OpenGL编程轻松入门之像素操作2006-05-2308:35作者：黄燕出处：天极开发责任编辑：方舟本节讲解像素操作。例14：本例在窗口绘制一个三角形，然后利用glCopyPixel函数拷贝了五次该图形，并将这五个三角形放置在窗口的不同位置。#include<stdlib.h>#include<GL/glut.h>/*设置背景色*/voidmyInit(void){glClearColor(1.0,1.0,1.0,1.0);}/*绘制彩色三角形*/voidtriangle(void){glBegin(GL_TRIANGLES);glColor3f(1.0,1.0,0.0);glVertex2f(10.0,10.0);glColor3f(0.0,0.3,1.0);glVertex2f(20.0,30.0);glColor3f(1.0,0.0,0.0);glVertex2f(30.0,10.0);glEnd();}voidmyDisplay(){inti;glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);glPushMatrix();glTranslatef(10.0,100.0,0.0);triangle();glPopMatrix();glPushMatrix();for(i=0;i<5;i++){glRasterPos2i(20+i*30,10+i*5);//为像素操作指定光栅位置glCopyPixels(50,200,500,500,GL_COLOR);//在缓存中拷贝像素}glPopMatrix();glFlush();}voidmyReshape(intw,inth){glViewport(0,0,(GLsizei)w,(GLsizei)h);glMatrixMode(GL_PROJECTION);glLoadIdentity();if(w<=h)gluOrtho2D(0.0,150,0.0,150.0*(GLfloat)h/(GLfloat)w);elsegluOrtho2D(0.0,150*(GLfloat)w/(GLfloat)h,0.0,150.0);glMatrixMode(GL_MODELVIEW);glLoadIdentity();}intmain(intargc,char**argv){glutInit(&argc,argv);glutInitDisplayMode(GLUT_SINGLE|GLUT_RGB|GLUT_DEPTH);glutInitWindowSize(500,400);glutInitWindowPosition(100,100);glutCreateWindow("copy");myInit();glutReshapeFunc(myReshape);glutDisplayFunc(myDisplay);glutMainLoop();return0;}·glRasterPos在像素操作中指定光栅位置。同样后面的数字表示坐标维数，2表示坐标为x、y，3表示、，y、z。数字后面的字母表示参数类型。最后带V表示参数为指针。·voidglCopyPixels（GLintx,Glinty,GLsizeiwidth,GLsizeiheight,GLenumtype）函数将像素拷贝到缓存中。x，y指定被拷贝像素的右下角坐标。width，heigth指定被拷贝像素矩形区域的大小。type指定拷贝数值的类型。值为颜色、深度或膜板值。本例中为颜色。例15：此例在窗口左下角写单词FILE。#include<stdlib.h>#include<GL/glut.h>/*字母F*/GLubytef_rasters[12]={0xc0,0xc0,0xc0,0xc0,0xc0,0xfc,0xfc,0xc0,0xc0,0xc0,0xff,0xff};/*字母I*/GLubytei_rasters[12]={0xff,0xff,0x18,0x18,0x18,0x18,0x18,0x18,0x18,0x18,0xff,0xff};/*字母L*/GLubytel_rasters[12]={0xff,0xff,0xc0,0xc0,0xc0,0xc0,0xc0,0xc0,0xc0,0xc0,0xc0,0xc0};/*字母E*/GLubytee_rasters[12]={0xff,0xff,0xc0,0xc0,0xc0,0xff,0xff,0xc0,0xc0,0xc0,0xff,0xff};voidmyInit(void){glPixelStorei(GL_UNPACK_ALIGNMENT,1);//设置像素存储模式glClearColor(1.0,1.0,1.0,1.0)