struct 中定义方法例子

在头文件中定义

/// An axis aligned bounding box. struct b2AABB { /// Verify that the bounds are sorted. bool IsValid() const; /// Get the center of the AABB. b2Vec2 GetCenter() const { return 0.5f * (lowerBound + upperBound); } /// Get the extents of the AABB (half-widths). b2Vec2 GetExtents() const { return 0.5f * (upperBound - lowerBound); } /// Combine two AABBs into this one. void Combine(const b2AABB& aabb1, const b2AABB& aabb2) { lowerBound = b2Min(aabb1.lowerBound, aabb2.lowerBound); upperBound = b2Max(aabb1.upperBound, aabb2.upperBound); } /// Does this aabb contain the provided AABB. bool Contains(const b2AABB& aabb) const { bool result = true; result = result && lowerBound.x <= aabb.lowerBound.x; result = result && lowerBound.y <= aabb.lowerBound.y; result = result && aabb.upperBound.x <= upperBound.x; result = result && aabb.upperBound.y <= upperBound.y; return result; } bool RayCast(b2RayCastOutput* output, const b2RayCastInput& input) const; b2Vec2 lowerBound; ///< the lower vertex b2Vec2 upperBound; ///< the upper vertex }; inline bool b2AABB::IsValid() const { b2Vec2 d = upperBound - lowerBound; bool valid = d.x >= 0.0f && d.y >= 0.0f; valid = valid && lowerBound.IsValid() && upperBound.IsValid(); return valid; }

 

在cpp文件中

 

#include "b2aabb.h" // From Real-time Collision Detection, p179. bool b2AABB::RayCast(b2RayCastOutput* output, const b2RayCastInput& input) const { float32 tmin = -b2_maxFloat; float32 tmax = b2_maxFloat; b2Vec2 p = input.p1; b2Vec2 d = input.p2 - input.p1; b2Vec2 absD = b2Abs(d); b2Vec2 normal; for (int32 i = 0; i < 2; ++i) { if (absD(i) < b2_epsilon) { // Parallel. if (p(i) < lowerBound(i) || upperBound(i) < p(i)) { return false; } } else { float32 inv_d = 1.0f / d(i); float32 t1 = (lowerBound(i) - p(i)) * inv_d; float32 t2 = (upperBound(i) - p(i)) * inv_d; // Sign of the normal vector. float32 s = -1.0f; if (t1 > t2) { b2Swap(t1, t2); s = 1.0f; } // Push the min up if (t1 > tmin) { normal.SetZero(); normal(i) = s; tmin = t1; } // Pull the max down tmax = b2Min(tmax, t2); if (tmin > tmax) { return false; } } } // Does the ray start inside the box? // Does the ray intersect beyond the max fraction? if (tmin < 0.0f || input.maxFraction < tmin) { return false; } // Intersection. output->fraction = tmin; output->normal = normal; return true; }