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：