1 files changed, 459 insertions, 0 deletions
diff --git a/Client/ThirdParty/Box2D/src/collision/b2_polygon_shape.cpp b/Client/ThirdParty/Box2D/src/collision/b2_polygon_shape.cpp
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+++ b/Client/ThirdParty/Box2D/src/collision/b2_polygon_shape.cpp
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+// MIT License
+
+// Copyright (c) 2019 Erin Catto
+
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+#include "box2d/b2_polygon_shape.h"
+#include "box2d/b2_block_allocator.h"
+
+#include <new>
+
+b2Shape* b2PolygonShape::Clone(b2BlockAllocator* allocator) const
+{
+	void* mem = allocator->Allocate(sizeof(b2PolygonShape));
+	b2PolygonShape* clone = new (mem) b2PolygonShape;
+	*clone = *this;
+	return clone;
+}
+
+void b2PolygonShape::SetAsBox(float hx, float hy)
+{
+	m_count = 4;
+	m_vertices[0].Set(-hx, -hy);
+	m_vertices[1].Set( hx, -hy);
+	m_vertices[2].Set( hx,  hy);
+	m_vertices[3].Set(-hx,  hy);
+	m_normals[0].Set(0.0f, -1.0f);
+	m_normals[1].Set(1.0f, 0.0f);
+	m_normals[2].Set(0.0f, 1.0f);
+	m_normals[3].Set(-1.0f, 0.0f);
+	m_centroid.SetZero();
+}
+
+void b2PolygonShape::SetAsBox(float hx, float hy, const b2Vec2& center, float angle)
+{
+	m_count = 4;
+	m_vertices[0].Set(-hx, -hy);
+	m_vertices[1].Set( hx, -hy);
+	m_vertices[2].Set( hx,  hy);
+	m_vertices[3].Set(-hx,  hy);
+	m_normals[0].Set(0.0f, -1.0f);
+	m_normals[1].Set(1.0f, 0.0f);
+	m_normals[2].Set(0.0f, 1.0f);
+	m_normals[3].Set(-1.0f, 0.0f);
+	m_centroid = center;
+
+	b2Transform xf;
+	xf.p = center;
+	xf.q.Set(angle);
+
+	// Transform vertices and normals.
+	for (int32 i = 0; i < m_count; ++i)
+	{
+		m_vertices[i] = b2Mul(xf, m_vertices[i]);
+		m_normals[i] = b2Mul(xf.q, m_normals[i]);
+	}
+}
+
+int32 b2PolygonShape::GetChildCount() const
+{
+	return 1;
+}
+
+static b2Vec2 ComputeCentroid(const b2Vec2* vs, int32 count)
+{
+	b2Assert(count >= 3);
+
+	b2Vec2 c(0.0f, 0.0f);
+	float area = 0.0f;
+
+	// Get a reference point for forming triangles.
+	// Use the first vertex to reduce round-off errors.
+	b2Vec2 s = vs[0];
+
+	const float inv3 = 1.0f / 3.0f;
+
+	for (int32 i = 0; i < count; ++i)
+	{
+		// Triangle vertices.
+		b2Vec2 p1 = vs[0] - s;
+		b2Vec2 p2 = vs[i] - s;
+		b2Vec2 p3 = i + 1 < count ? vs[i+1] - s : vs[0] - s;
+
+		b2Vec2 e1 = p2 - p1;
+		b2Vec2 e2 = p3 - p1;
+
+		float D = b2Cross(e1, e2);
+
+		float triangleArea = 0.5f * D;
+		area += triangleArea;
+
+		// Area weighted centroid
+		c += triangleArea * inv3 * (p1 + p2 + p3);
+	}
+
+	// Centroid
+	b2Assert(area > b2_epsilon);
+	c = (1.0f / area) * c + s;
+	return c;
+}
+
+void b2PolygonShape::Set(const b2Vec2* vertices, int32 count)
+{
+	b2Assert(3 <= count && count <= b2_maxPolygonVertices);
+	if (count < 3)
+	{
+		SetAsBox(1.0f, 1.0f);
+		return;
+	}
+	
+	int32 n = b2Min(count, b2_maxPolygonVertices);
+
+	// Perform welding and copy vertices into local buffer.
+	b2Vec2 ps[b2_maxPolygonVertices];
+	int32 tempCount = 0;
+	for (int32 i = 0; i < n; ++i)
+	{
+		b2Vec2 v = vertices[i];
+
+		bool unique = true;
+		for (int32 j = 0; j < tempCount; ++j)
+		{
+			if (b2DistanceSquared(v, ps[j]) < ((0.5f * b2_linearSlop) * (0.5f * b2_linearSlop)))
+			{
+				unique = false;
+				break;
+			}
+		}
+
+		if (unique)
+		{
+			ps[tempCount++] = v;
+		}
+	}
+
+	n = tempCount;
+	if (n < 3)
+	{
+		// Polygon is degenerate.
