OpenGL（十七） 绘制折线图、柱状图、饼图

一、绘制折线图

glutBitmapCharacter(GLUT_BITMAP_8_BY_13,label[j])函数可以绘制GLUT位图字符，第一个参数是GLUT中指定的特定字形集，第二个参数是要写入的单个字符；

#include <glut.h> 

GLsizei windowWidth=600,windowHeight=600;
GLubyte label[36]={'O','n','e',  'T','w','o', 'T','h','r',  'F','o','u',
	'F','i','v',  'S','i','x',  'S','e','v',  'E','i','g',
	'N','i','e',  'T','e','n',  'E','l','e',  'T','w','e',};
GLint dataValue[12]={452,368,214,543,328,193,322,436,257,268,473,467};

void Init()
{
	glClearColor(1,1,1,1);
	glMatrixMode(GL_PROJECTION);
	gluOrtho2D(0,windowWidth,0,windowHeight);
}

void LineImage()
{
	glClear(GL_COLOR_BUFFER_BIT);
	glColor3f(0,0,1);
	glLineWidth(2);
	//绘制折线图
	glBegin(GL_LINE_STRIP);
	{
		for(int i=0;i<12;i++)
		{
			glVertex2i(20+i*50,dataValue[i]);
		}
	}
	glEnd();

	//绘制标记点
	glColor3f(1,0,0);
	for(int i=0;i<12;i++)
	{
		glRasterPos2i(15+i*50,dataValue[i]-5);
		glutBitmapCharacter(GLUT_BITMAP_8_BY_13,'*');
	}

	glColor3f(0,0,0);
	//绘制序列
	for(int i=0;i<12;i++)
	{
		glRasterPos2i(15+i*50,150);
		for(int j=i*3;j<i*3+3;j++)
		{
			glutBitmapCharacter(GLUT_BITMAP_8_BY_13,label[j]);
		}
	}
	glFlush();
}

void ReshapFunction(GLint x,GLint y)
{
	glClear(GL_COLOR_BUFFER_BIT);
}

int main(int argc, char *argv[])
{
	glutInit(&argc, argv);   //初始化GLUT
	glutInitDisplayMode(GLUT_RGB | GLUT_SINGLE);
	glutInitWindowPosition(500, 200);
	glutInitWindowSize(windowWidth, windowHeight);
	glutCreateWindow("OpenGL");
	Init();
	glutDisplayFunc(&LineImage);   //回调函数
	glutReshapeFunc(ReshapFunction);
	glutMainLoop();    //持续显示，当窗口改变会重新绘制图形
	return 0;
}  

折线图：

二、柱状图

使用函数glRecti (GLint x1, GLint y1, GLint x2, GLint y2)可以方便的绘制一个填充的矩形区域，第一二个参数是矩形区域的左下角起点，第二三个参数是右上角顶点。

#include <glut.h> 

GLsizei windowWidth=600,windowHeight=600;
GLubyte label[36]={'O','n','e',  'T','w','o', 'T','h','r',  'F','o','u',
	'F','i','v',  'S','i','x',  'S','e','v',  'E','i','g',
	'N','i','e',  'T','e','n',  'E','l','e',  'T','w','e',};
GLint dataValue[12]={452,368,214,543,328,193,322,436,257,268,473,467};

void Init()
{
	glClearColor(1,1,1,1);
	glMatrixMode(GL_PROJECTION);
	gluOrtho2D(0,windowWidth,0,windowHeight);
}

void LineImage()
{
	glClear(GL_COLOR_BUFFER_BIT);
	glColor3f(0,0,1);

	for(int i=0;i<12;i++)
	{
		glRecti(20+i*50,170,30+i*50,dataValue[i]);
	}

	glColor3f(0,0,0);
	//绘制序列
	for(int i=0;i<12;i++)
	{
		glRasterPos2i(15+i*50,150);
		for(int j=i*3;j<i*3+3;j++)
		{
			glutBitmapCharacter(GLUT_BITMAP_8_BY_13,label[j]);
		}
	}
	glFlush();
}

int main(int argc, char *argv[])
{
	glutInit(&argc, argv);   //初始化GLUT
	glutInitDisplayMode(GLUT_RGB | GLUT_SINGLE);
	glutInitWindowPosition(500, 200);
	glutInitWindowSize(windowWidth, windowHeight);
	glutCreateWindow("OpenGL");
	Init();
	glutDisplayFunc(&LineImage);   //回调函数
	glutMainLoop();
	return 0;
}  

柱状图：

三、饼图

#include <glut.h>
#include <stdlib.h>
#include <math.h>

GLsizei windowWidth=600,windowHeight=600;
GLint dataValue[12]={452,368,214,543,328,193,322,436,257,268,473,467};

void Init()
{
	glClearColor(1,1,1,1);
	glMatrixMode(GL_PROJECTION);
	gluOrtho2D(0,windowWidth,0,windowHeight);
}

void CircleImage()
{
	glClear(GL_COLOR_BUFFER_BIT);
	glColor3f(0,0,1);
	glPointSize(2);
	glBegin(GL_POINTS);
	{
		for(float i=0.0f;i<2*3.1415926f;i+=0.001)
		{
			glVertex2f((windowWidth/3)*cos(i)+windowWidth/2,(windowHeight/3)*sin(i)+windowHeight/2);
		}
	}
	glEnd();
	GLint totalNum=0;
	for(int i=0;i<12;i++)
	{
		totalNum+=dataValue[i];
	}

	GLfloat angleData[12];
	for(int i=0;i<12;i++)
	{
		angleData[i]=2*3.1415926f*(GLfloat)dataValue[i]/totalNum;

	}
	for(int j=1;j<12;j++)
	{
		angleData[j]+=angleData[j-1];
	}

	glColor3f(1,0,0);
	glLineWidth(2);

	glBegin(GL_LINES);
	{
		for(int i=0;i<12;i++)
		{
			glVertex2f(windowWidth/2,windowHeight/2);
			glVertex2f((windowWidth/3)*cos(angleData[i])+windowWidth/2,(windowHeight/3)*sin(angleData[i])+windowHeight/2);
		}
		glEnd();
		glFlush();
	}
}

int main(int argc, char *argv[])
{
	glutInit(&argc, argv);   //初始化GLUT
	glutInitDisplayMode(GLUT_RGB | GLUT_SINGLE);
	glutInitWindowPosition(500, 200);
	glutInitWindowSize(windowWidth, windowHeight);
	glutCreateWindow("OpenGL");
	Init();
	glutDisplayFunc(&CircleImage);   //回调函数
	glutMainLoop();
	return 0;
}  

饼图：