梁友栋—柏世奇算法（以梁友栋和柏世奇（英语：Brian A. Barsky）的名字命名）是计算机图形学中的一个线段裁剪算法。梁友栋—柏世奇算法使用直线的参数方程和不等式组来描述线段和裁剪窗口的交集。求解出的交集将被用于获知线的哪些部分是应当绘制在屏幕上的。这一算法比科恩－苏泽兰算法（Cohen-Sutherland algorithm）要更加高效，梁友栋—柏世奇算法的基本思想是：在计算线段与裁剪窗交集之前做尽可能多的判断。

考虑直线的参数方程：

点在裁剪窗内，若

且

其可用4个不等式表达：

其中

计算最终线段：

// Liang--Barsky line-clipping algorithm#include<iostream>#include<graphics.h>#include<math.h>using namespace std;// this function gives the maximumfloat maxi(float arr,int n) {  float m = 0;  for (int i = 0; i < n; ++i)    if (m < arr)      m = arr;  return m;}// this function gives the minimumfloat mini(float arr, int n) {  float m = 1;  for (int i = 0; i < n; ++i)    if (m > arr)      m = arr;  return m;}void liang_barsky_clipper(float xmin, float ymin, float xmax, float ymax,                          float x1, float y1, float x2, float y2) {  // defining variables  float p1 = -(x2 - x1);  float p2 = -p1;  float p3 = -(y2 - y1);  float p4 = -p3;  float q1 = x1 - xmin;  float q2 = xmax - x1;  float q3 = y1 - ymin;  float q4 = ymax - y1;  float posarr, negarr;  int posind = 1, negind = 1;  posarr = 1;  negarr = 0;  rectangle(xmin, 467 - ymin, xmax, 467 - ymax); // drawing the clipping window  if ((p1 == 0 && q1 < 0) || (p3 == 0 && q3 < 0)) {      outtextxy(80, 80, "Line is parallel to clipping window!");      return;  }  if (p1 != 0) {    float r1 = q1 / p1;    float r2 = q2 / p2;    if (p1 < 0) {      negarr = r1; // for negative p1, add it to negative array      posarr = r2; // and add p2 to positive array    } else {      negarr = r2;      posarr = r1;    }  }  if (p3 != 0) {    float r3 = q3 / p3;    float r4 = q4 / p4;    if (p3 < 0) {      negarr = r3;      posarr = r4;    } else {      negarr = r4;      posarr = r3;    }  }  float xn1, yn1, xn2, yn2;  float rn1, rn2;  rn1 = maxi(negarr, negind); // maximum of negative array  rn2 = mini(posarr, posind); // minimum of positive array  if (rn1 > rn2)  { // reject    outtextxy(80, 80, "Line is outside the clipping window!");    return;  }  xn1 = x1 + p2 * rn1;  yn1 = y1 + p4 * rn1; // computing new points  xn2 = x1 + p2 * rn2;  yn2 = y1 + p4 * rn2;  setcolor(CYAN);  line(xn1, 467 - yn1, xn2, 467 - yn2); // the drawing the new line  setlinestyle(1, 1, 0);  line(x1, 467 - y1, xn1, 467 - yn1);  line(x2, 467 - y2, xn2, 467 - yn2);}int main() {  cout << "\nLiang-barsky line clipping";  cout << "\nThe system window outlay is: (0,0) at bottom left and (631, 467) at top right";  cout << "\nEnter the co-ordinates of the window(wxmin, wxmax, wymin, wymax):";  float xmin, xmax, ymin, ymax;  cin >> xmin >> ymin >> xmax >> ymax;  cout << "\nEnter the end points of the line (x1, y1) and (x2, y2):";  float x1, y1, x2, y2;  cin >> x1 >> y1 >> x2 >> y2;  int gd = DETECT, gm;  // using the winbgim library for C++, initializing the graphics mode  initgraph(&gd, &gm, "");  liang_barsky_clipper(xmin, ymin, xmax, ymax, x1, y1, x2, y2);  getch();  closegraph();}