OpengGL 仿射变换Demo

                                                 OpengGL 仿射变换Demo

 

download here:

http://download.youkuaiyun.com/user/rorger

 

 

//TransformOpenGL.cpp //rorger, 2011 #include "nrglbase.h" #include "nrdraw.h" #include "nrmath.h" #include "glut.h" #include "math.h" void drawRect(NRHomogeneousPoint2D rect[]) { glBegin(GL_LINE_LOOP); for (int i=0;i<4;i++) { glVertex2f(rect[i].x,rect[i].y); } glEnd(); } void doTransform2D(NRHomogeneousPoint2D rect[],NRTranslateTransform2D transform) { for (int i=0;i<4;i++) { rect[i]=transform*rect[i]; } } void doTransform2D(NRHomogeneousPoint2D rect[],NRScaleTransform2D transform) { for (int i=0;i<4;i++) { rect[i]=transform*rect[i]; } } void doTransform2D(NRHomogeneousPoint2D rect[],NRRotateTransform2D transform) { for (int i=0;i<4;i++) { rect[i]=transform*rect[i]; } } void doTransform2D(NRHomogeneousPoint2D rect[],NRClipTransform2D transform) { for (int i=0;i<4;i++) { rect[i]=transform*rect[i]; } } void doTransform2D(NRHomogeneousPoint2D rect[],NRCompositeTransform2D transform) { for (int i=0;i<4;i++) { rect[i]=transform*rect[i]; } } void initRect(NRHomogeneousPoint2D rect[]) { rect[0].x=0; rect[0].y=0; rect[1].x=4; rect[1].y=0; rect[2].x=4; rect[2].y=3; rect[3].x=0; rect[3].y=3; } void testTransform() { double pi = acos(-1.0); NRHomogeneousPoint2D rect[4] ; initRect(rect); drawRect(rect); //test translate NRTranslateTransform2D translateTransform; translateTransform.Translate(5,4); doTransform2D(rect,translateTransform); glColor3f(0.5,0.5,0.3); drawRect(rect); //testScale initRect(rect); NRScaleTransform2D scaleTransform ; scaleTransform.Scale(0.5,0.4); doTransform2D(rect,scaleTransform); glColor3f(1.0,0.5,0.5); drawRect(rect); //testRotate initRect(rect); NRRotateTransform2D rotateTransform ; rotateTransform.Rotate(pi/3); //为什么看起来是平行四边形? doTransform2D(rect,rotateTransform); glColor3f(0.5,0.2,0.7); drawRect(rect); //testClip initRect(rect); NRClipTransform2D clipTransform ; clipTransform.Clip(0.0,0.3); //在x方向上剪切 doTransform2D(rect,clipTransform); glColor3f(0.2,0.5,0.7); drawRect(rect); initRect(rect); translateTransform.Translate(0,4); doTransform2D(rect,translateTransform); NRClipTransform2D clipTransform2 ; clipTransform2.Clip(0.3,0.0); //在y方向上剪切 doTransform2D(rect,clipTransform2); glColor4f(0.2,0.3,0.4,0.0); drawRect(rect); //testComposite //也许效果和你想的有些误差，但是这是基于原点进行旋转和缩放的,所以不必惊讶 NRCompositeTransform2D compositeTransform ; compositeTransform.AddTransform(translateTransform); compositeTransform.AddTransform(rotateTransform); compositeTransform.AddTransform(scaleTransform); initRect(rect); doTransform2D(rect,compositeTransform); glColor3f(0.3,0.5,0.3); drawRect(rect); } void myDisplay(void) { glClear(GL_COLOR_BUFFER_BIT); NRDrawCoordinate(); glColor3f(0.0f, 1.0f, 0.0f); testTransform(); glFlush(); } void myInit(void) { glClearColor(0.0, 0.0, 0.0, 0.0); glColor3f(0.0f, 1.0f, 0.0f); glPointSize(4.0); glMatrixMode(GL_PROJECTION); glLoadIdentity(); gluOrtho2D(-5, 15, -5, 15); glLineWidth(2.0); } int main(int argc,char** argv) { glutInit(&argc, argv); glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB); glutInitWindowSize(640,480); glutInitWindowPosition(100,150); glutCreateWindow("LineInterSectoin"); glutDisplayFunc(myDisplay); myInit( ); glutMainLoop( ); }

效果：

 

 

ps: date:4/21/2012 12:02

关于为什么矩形旋转后是平行四边形的问题，这是由于窗口设置拉伸的问题；

只要把窗口设置为480*480，效果马上就出来了；