openGL学习笔记3

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三、视口变换

相关函数

glLoadIdentity();

将当前的用户坐标系的原点移到了屏幕中心：类似于一个复位操作。

void gluLookAt(GLdouble eyex,GLdouble eyey,GLdouble eyez,GLdouble centerx,GLdouble centery,GLdouble centerz,GLdouble upx,GLdouble upy,GLdouble upz)

视点转换

glScalef(x,y,z)

对模型进行xyz方向上的压缩拉伸

glViewport(0,0,GLsizei(w),GLsizei(h))

以左下角为原点选择绘图区域

glMatrixMode(GL_PROJECTION)

设置当前操作的矩阵 GL_PROJECTION为投影矩阵 GL_MODELVIEW 模型视图矩阵

#include<Windows.h>#include<gl\glut.h>#pragma comment(linker, "/subsystem:\"windows\" /entry:\"mainCRTStartup\"")void init(void){glClearColor(0.0,0.0,0.0,0.0);glShadeModel(GL_FLAT);}void disply(){glClear(GL_COLOR_BUFFER_BIT);glColor3f(1.0,1.0,1.0);glLoadIdentity();//坐标系复位gluLookAt(0.0,0.0,5.0,0.0,0.0,0.0,0.0,1.0,0.0);//视点转换 glScalef(1.0,1.0,1.0);//模型在Y方向拉伸为原来的2倍glutWireCube(1.0);//绘制边长为1的线框立方体glFlush();}void reshape(int w,int h){glViewport(0,0,GLsizei(w),GLsizei(h));//以左下角为原点选择绘图区域glMatrixMode(GL_PROJECTION);//指定当前操作矩阵为投影矩阵glLoadIdentity();//glFrustum(-1.0,1.0,-1.0,1.0,1.5,20.0);//把当前矩阵转变成透视矩阵//gluPerspective(30,1.0,1.5,50);glOrtho(-1.0,1.0,-1.0,1.0,1.5,20);glMatrixMode(GL_MODELVIEW);//对模型视图矩阵进行操作 }int main(int argc, char** argv){ glutInit(&argc,argv); glutInitDisplayMode(GLUT_SINGLE|GLUT_RGB);//指定显示模式 glutInitWindowSize(500,500);//指定窗口大小 glutInitWindowPosition(100,100);//指定窗口左上角位置 glutCreateWindow("OpenGL");//创建窗口标题为OpenGL的窗口 init(); glutDisplayFunc(disply);  glutReshapeFunc(reshape); glutMainLoop(); return 0;}

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