OpenGL编程轻松入门之像素操作.doc
OpenGL编程轻松入门之像素操作2006-05-23 08:35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*/void myInit(void)glClearColor(1.0,1.0,1.0,1.0);/*绘制彩色三角形*/void triangle(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();void myDisplay()int i;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();void myReshape(int w,int h)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();int main(int argc,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();return 0;·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。·void glCopyPixels（GLint x, Glint y, GLsizei width, GLsizei height, GLenum type）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*/GLubyte f_rasters12 = 0xc0,0xc0,0xc0,0xc0,0xc0,0xfc,0xfc,0xc0,0xc0,0xc0,0xff,0xff;/*字母I*/GLubyte i_rasters12 = 0xff,0xff,0x18,0x18,0x18,0x18,0x18,0x18,0x18,0x18,0xff,0xff;/*字母L*/GLubyte l_rasters12 = 0xff,0xff,0xc0,0xc0,0xc0,0xc0,0xc0,0xc0,0xc0,0xc0,0xc0,0xc0;/*字母E*/GLubyte e_rasters12 = 0xff,0xff,0xc0,0xc0,0xc0,0xff,0xff,0xc0,0xc0,0xc0,0xff,0xff;void myInit(void)glPixelStorei(GL_UNPACK_ALIGNMENT,1);/设置像素存储模式glClearColor(1.0,1.0,1.0,1.0);/设置背景为白色void myDisplay()glClear(GL_COLOR_BUFFER_BIT);glColor3f(0.0,0.0,0.0);/设置像素颜色为黑色glRasterPos2i(20,20);/为像素指定位置/*绘制位图*/glBitmap(8,12,0.0,0.0,14.0,0.0,f_rasters);glBitmap(8,12,0.0,0.0,14.0,0.0,i_rasters);glBitmap(8,12,0.0,0.0,14.0,0.0,l_rasters);glBitmap(8,12,0.0,0.0,14.0,0.0,e_rasters);glFlush();void myReshape(int w,int h)glViewport(0,0,(GLsizei)w,(GLsizei)h);glMatrixMode(GL_PROJECTION);glLoadIdentity();glOrtho(0,w,0,h,-1.0,1.0);glMatrixMode(GL_MODELVIEW);glLoadIdentity();int main(int argc,char * argv)/*初始化*/glutInit(&argc,argv);glutInitDisplayMode(GLUT_SINGLE|GLUT_RGB);glutInitWindowSize(500,400);glutInitWindowPosition(100,100);/*创建窗口*/glutCreateWindow(" BitMap");/*绘制图形*/myInit();glutReshapeFunc(myReshape);glutDisplayFunc(myDisplay);glutMainLoop();/进入GLUT事件处理循环return 0;·glBitmap（GLsizei width，GLsizei height，GLfloat xorig，GLfloat yorig，GLfloat xmove，GLfloat ymove，const GLubyte *bitmap）函数绘制一个位图。width，height分别指定位图图像的宽度和高度。xorig，yorig位图图像的原点位置。原点为位图的左下角。向右和向上为坐标轴的正向。xmove，ymove绘制完位图后x，y相对于当前光栅的位移。bitmap位图图像的地址。你可以改变此函数的参数，观察不同大小不同位置的效果