+		b2Assert(false);
+		SetAsBox(1.0f, 1.0f);
+		return;
+	}
+
+	// Create the convex hull using the Gift wrapping algorithm
+	// http://en.wikipedia.org/wiki/Gift_wrapping_algorithm
+
+	// Find the right most point on the hull
+	int32 i0 = 0;
+	float x0 = ps[0].x;
+	for (int32 i = 1; i < n; ++i)
+	{
+		float x = ps[i].x;
+		if (x > x0 || (x == x0 && ps[i].y < ps[i0].y))
+		{
+			i0 = i;
+			x0 = x;
+		}
+	}
+
+	int32 hull[b2_maxPolygonVertices];
+	int32 m = 0;
+	int32 ih = i0;
+
+	for (;;)
+	{
+		b2Assert(m < b2_maxPolygonVertices);
+		hull[m] = ih;
+
+		int32 ie = 0;
+		for (int32 j = 1; j < n; ++j)
+		{
+			if (ie == ih)
+			{
+				ie = j;
+				continue;
+			}
+
+			b2Vec2 r = ps[ie] - ps[hull[m]];
+			b2Vec2 v = ps[j] - ps[hull[m]];
+			float c = b2Cross(r, v);
+			if (c < 0.0f)
+			{
+				ie = j;
+			}
+
+			// Collinearity check
+			if (c == 0.0f && v.LengthSquared() > r.LengthSquared())
+			{
+				ie = j;
+			}
+		}
+
+		++m;
+		ih = ie;
+
+		if (ie == i0)
+		{
+			break;
+		}
+	}
+	
+	if (m < 3)
+	{
+		// Polygon is degenerate.
+		b2Assert(false);
+		SetAsBox(1.0f, 1.0f);
+		return;
+	}
+
+	m_count = m;
+
+	// Copy vertices.
+	for (int32 i = 0; i < m; ++i)
+	{
+		m_vertices[i] = ps[hull[i]];
+	}
+
+	// Compute normals. Ensure the edges have non-zero length.
+	for (int32 i = 0; i < m; ++i)
+	{
+		int32 i1 = i;
+		int32 i2 = i + 1 < m ? i + 1 : 0;
+		b2Vec2 edge = m_vertices[i2] - m_vertices[i1];
+		b2Assert(edge.LengthSquared() > b2_epsilon * b2_epsilon);
+		m_normals[i] = b2Cross(edge, 1.0f);
+		m_normals[i].Normalize();
+	}
+
+	// Compute the polygon centroid.
+	m_centroid = ComputeCentroid(m_vertices, m);
+}
+
+bool b2PolygonShape::TestPoint(const b2Transform& xf, const b2Vec2& p) const
+{
+	b2Vec2 pLocal = b2MulT(xf.q, p - xf.p);
+
+	for (int32 i = 0; i < m_count; ++i)
+	{
+		float dot = b2Dot(m_normals[i], pLocal - m_vertices[i]);
+		if (dot > 0.0f)
+		{
+			return false;
+		}
+	}
+
+	return true;
+}
+
+bool b2PolygonShape::RayCast(b2RayCastOutput* output, const b2RayCastInput& input,
+								const b2Transform& xf, int32 childIndex) const
+{
+	B2_NOT_USED(childIndex);
+
+	// Put the ray into the polygon's frame of reference.
+	b2Vec2 p1 = b2MulT(xf.q, input.p1 - xf.p);
+	b2Vec2 p2 = b2MulT(xf.q, input.p2 - xf.p);
+	b2Vec2 d = p2 - p1;
+
+	float lower = 0.0f, upper = input.maxFraction;
+
+	int32 index = -1;
+
+	for (int32 i = 0; i < m_count; ++i)
+	{
+		// p = p1 + a * d
+		// dot(normal, p - v) = 0
+		// dot(normal, p1 - v) + a * dot(normal, d) = 0
+		float numerator = b2Dot(m_normals[i], m_vertices[i] - p1);
+		float denominator = b2Dot(m_normals[i], d);
+
+		if (denominator == 0.0f)
+		{	
+			if (numerator < 0.0f)
+			{
+				return false;
+			}
+		}
+		else
+		{
+			// Note: we want this predicate without division:
+			// lower < numerator / denominator, where denominator < 0
+			// Since denominator < 0, we have to flip the inequality:
+			// lower < numerator / denominator <==> denominator * lower > numerator.
+			if (denominator < 0.0f && numerator < lower * denominator)
+			{
+				// Increase lower.
+				// The segment enters this half-space.
+				lower = numerator / denominator;
+				index = i;
+			}
+			else if (denominator > 0.0f && numerator < upper * denominator)
+			{
+				// Decrease upper.
+				// The segment exits this half-space.
