OpenGL（十七） 繪製折線圖、柱狀圖、餅圖
阿新 • • 發佈：2019-01-05
一、繪製折線圖
glutBitmapCharacter(GLUT_BITMAP_8_BY_13,label[j])函式可以繪製GLUT點陣圖字元，第一個引數是GLUT中指定的特定字形集，第二個引數是要寫入的單個字元；
#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); //繪製折線圖 glBegin(GL_LINE_STRIP); { for(int i=0;i<12;i++) { glVertex2i(20+i*50,dataValue[i]); } } glEnd(); //繪製標記點 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); //繪製序列 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); //回撥函式 glutReshapeFunc(ReshapFunction); glutMainLoop(); //持續顯示，當視窗改變會重新繪製圖形 return 0; }
折線圖：
二、柱狀圖
使用函式glRecti (GLint x1, GLint y1, GLint x2, GLint y2)可以方便的繪製一個填充的矩形區域，第一二個引數是矩形區域的左下角起點，第二三個引數是右上角頂點。
#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); //繪製序列 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); //回撥函式 glutMainLoop(); return 0; }
柱狀圖：
三、餅圖
#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); //回撥函式 glutMainLoop(); return 0; }
餅圖：
