opengl 3种函数画线.rar_OPENGL画图_opengl 动态画线_opengl画直线

#include <glut.h> #include <math.h> #include <stdio.h> #include <Windows.h> const GLdouble Pi = 3.1415926536; BOOL LButtonDown = FALSE, LButtonUp = FALSE; int x_0, y_0, x_1, y_1; int X; float Y, k, dx, dy; int drawAlgo = 1; int a, b, dt1, dt2, d, ystp = 1; int iTag = 0; int tx, ty, inc1, inc2, curx, cury; void Swap(int &a, int &b) //交换函数 { int t; t = a; a = b; b = t; } void Initialize() // 初始化 { glClearColor(1.0, 1.0, 1.0, 1.0); glClear(GL_COLOR_BUFFER_BIT); glPointSize(2.0); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); gluOrtho2D(0, 600, 0, 600); } void mainMenu(int id) //主菜单 { drawAlgo = id; } void colorMenu(int id) //颜色菜单 { switch (id) { case 1: glColor3f(1.0, 0.0, 0.0); break; case 2: glColor3f(0.0, 1.0, 0.0); break; case 3: glColor3f(0.0, 0.0, 1.0); break; } } void weightMenu(int id) //线段粗细菜单 { glPointSize((float)id); } void dda(int x_1, int y_1,int x_0,int y_0) { Y = y_0; dx = x_1 - x_0; dy = y_1 - y_0; k = dy / dx; if (x_0 <= x_1) { for (X = x_0; X <= x_1; X++) { glBegin(GL_POINTS); glVertex2f(X, 600 - Y); glEnd(); glFlush(); Y += k; } } else { for (X = x_0; X >= x_1; X--) { glBegin(GL_POINTS); glVertex2f(X, 600 - Y); glEnd(); glFlush(); Y -= k; } } LButtonDown = FALSE; LButtonUp = FALSE; } void midfuc(int x_1, int y_1, int x_0, int y_0) { glBegin(GL_POINTS); // 画终点 glVertex2f(x_1, 600 - y_1); glEnd(); glFlush(); if (abs(x_1 - x_0) > abs(y_1 - y_0)) // 斜率的绝对值小于1的场合 { if (x_0 > x_1) // 如果是从右往左画，交换始点和终点 { X = x_0; x_0 = x_1; x_1 = X; Y = y_0; y_0 = y_1; y_1 = Y; } a = y_0 - y_1; b = x_1 - x_0; // 此时b一定为正 if (a > 0) // 如果斜率为负 { a = -a; ystp = -1; } else // 如果斜率不为负 { ystp = 1; } d = (a << 1) + b; // 判别式 dt1 = a << 1; dt2 = (a + b) << 1; X = x_0; Y = y_0; glBegin(GL_POINTS); // 画始点 glVertex2f(X, 600 - Y); glEnd(); glFlush(); while (X < x_1) // 开始画线（始点和终点之间的点） { if (d < 0) { X++; Y += ystp; d += dt2; } else { X++; d += dt1; } glBegin(GL_POINTS); glVertex2f(X, 600 - Y); glEnd(); glFlush(); } LButtonDown = FALSE; LButtonUp = FALSE; } else // 斜率绝对值大于等于1的场合 { if (y_0 > y_1) // 如果从下往上画，交换始点和终点 { X = x_0; x_0 = x_1; x_1 = X; Y = y_0; y_0 = y_1; y_1 = Y; } a = x_0 - x_1; b = y_1 - y_0; // b一定大于0 if (a > 0) // 如果从右往左画 { a = -a; ystp = -1; } else // 如果从左往右画 { ystp = 1; } d = (a << 1) + b; // 判别式 dt1 = a << 1; dt2 = (a + b) << 1; X = x_0; Y = y_0; glBegin(GL_POINTS); glVertex2f(X, 600 - Y); glEnd(); glFlush(); while (Y < y_1) { if (d < 0) { Y++; X += ystp; d += dt2; } else { Y++; d += dt1; } glBegin(GL_POINTS); glVertex2f(X, 600 - Y); glEnd(); glFlush(); } } LButtonDown = FALSE; // 重置鼠标点击 LButtonUp = FALSE; } void Bresenham(int x_1, int y_1, int x_0, int y_0) { glBegin(GL_POINTS); // 画终点 glVertex2f(x_1, 600 - y_1); glEnd(); glFlush(); if (x_0 == x_1 && y_0 == y_1) // 始点和终点重合时，结束画线 { return; } dx = abs(x_1 - x_0); dy = abs(y_1 - y_0); if (dx < dy) // 如果斜率绝对值大于1 { iTag = 1; // iTag标记画线斜率是否大于1，如果是就变成其反函数 Swap(x_1, y_1); Swap(x_0, y_0); int temp = dx; dx = dy; dy = temp; } tx = (x_1 - x_0) > 0 ? 