+				upper = numerator / denominator;
+			}
+		}
+
+		// The use of epsilon here causes the assert on lower to trip
+		// in some cases. Apparently the use of epsilon was to make edge
+		// shapes work, but now those are handled separately.
+		//if (upper < lower - b2_epsilon)
+		if (upper < lower)
+		{
+			return false;
+		}
+	}
+
+	b2Assert(0.0f <= lower && lower <= input.maxFraction);
+
+	if (index >= 0)
+	{
+		output->fraction = lower;
+		output->normal = b2Mul(xf.q, m_normals[index]);
+		return true;
+	}
+
+	return false;
+}
+
+void b2PolygonShape::ComputeAABB(b2AABB* aabb, const b2Transform& xf, int32 childIndex) const
+{
+	B2_NOT_USED(childIndex);
+
+	b2Vec2 lower = b2Mul(xf, m_vertices[0]);
+	b2Vec2 upper = lower;
+
+	for (int32 i = 1; i < m_count; ++i)
+	{
+		b2Vec2 v = b2Mul(xf, m_vertices[i]);
+		lower = b2Min(lower, v);
+		upper = b2Max(upper, v);
+	}
+
+	b2Vec2 r(m_radius, m_radius);
+	aabb->lowerBound = lower - r;
+	aabb->upperBound = upper + r;
+}
+
+void b2PolygonShape::ComputeMass(b2MassData* massData, float density) const
+{
+	// Polygon mass, centroid, and inertia.
+	// Let rho be the polygon density in mass per unit area.
+	// Then:
+	// mass = rho * int(dA)
+	// centroid.x = (1/mass) * rho * int(x * dA)
+	// centroid.y = (1/mass) * rho * int(y * dA)
+	// I = rho * int((x*x + y*y) * dA)
+	//
+	// We can compute these integrals by summing all the integrals
+	// for each triangle of the polygon. To evaluate the integral
+	// for a single triangle, we make a change of variables to
+	// the (u,v) coordinates of the triangle:
+	// x = x0 + e1x * u + e2x * v
+	// y = y0 + e1y * u + e2y * v
+	// where 0 <= u && 0 <= v && u + v <= 1.
+	//
+	// We integrate u from [0,1-v] and then v from [0,1].
+	// We also need to use the Jacobian of the transformation:
+	// D = cross(e1, e2)
+	//
+	// Simplification: triangle centroid = (1/3) * (p1 + p2 + p3)
+	//
+	// The rest of the derivation is handled by computer algebra.
+
+	b2Assert(m_count >= 3);
+
+	b2Vec2 center(0.0f, 0.0f);
+	float area = 0.0f;
+	float I = 0.0f;
+
+	// Get a reference point for forming triangles.
+	// Use the first vertex to reduce round-off errors.
+	b2Vec2 s = m_vertices[0];
+
+	const float k_inv3 = 1.0f / 3.0f;
+
+	for (int32 i = 0; i < m_count; ++i)
+	{
+		// Triangle vertices.
+		b2Vec2 e1 = m_vertices[i] - s;
+		b2Vec2 e2 = i + 1 < m_count ? m_vertices[i+1] - s : m_vertices[0] - s;
+
+		float D = b2Cross(e1, e2);
+
+		float triangleArea = 0.5f * D;
+		area += triangleArea;
+
+		// Area weighted centroid
+		center += triangleArea * k_inv3 * (e1 + e2);
+
+		float ex1 = e1.x, ey1 = e1.y;
+		float ex2 = e2.x, ey2 = e2.y;
+
+		float intx2 = ex1*ex1 + ex2*ex1 + ex2*ex2;
+		float inty2 = ey1*ey1 + ey2*ey1 + ey2*ey2;
+
+		I += (0.25f * k_inv3 * D) * (intx2 + inty2);
+	}
+
+	// Total mass
+	massData->mass = density * area;
+
+	// Center of mass
+	b2Assert(area > b2_epsilon);
+	center *= 1.0f / area;
+	massData->center = center + s;
+
+	// Inertia tensor relative to the local origin (point s).
+	massData->I = density * I;
+	
+	// Shift to center of mass then to original body origin.
+	massData->I += massData->mass * (b2Dot(massData->center, massData->center) - b2Dot(center, center));
+}
+
+bool b2PolygonShape::Validate() const
+{
+	for (int32 i = 0; i < m_count; ++i)
+	{
+		int32 i1 = i;
+		int32 i2 = i < m_count - 1 ? i1 + 1 : 0;
+		b2Vec2 p = m_vertices[i1];
+		b2Vec2 e = m_vertices[i2] - p;
+
+		for (int32 j = 0; j < m_count; ++j)
+		{
+			if (j == i1 || j == i2)
+			{
+				continue;
+			}
+
+			b2Vec2 v = m_vertices[j] - p;
+			float c = b2Cross(e, v);
+			if (c < 0.0f)
+			{
+				return false;
+			}
+		}
+	}
+
+	return true;
+}