opengl下的bresenham和dda直线算法实现（键盘输入点）

#include "stdio.h" #include "iostream.h" #include <GL/glut.h> #include <math.h> float a, b, c, d; int flag; int xStart=0, yStart=0, xEnd=0, yEnd=0; int pointSize=2; void dda(float x1,float y1,float x2,float y2) { float x,y,k; int d=1; int i; k=abs(x2-x1); if(abs(y2-y1)>k) { k=abs(y2-y1); d=-1; } x=x1; y=y1; for(i=0;i<=k;i++) { glPointSize(10.0); glBegin(GL_POINTS); if(d==1) glVertex2f(x,int(y+0.5)); else glVertex2f(int(x+0.5),y); glEnd(); x=x+(x2-x1)/k; y=y+(y2-y1)/k; } } void bres(float x1,float y1,float x2,float y2) { float x,y,dx,dy,f,temp; int s1,s2,interchange,i; x=x1; y=y1; dx=abs(x2-x1); dy=abs(y2-y1); if(x2-x1>=0) s1=1; else s1=-1; if(y2-y1>=0) s2=1; else s2=-1; if(dy>dx) { temp=dx; dx=dy; dy=temp; interchange=1; } else interchange=0; f=2*dy-dx; for(i=0;i<=dx;i++) { glPointSize(10.0); glBegin(GL_POINTS); if(f>0) { if(interchange==1) x=x+s1; else y=y+s2; glVertex2f(x,y); glEnd(); f=f-2*dx; } if(interchange=1) y=y+s2; else x=x+s1; glVertex2f(x,y); glEnd(); f=f+2*dy; } } //鼠标响应函数 void mouse(int button, int state, int x, int y) { if(state==GLUT_DOWN) { switch(button) { case GLUT_LEFT_BUTTON: xStart = x; yStart = 300-y; cout<<"L("<<xStart<<","<<yStart<<")"<<endl; break; case GLUT_RIGHT_BUTTON: xEnd = x; yEnd = 300-y; cout<<"R("<<xEnd<<","<<yEnd<<")"<<endl; break; case GLUT_MIDDLE_BUTTON: break; } } glClear(GL_COLOR_BUFFER_BIT); } //点击鼠标时水平直线（dy=0）的响应函数 void lineBresPlane(void) { int x, y, xx, yy; if( xStart>xEnd ) { x = xEnd; y = yEnd; xx = xStart; yy = yStart; } else { x = xStart; y = yStart; xx = xEnd; yy = yEnd; } glBegin(GL_POINTS); glVertex2i(x, y); glEnd(); while(x<xx) { x += (pointSize/2); glBegin(GL_POINTS); glVertex2i(x, y); glEnd(); } } //点击鼠标时竖直直线（dx=0）的响应函数 void lineBresApeak(void) { int x, y, xx, yy; if( yStart>yEnd ) { y = yEnd; x = xEnd; yy = yStart; xx = xStart; } else { y = yStart; x = xStart; yy = yEnd; xx = xEnd; } glBegin(GL_POINTS); glVertex2i(x, y); glEnd(); while(y<yy) { y += (pointSize/2); glBegin(GL_POINTS); glVertex2i(x, y); glEnd(); } } //点击鼠标时dx=dy时的响应函数 void lineBresDiagonal(void) { int x, y, xx, yy; if( xStart>xEnd ) { x = xEnd; y = yEnd; xx = xStart; yy = yStart; } else { x = xStart; y = yStart; xx = xEnd; yy = yEnd; } glBegin(GL_POINTS); glVertex2i(x, y); glEnd(); bool flag = false; if(yy>y) flag = true; while(x<xx) { x += (pointSize/2); if(flag) y += (pointSize/2); else y -= (pointSize/2); glBegin(GL_POINTS); glVertex2i(x, y); glEnd(); } } //点击鼠标时dx>dy时的响应函数 void lineBresXbig(void) { int dx = fabs(xEnd - xStart), dy = fabs(yEnd - yStart); int p = 2*dy - dx; int twoDy = 2*dy, twoDyMinusDx = 2*(dy-dx); int x, y, xx, yy; if( xStart>xEnd ) { x = xEnd; y = yEnd; xx = xStart; yy = yStart; } else { x = xStart; y = yStart; xx = xEnd; yy = yEnd; } glBegin(GL_POINTS); glVertex2i(x, y); glEnd(); bool flag = false; if(yy>y) flag = true; while(x<xx) { x += (pointSize/2); if(p<0) p += twoDy; else { if(flag) y += (pointSize/2); else y -= (pointSize/2); p += twoDyMinusDx; } glBegin(GL_POINTS); glVertex2i(x, y); glEnd(); } } //点击鼠标时dx<dy时的响应函数 void lineBresYbig(void) { int dx = fabs(xEnd - xStart), dy = fabs(yEnd - yStart); int