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Diffstat (limited to 'ThirdParty/Box2D/Collision/b2Distance.h')
| -rw-r--r-- | ThirdParty/Box2D/Collision/b2Distance.h | 166 |
1 files changed, 166 insertions, 0 deletions
diff --git a/ThirdParty/Box2D/Collision/b2Distance.h b/ThirdParty/Box2D/Collision/b2Distance.h new file mode 100644 index 0000000..d6eb985 --- /dev/null +++ b/ThirdParty/Box2D/Collision/b2Distance.h @@ -0,0 +1,166 @@ + +/* +* Copyright (c) 2006-2009 Erin Catto http://www.box2d.org +* +* This software is provided 'as-is', without any express or implied +* warranty. In no event will the authors be held liable for any damages +* arising from the use of this software. +* Permission is granted to anyone to use this software for any purpose, +* including commercial applications, and to alter it and redistribute it +* freely, subject to the following restrictions: +* 1. The origin of this software must not be misrepresented; you must not +* claim that you wrote the original software. If you use this software +* in a product, an acknowledgment in the product documentation would be +* appreciated but is not required. +* 2. Altered source versions must be plainly marked as such, and must not be +* misrepresented as being the original software. +* 3. This notice may not be removed or altered from any source distribution. +*/ + +#ifndef B2_DISTANCE_H +#define B2_DISTANCE_H + +#include "Box2D/Common/b2Math.h" + +class b2Shape; + +/// A distance proxy is used by the GJK algorithm. +/// It encapsulates any shape. +struct b2DistanceProxy +{ + b2DistanceProxy() : m_vertices(nullptr), m_count(0), m_radius(0.0f) {} + + /// Initialize the proxy using the given shape. The shape + /// must remain in scope while the proxy is in use. + void Set(const b2Shape* shape, int32 index); + + /// Initialize the proxy using a vertex cloud and radius. The vertices + /// must remain in scope while the proxy is in use. + void Set(const b2Vec2* vertices, int32 count, float32 radius); + + /// Get the supporting vertex index in the given direction. + int32 GetSupport(const b2Vec2& d) const; + + /// Get the supporting vertex in the given direction. + const b2Vec2& GetSupportVertex(const b2Vec2& d) const; + + /// Get the vertex count. + int32 GetVertexCount() const; + + /// Get a vertex by index. Used by b2Distance. + const b2Vec2& GetVertex(int32 index) const; + + b2Vec2 m_buffer[2]; + const b2Vec2* m_vertices; + int32 m_count; + float32 m_radius; +}; + +/// Used to warm start b2Distance. +/// Set count to zero on first call. +struct b2SimplexCache +{ + float32 metric; ///< length or area + uint16 count; + uint8 indexA[3]; ///< vertices on shape A + uint8 indexB[3]; ///< vertices on shape B +}; + +/// Input for b2Distance. +/// You have to option to use the shape radii +/// in the computation. Even +struct b2DistanceInput +{ + b2DistanceProxy proxyA; + b2DistanceProxy proxyB; + b2Transform transformA; + b2Transform transformB; + bool useRadii; +}; + +/// Output for b2Distance. +struct b2DistanceOutput +{ + b2Vec2 pointA; ///< closest point on shapeA + b2Vec2 pointB; ///< closest point on shapeB + float32 distance; + int32 iterations; ///< number of GJK iterations used +}; + +/// Compute the closest points between two shapes. Supports any combination of: +/// b2CircleShape, b2PolygonShape, b2EdgeShape. The simplex cache is input/output. +/// On the first call set b2SimplexCache.count to zero. +void b2Distance(b2DistanceOutput* output, + b2SimplexCache* cache, + const b2DistanceInput* input); + +/// Input parameters for b2ShapeCast +struct b2ShapeCastInput +{ + b2DistanceProxy proxyA; + b2DistanceProxy proxyB; + b2Transform transformA; + b2Transform transformB; + b2Vec2 translationB; +}; + +/// Output results for b2ShapeCast +struct b2ShapeCastOutput +{ + b2Vec2 point; + b2Vec2 normal; + float32 lambda; + int32 iterations; +}; + +/// Perform a linear shape cast of shape B moving and shape A fixed. Determines the hit point, normal, and translation fraction. +bool b2ShapeCast(b2ShapeCastOutput* output, const b2ShapeCastInput* input); + +////////////////////////////////////////////////////////////////////////// + +inline int32 b2DistanceProxy::GetVertexCount() const +{ + return m_count; +} + +inline const b2Vec2& b2DistanceProxy::GetVertex(int32 index) const +{ + b2Assert(0 <= index && index < m_count); + return m_vertices[index]; +} + +inline int32 b2DistanceProxy::GetSupport(const b2Vec2& d) const +{ + int32 bestIndex = 0; + float32 bestValue = b2Dot(m_vertices[0], d); + for (int32 i = 1; i < m_count; ++i) + { + float32 value = b2Dot(m_vertices[i], d); + if (value > bestValue) + { + bestIndex = i; + bestValue = value; + } + } + + return bestIndex; +} + +inline const b2Vec2& b2DistanceProxy::GetSupportVertex(const b2Vec2& d) const +{ + int32 bestIndex = 0; + float32 bestValue = b2Dot(m_vertices[0], d); + for (int32 i = 1; i < m_count; ++i) + { + float32 value = b2Dot(m_vertices[i], d); + if (value > bestValue) + { + bestIndex = i; + bestValue = value; + } + } + + return m_vertices[bestIndex]; +} + +#endif |