1 : -1; // 如果从左往右画，tx为1，否则是-1 ty = (y_1 - y_0) > 0 ? 1 : -1; // 如果从上往下画，ty为1，否则是-1 curx = x_0; // 记录变换后的始点 cury = y_0; inc1 = 2 * dy; // 当判别式小于等于0时，d的增量 inc2 = 2 * (dy - dx); // 当判别式大于等于0时，d的增量 d = inc1 - dx; // 始点的判别量d0 while (curx != x_1) { curx += tx; // 横坐标步进1或-1 if (d < 0) { d += inc1; } else { cury += ty; d += inc2; } if (iTag) // 斜率大于1的场合 { glBegin(GL_POINTS); glVertex2f(cury, 600 - curx); glEnd(); glFlush(); } else // 斜率小于等于1的场合 { glBegin(GL_POINTS); glVertex2f(curx, 600 - cury); glEnd(); glFlush(); } } LButtonDown = FALSE; // 重置鼠标单击和iTag LButtonUp = FALSE; iTag = 0; } void myMouse(int button, int state, int x, int y) { if (button == GLUT_LEFT_BUTTON && state == GLUT_DOWN) // 读取始点坐标（左键按下） { LButtonDown = TRUE; x_0 = x; y_0 = y; } if (button == GLUT_LEFT_BUTTON && state == GLUT_UP) // 读取终点坐标（左键松开） { LButtonUp = TRUE; x_1 = x; y_1 = y; } if (LButtonDown && LButtonUp) { if (drawAlgo == 1) // DDA算法 { dda(x_1, y_1, x_0, y_0); } else if (drawAlgo == 2) // 中点画线法 { midfuc(x_1, y_1, x_0, y_0); } else // Bresenham算法 { Bresenham(x_1, y_1, x_0, y_0); } } } void myDisplay(void) { int i; glBegin(GL_TRIANGLE_FAN); glColor3f(1.0f, 1.0f, 1.0f); glVertex2f(0.0f, 0.0f); for (i = 0; i <= 8; ++i) { glColor3f(i & 0x04, i & 0x02, i & 0x01); glVertex2f(cos(i*Pi / 4), sin(i*Pi / 4)); } glEnd(); glFlush(); } int main(int argc, char *argv[]) { glutInit(&argc, argv); // 对GLUT进行初始化，这个函数必须在其它的GLUT使用之前调用一次 glutInitDisplayMode(GLUT_RGB | GLUT_SINGLE); // 设置显示方式(RGB颜色，单缓冲) glutInitWindowSize(600, 600); // 设置窗口的尺寸 glutInitWindowPosition(400, 150); // 设置窗口在屏幕中的位置 glutCreateWindow("OpenGL"); // 根据前面设置的信息创建窗口。参数将被作为窗口的标题 Initialize(); glutDisplayFunc(&myDisplay); glutMouseFunc(&myMouse); int ColorMenu = glutCreateMenu(colorMenu); //颜色菜单创建 glutAddMenuEntry("红", 1); glutAddMenuEntry("绿", 2); glutAddMenuEntry("蓝", 3); int WeightMenu = glutCreateMenu(weightMenu); //线段粗细菜单创建 glutAddMenuEntry("1px", 1); glutAddMenuEntry("2px(默认)", 2); glutAddMenuEntry("3px", 3); glutAddMenuEntry("4px", 4); glutAddMenuEntry("5px", 5); glutAddMenuEntry("6px", 6); glutAddMenuEntry("7px", 7); glutAddMenuEntry("8px", 8); glutAddMenuEntry("9px", 9); glutAddMenuEntry("10px", 10); glutCreateMenu(mainMenu); //创建主菜单，并使用回调函数mainMenu glutAddMenuEntry("DDA(默认)", 1); //加入菜单项 glutAddMenuEntry("中点画线法", 2); glutAddMenuEntry("Bresenham算法", 3); glutAddSubMenu("画线颜色", ColorMenu); glutAddSubMenu("画线粗细", WeightMenu); glutAttachMenu(GLUT_RIGHT_BUTTON); //把菜单与鼠标右键相关联，则点击右键会出现菜单 glutMainLoop(); // 显示窗口，并且等待窗口关闭后才会返回 return 0; }