图形图像--判断线段是否有交点

2009-07-27 20:09:28

// ########################## 判断线段是否有交点 ########################## //线段A向量 Ab(0.0f, 8.0f) Ae(8.0f, 0.0f)//线段B向量 Bb(0.0f, 0.0f) Be(8.0f, 8.0f)// 线段A的端点floatXAb = 0.0f, YAb = 8.0f,XAe = 8.0f,YAe = 0.0f;// 线段A的向量floatVXa = XAe - XAb,VYa = YAe - YAb;// 线段B的端点floatXBb = 0.0f,YBb = 0.0f,XBe = 3.9f,YBe = 3.9f;// 线段B的向量floatVXb = XBe - XBb,VYb = YBe - YBb;// Ae = Ab + s*Va// Be = Bb + t*Vb// 假设相交, 使 Ab + s*Va = Bb + t*Vb , 解出 s,t, 都符合[0,1]// 带入后可以求出相交点// s*Va - t*Vb = Bb - Ab;float b = (VXa * (-VYb)) - (VYa * (-VXb));float b1 = (XBb - XAb)*(-VYb)- (YBb-YAb)*(-VXb);float b2 = VXa*(YBb-YAb) - VYa*(XBb-XAb);float s=b1/b;float t=b2/b;if (s>=0.0f && s<=1.0f && t>=0.0f && t<=1.0f)return true;return false;