p = 2*dx - dy; int twoDx = 2*dx, twoDxMinusDy = 2*(dx-dy); int x, y, xx, yy; if( yStart>yEnd ) { y = yEnd; x = xEnd; yy = yStart; xx = xStart; } else { y = yStart; x = xStart; yy = yEnd; xx = xEnd; } glBegin(GL_POINTS); glVertex2i(x, y); glEnd(); bool flag = false; if(xx>x) flag = true; while(y<yy) { y += (pointSize/2); if(p<0) p += twoDx; else { if(flag) x += (pointSize/2); else x -= (pointSize/2); p += twoDxMinusDy; } glBegin(GL_POINTS); glVertex2i(x, y); glEnd(); } } //鼠标取点时Bresenham算法实现 void Bresenham(void) { int dx = fabs(xEnd - xStart), dy = fabs(yEnd - yStart); if(dx==0) lineBresApeak(); else if(dy==0) lineBresPlane(); else if(dx==dy) lineBresDiagonal(); else if(dx>dy) lineBresXbig(); else lineBresYbig(); } void renderScene(void) { glClear(GL_COLOR_BUFFER_BIT); //刷新背景 glLoadIdentity(); //两坐标系重合或者说坐标原点移到窗口中心 glClearColor(0.0f,1.0f,0.0f,0.0f); int i,j; for(i=-20;i<=20;i++) for(j=-20;j<=20;j++) { glBegin(GL_LINES); glColor3f(0.75,0.75,0.75); glVertex2f(i,-20.0); glVertex2f(i,20.0); glVertex2f(-20,j); glVertex2f(20,j); glEnd(); } glBegin(GL_LINES); glColor3f(0.0,0.0,0.0); glVertex2f(0.0,-20.0); glVertex2f(0.0,20.0); glVertex2f(-20.0,0.0); glVertex2f(20.0,0.0); // glColor3f(1.0,0.0,0.0); // glEvalCoord2f(0.0,0.0); glEnd(); /*draw points*/ glPointSize(10.0); glBegin(GL_POINTS); if(flag==2) { glColor3f(1.0f, 1.0f, 1.0f); bres(a,b,c,d); } else if(flag==1) { glColor3f(1.0f, 0.0f, 0.0f); dda(a,b,c,d); } else { glColor3f(0.25f, 0.25f, 0.25f); Bresenham(); } // glEvalPoint2(0.0,0.0); // glVertex3f(0.0,0.0,0.0); // glVertex3f(0.0,0.0,0.0); glEnd(); glFlush(); } //使用鼠标时屏幕初始化 void init(void) { glClearColor(0.0, 1.0, 0.0, 0.0); glClear(GL_COLOR_BUFFER_BIT); glColor3f(1.0, 0.0, 0.0); glPointSize(pointSize); glMatrixMode(GL_PROJECTION); glLoadIdentity(); gluOrtho2D(0.0, 400.0, 0.0, 300.0); } //使用鼠标时刷新窗口 void reshape(int w, int h) { glutPostRedisplay(); glViewport(0, 0, w, h); } void ChangeSize(GLsizei w, GLsizei h)//设置窗口 { // Prevent a divide by zero GLfloat nRange = 20.0f; if(h == 0) h = 1; glViewport(0, 0, w, h);/*定义了视口和视口坐标。第一、二个参数是视口左下角的像素坐标， 第三、四个参数是视口的宽度和高度。*/ glMatrixMode(GL_PROJECTION);//从人眼坐标系转到剪裁坐标系 glLoadIdentity(); // 平行投影 (left, right, bottom, top, near, far) if (w <= h) glOrtho (-nRange, nRange, -nRange*h/w, nRange*h/w, -nRange*2.0f, nRange*2.0f); else glOrtho (-nRange*w/h, nRange*w/h, -nRange, nRange, -nRange*2.0f, nRange*2.0f); glMatrixMode(GL_MODELVIEW);//从实体坐标系转到人眼坐标系 glLoadIdentity(); } int main(int argc, char* argv[]) { printf("请选择算法 1--add 2-bresenham 3-鼠标取点\n"); scanf("%d",&flag); if (flag==3) { cout<<"输入显示的方格大小(2的倍数): "; cin>>pointSize; cout<<"单击鼠标左键确定第一个端点，单击右键确定第二个端点。"<<endl; cout<<"\n\n"; glutInit(&argc, argv); glutInitDisplayMode(GLUT_SINGLE|GLUT_RGB); glutInitWindowPosition(20, 20); glutInitWindowSize(400, 300); glutCreateWindow("Bresenham"); init(); glutMouseFunc(mouse); glutReshapeFunc(reshape); glutDisplayFunc(Bresenham); glutIdleFunc(Bresenham); glutMainLoop(); } else { printf("请输入点的坐标:x[-20,20],y[-20,20]\n"); scanf("%f %f %f %f",&a,&b,&c,&d); glutInit(&argc, argv); glutInitDisplayMode(GLUT_DEPTH | GLUT_SINGLE | GLUT_RGBA); glutInitWindowSize(600, 600); glutInitWi