opengl 上的中点画线程序的实现

#include "math.h" #include <windows.h> #include <gl/glut.h> float point[2][2]; int k1=0,k2=0; void MiddleLine(float x0,float y0,float x1,float y1) { float a,b,d1,d2,d,x,y;float k; k=(y0-y1)/(x0-x1); if ((k>-1)&&(k<1)) { if (x0>x1) { float t[2]; t[0]=x0;t[1]=y0; x0=x1;y0=y1; x1=t[0];y1=t[1]; } x=x0;y=y0; a=y0-y1; b=x1-x0; glBegin(GL_POINTS); glVertex2f(x,y); glEnd(); if ((k<1)&&(k>=0)) { d=2*a+b;d1=2*a;d2=2*(a+b); while (x<=x1) { if (d<0) {x++;y++;d+=d2;} else {x++;d+=d1;} glBegin(GL_POINTS); glVertex2f(x,y); glEnd(); } } else if ((k<0)&&(k>-1)) { d=2*(a-0.5*b);d1=2*a;d2=2*(a-b); while (x<=x1) { if (d>0) { x++;y--;d+=d2;} else {x++;d+=d1;} glBegin(GL_POINTS); glVertex2f(x,y); glEnd(); } } } else{ if (y0>y1) { float t[2]; t[0]=x0;t[1]=y0; x0=x1;y0=y1; x1=t[0];y1=t[1]; } x=x0;y=y0; a=y0-y1; b=x1-x0; glBegin(GL_POINTS); glVertex2f(x,y); glEnd(); if (k>=1) { d=a+2*b;d1=2*b;d2=2*(a+b); while (y<=y1) { if (d>0) {y++;x++;d+=d2;} else {y++;d+=d1;} glBegin(GL_POINTS); glVertex2f(x,y); glEnd(); } } else if (k<=-1) { d=-a+2*b;d1=2*b;d2=2*(-a+b); while (y<=y1) { if (d<0) {y++;x--;d+=d2;} else {y++;d+=d1;} glBegin(GL_POINTS); glVertex2f(x,y); glEnd(); } } } } void RenderScene() { glClear(GL_COLOR_BUFFER_BIT); glLineWidth(1.0); glColor3f(0.0,1.0,0.0); if (k1==1) { MiddleLine(point[0][0],point[0][1],point[1][0],point[1][1]); k1=0; } glFlush(); glutSwapBuffers(); } void SetupRC() { glClearColor(0.0f,0.0f,0.0f,1.0f); } void Mouse(int button,int state,int x,int y) { y=600-y; if (button==GLUT_LEFT_BUTTON&&state==GLUT_DOWN) { k1=k2%2; point[k1][0]=x; point[k1][1]=y; if (k1==1) { glutPostRedisplay(); } k2++; } } void reshape(int w,int h) { glViewport(0,0,600,600); glMatrixMode(GL_PROJECTION); glLoadIdentity(); gluOrtho2D(0,600,0,600); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); } void main() { glutInitDisplayMode(GLUT_DOUBLE|GLUT_RGBA); glutInitWindowSize(600,600); glutCreateWindow("中点画线"); glutReshapeFunc(reshape); glutDisplayFunc(RenderScene); glutMouseFunc(Mouse); SetupRC(); glutMainLoop(); }