET表***********************************************************/
AET *pAET = new AET;
pAET->next = NULL;
/******初始化NET表************************************************************/
NET *pNET[1024];
for (i = 0; i <= MaxY; i++)
{
pNET[i] = new NET;
pNET[i]->next = NULL;
}
glClear(GL_COLOR_BUFFER_BIT); //赋值的窗口显示.
glColor3f(0.0, 0.0, 0.0); //设置直线的颜色红色
glBegin(GL_POINTS);
/******扫描并建立NET表*********************************************************/
for (i = 0; i <= MaxY; i++)
{
for (int j = 0; j<POINTNUM; j++)
if (polypoint[j].y == i)
{
//一个点跟前面的一个点形成一条线段，跟后面的点也形成线段
if (polypoint[(j - 1 + POINTNUM) % POINTNUM].y>polypoint[j].y)
{
NET *p = new NET;
p->x = polypoint[j].x;
p->ymax = polypoint[(j - 1 + POINTNUM) % POINTNUM].y;
p->dx = (polypoint[(j - 1 + POINTNUM) % POINTNUM].x - polypoint[j].x) / (polypoint[(j - 1 + POINTNUM) % POINTNUM].y - polypoint[j].y);
p->next = pNET[i]->next;
pNET[i]->next = p;
}
if (polypoint[(j + 1 + POINTNUM) % POINTNUM].y>polypoint[j].y)
{
NET *p = new NET;
p->x = polypoint[j].x;
p->ymax = polypoint[(j + 1 + POINTNUM) % POINTNUM].y;
p->dx = (polypoint[(j + 1 + POINTNUM) % POINTNUM].x - polypoint[j].x) / (polypoint[(j + 1 + POINTNUM) % POINTNUM].y - polypoint[j].y);
p->next = pNET[i]->next;
pNET[i]->next = p;
}
}
}
/******建立并更新活性边表AET*****************************************************/
for (i = 0; i <= MaxY; i++)
{
//计算新的交点x,更新AET
NET *p = pAET->next;
while (p)
{
p->x = p->x + p->dx;
p = p->next;
}
//更新后新AET先排序*************************************************************/
//断表排序,不再开辟空间
AET *tq = pAET;
p = pAET->next;
tq->next = NULL;
while (p)
{
while (tq->next && p->x >= tq->next->x)
tq = tq->next;
NET *s = p->next;
p->next = tq->next;
tq->next = p;
p = s;
tq = pAET;
}
//(改进算法)先从AET表中删除ymax==i的结点****************************************/
AET *q = pAET;
p = q->next;
while (p)
{
if (p->ymax == i)
{
q->next = p->next;
delete p;
p = q->next;
}
else
{
q = q->next;
p = q->next;
}
}
//将NET中的新点加入AET,并用插入法按X值递增排序**********************************/
p = pNET[i]->next;
q = pAET;
while (p)
{
while (q->next && p->x >= q->next->x)
q = q->next;
NET *s = p->next;
p->next = q->next;
q->next = p;
p = s;
q = pAET;
}
/******配对填充颜色***************************************************************/
p = pAET->next;
while (p && p->next)
{
for (float j = p->x; j <= p->next->x; j++)
glVertex2i(static_cast<int>(j), i);
p = p->next->next;//考虑端点情况
}
}
glEnd();
glFlush();
}
void init(int argc, char** argv)
{
glutInit(&argc, argv); //I初始化 GLUT.
glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB); //设置显示模式：单个缓存和使用RGB模型
glutInitWindowPosition(50, 100); //设置窗口的顶部和左边位置
glutInitWindowSize(400, 300); //设置窗口的高度和宽度
glutCreateWindow("Scan Program");
glClearColor(1.0, 1.0, 1.0, 0); //窗口背景颜色为白色
glMatrixMode(GL_PROJECTION);
gluOrtho2D(0, 600, 0, 450);
}
void myDisplay(void)
{
glClear(GL_COLOR_BUFFER_BIT);
glColor3f(0.0, 0.4, 0.2);
glPointSize(1);
glBegin(GL_POINTS);
PolyScan();
glEnd();
glFlush();
}
int main(int argc, char** argv)
{
init(argc, argv);
glutDisplayFunc(myDisplay); //图形的定义传递给我window.
glutMainLoop();
return 0;
}
#include "stdafx.h"
#include