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src/bounce/dynamics/shapes/mesh_shape.cpp

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+/*
+* Copyright (c) 2016-2016 Irlan Robson http://www.irlan.net
+*
+* 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.
+*/
+
+#include <bounce\dynamics\shapes\mesh_shape.h>
+#include <bounce\collision\shapes\mesh.h>
+
+b3MeshShape::b3MeshShape() 
+{
+	m_type = e_meshShape;
+	m_radius = B3_HULL_RADIUS;
+	m_mesh = nullptr;
+}
+
+b3MeshShape::~b3MeshShape() 
+{
+}
+
+void b3MeshShape::Swap(const b3MeshShape& other) 
+{
+	m_radius = other.m_radius;
+	m_mesh = other.m_mesh;
+}
+
+void b3MeshShape::ComputeMass(b3MassData* massData, float32 density) const 
+{
+	B3_NOT_USED(density);
+	u32 n = m_mesh->vertexCount;
+	b3Vec3 c(0.0f, 0.0f, 0.0f);
+	for (u32 i = 0; i < n; ++i)
+	{
+		c += m_mesh->vertices[i];
+	}
+	if (n > 0)
+	{
+		c = 1.0f / float32(n) * c;
+	}	
+	massData->center = c;
+	massData->mass = 0.0f;
+	massData->I.SetZero();
+}
+
+void b3MeshShape::ComputeAABB(b3AABB3* output, const b3Transform& xf) const 
+{
+	output->Compute(m_mesh->vertices, m_mesh->vertexCount, xf);
+	output->Extend(m_radius);
+}
+
+void b3MeshShape::ComputeAABB(b3AABB3* output, const b3Transform& xf, u32 index) const
+{
+	*output = m_mesh->GetTriangleAABB(index);
+}
+
+bool b3MeshShape::TestPoint(const b3Vec3& point, const b3Transform& xf) const
+{
+	B3_NOT_USED(point);
+	B3_NOT_USED(xf);
+	return false;
+}
+
+bool b3MeshShape::RayCast(b3RayCastOutput* output, const b3RayCastInput& input, const b3Transform& xf, u32 index) const
+{
+	B3_ASSERT(index < m_mesh->triangleCount);
+	b3Triangle* triangle = m_mesh->triangles + index;
+
+	b3Vec3 p1 = input.p1;
+	b3Vec3 p2 = input.p2;
+	b3Vec3 d = p2 - p1;
+
+	b3Vec3 v1 = m_mesh->vertices[triangle->v1];
+	b3Vec3 v2 = m_mesh->vertices[triangle->v2];
+	b3Vec3 v3 = m_mesh->vertices[triangle->v3];
+
+	b3Vec3 n = b3Cross(v2 - v1, v3 - v1);
+	n.Normalize();
+	float32 offset = b3Dot(n, v1);
+
+	float32 numerator = b3Dot(n, v1 - p1);
+	float32 denominator = b3Dot(n, d);
+
+	if (denominator == 0.0f)
+	{
+		return false;
+	}
+
+	float32 t = numerator / denominator;
+	if (t < 0.0f || input.maxFraction < t)
+	{
+		return false;
+	}
+
+	b3Vec3 q = p1 + t * d;
+
+	float32 w[4];
+	b3Barycentric(w, v1, v2, v3, q);
+
+	if (w[0] > 0.0f && w[1] > 0.0f && w[2] > 0.0f)
+	{
+		output->fraction = t;
+		if (numerator > 0.0f)
+		{
+			output->normal = -n;
+		}
+		else
+		{
+			output->normal = n;
+		}
+		return true;
+	}
+
+	return false;
+}
+
+struct b3MeshRayCastCallback
+{
+	float32 Report(const b3RayCastInput& input, u32 proxyId)
+	{
+		u32 index = mesh->m_mesh->tree.GetUserData(proxyId);
+		b3RayCastOutput indexOutput;
+		if (mesh->RayCast(&indexOutput, input, xf, index))
+		{
+			hit = true;
+			if (indexOutput.fraction < output.fraction)
+			{
+				output = indexOutput;
+			}
+		}
+		return 1.0f;
+	}
+
+	b3Transform xf;
+	const b3MeshShape* mesh;
+	bool hit;
+	b3RayCastOutput output;
+};
+
+bool b3MeshShape::RayCast(b3RayCastOutput* output, const b3RayCastInput& input, const b3Transform& xf) const 
+{
+	// Put the ray into the mesh's frame of reference.
+	b3RayCastInput subInput;
+	subInput.p1 = b3MulT(xf.rotation, input.p1 - xf.position);
+	subInput.p2 = b3MulT(xf.rotation, input.p2 - xf.position);
+	subInput.maxFraction = input.maxFraction;
+
+	b3MeshRayCastCallback callback;
+	callback.mesh = this;
+	callback.hit = false;
+	callback.output.fraction = B3_MAX_FLOAT;
+
+	m_mesh->tree.QueryRay(&callback, subInput);
+
+	output->fraction = callback.output.fraction;
+	output->normal = b3Mul(xf.rotation, callback.output.normal);
+
+	return callback.hit;
+}