OpenGL c++ 鼠标键盘交互 梁友栋算法 裁剪

#include <stdio.h> #include <stdlib.h> #include <math.h> #include <windows.h> #include <glut.h> #define N 1000 //maximum line numbers int ww=800,hh=600; // for display window width and height int line[N][4], k=0; //for line's endpoint coordinates and line number int flag=1,draw=1; int rx1,rx2,ry1,ry2; class Point2D { public: float x; float y; }; Point2D p1,p2,winMin,winMax; void Myinit(); void myMouse(int button,int state,int x,int y); void myMotion(int x,int y); void drawlines(); void Display(void); void Reshape(int w, int h); void Keyboard(unsigned char key, int x, int y); void drawbox(); void clipLine (Point2D winMin, Point2D winMax, Point2D p1, Point2D p2); int clipTest (float p, float q, float * u1, float * u2); void clipping(); void Myinit(void) { glClearColor(1.0,1.0,1.0,0.0); glLineWidth(1.0); glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); glEnable(GL_BLEND); glEnable(GL_POINT_SMOOTH); glHint(GL_POINT_SMOOTH_HINT, GL_NICEST); glEnable(GL_LINE_SMOOTH); glHint(GL_LINE_SMOOTH_HINT, GL_NICEST); glEnable(GL_POLYGON_SMOOTH); glHint(GL_POLYGON_SMOOTH_HINT, GL_NICEST); glPolygonMode(GL_FRONT_AND_BACK, GL_LINE); } //鼠标............................................................................................................................... void myMouse(int button,int state,int x,int y) { if (flag==1) { if(button==GLUT_LEFT_BUTTON&&state==GLUT_DOWN) { // get the line's start point line[k][0]=x; line[k][1]=hh-y; } if(button==GLUT_LEFT_BUTTON&&state==GLUT_UP) { // get the line's end point , count lines's number line[k][2]=x; line[k][3]=hh-y; k++; glutPostRedisplay(); } } if (flag==2) { if(button==GLUT_LEFT_BUTTON&&state==GLUT_DOWN) { // get the line's start point rx1=x; ry1=hh-y; } if(button==GLUT_LEFT_BUTTON&&state==GLUT_UP) { // get the line's end point , count lines's number rx2=x; ry2=hh-y; draw=2; glutPostRedisplay(); } } } //-----------------获得鼠标移动中的坐标----------------------------------------------------------- void myMotion(int x,int y) { if (flag==1) { line[k][2]=x; line[k][3]=hh-y; glutPostRedisplay(); } if (flag==2) { rx2=x; ry2=hh-y; glutPostRedisplay(); } } void drawlines() { glColor3f(0,0,1); for(int i=0;i<=k;i++) //******** { glBegin(GL_LINES); glVertex2f(line[i][0],line[i][1]); glVertex2f(line[i][2],line[i][3]); glEnd(); } } //画图--------------------------------------------------------------------------------------------------- void Display(void) { glClear(GL_COLOR_BUFFER_BIT); if (flag==1) drawlines(); if (flag==2) { if (draw==1) { drawlines(); drawbox(); } else { draw=1; clipping(); drawbox(); for (int i=0;i<=k;i++) { line[i][0]=0; line[i][1]=0; line[i][2]=0; line[i][3]=0; } k=0; rx1=0,rx2=0,ry1=0,ry2=0; } /*drawlines(); drawbox();*/ } glutSwapBuffers(); } //----------------------------------------------- void Reshape(int w, int h) { glMatrixMode(GL_PROJECTION); glLoadIdentity(); glViewport(0, 0, w, h); gluOrtho2D(0, w, 0, h); ww=w; hh=h; } int main(int argc, char** argv) { glutInit(&argc, argv); glutInitWindowSize(ww,hh); glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB); glutCreateWindow("Draw Lines by Mouse"); Myinit(); glutDisplayFunc(Display); glutKeyboardFunc(Keyboard); glutMouseFunc(myMouse); glutMotionFunc(myMotion); glutReshapeFunc(Reshape); glutMainLoop(); return 0; } void Keyboard(unsigned char key, int x, int y) { switch(key) { case '1': flag=1; break; case '2': flag=2; break; } glutPostRedisplay(); //参数修改后调用重画函数，屏幕图形将发生改变 } void drawbox() { glRectf(rx1,ry1,rx2,ry2); } void clipLine (Point2D winMin, Point2D winMax, Point2D p1, Point2D p2) { float u1 =0.0, u2 =1.0, dx= p2.x - p1.x, dy; if (clipTest(-dx, p1.x- winMin.x, &u1, &u2)) if (clipTest(dx, winMax.x-p1.x, &u1, &u2)) { dy = p2.y-p1.y; if (clipTest(-dy, p1.y-winMin.y, &u1, &u2)) if (clipTest(dy, winMax.y-p1.y, &u1, &u2)) { if (u2 < 1.0) { p2.x = p1.x + u2 * dx; p2.y = p1.y + u2 * dy; } if (u1 > 0.0) { p1.x += u1 * dx; p1.y += u1 * dy; } // line DDA (ROUND (p1 .x), ROUND(p1 .y), ROUND(p2 .x) , ROUND(p2 . y)); glBegin(GL_LINES); glVertex2f(p1.x,p1.y); glVertex2f(p2.x,p2.y); glEnd(); } } } int clipTest (float p, float q, float * u1, float * u2) { float r; int retVal = TRUE; if (p < 0.0) { r = q/p; if (r > *u2) retVal = FALSE; else if (r > *u1) *u1 = r; } else if (p >0.0) { r = q / p; if (r < *u1) retVal = FALSE; else if (r < *u2) *u2 = r; } else /* p = 0, so line is parallel to this clipping edge */ if (q < 0.0) /* Line is outside clipping edge */ retVal = FALSE; return (retVal) ; } void clipping() { if (rx1>=rx2) { winMin.x=rx2; winMax.x=rx1;} else { winMin.x=rx1; winMax.x=rx2;} if (ry1>=ry2) { winMin.y=ry2; winMax.y=ry1;} else { winMin.y=ry1; winMax.y=ry2;} for(int i=0;i<=k;i++) //******** { p1.x=line[i][0]; p1.y=line[i][1]; p2.x=line[i][2]; p2.y=line[i][3]; clipLine( winMin, winMax, p1, p2); } }