JoltPhysics/Samples/Tests/ConvexCollision/EPATest.cpp

// SPDX-FileCopyrightText: 2021 Jorrit Rouwe
// SPDX-License-Identifier: MIT

#include <TestFramework.h>

#include <Tests/ConvexCollision/EPATest.h>
#include <Jolt/Geometry/Sphere.h>
#include <Jolt/Geometry/AABox.h>
#include <Jolt/Geometry/ConvexSupport.h>
#include <Jolt/Geometry/EPAPenetrationDepth.h>
#include <Renderer/DebugRendererImp.h>

JPH_IMPLEMENT_RTTI_VIRTUAL(EPATest) 
{ 
	JPH_ADD_BASE_CLASS(EPATest, Test) 
}

void EPATest::PrePhysicsUpdate(const PreUpdateParams &inParams)
{
	AABox box(Vec3(1, 1, -2), Vec3(2, 2, 2));
	Sphere sphere(Vec3(4, 4, 0), sqrt(8.0f) + 0.01f);
	Mat44 matrix = Mat44::sRotationTranslation(Quat::sRotation(Vec3(1, 1, 1).Normalized(), 0.25f * JPH_PI), Vec3(1, 2, 3));
	bool intersecting = CollideBoxSphere(matrix, box, sphere);
	JPH_ASSERT(intersecting);
	(void)intersecting; // For when asserts are off
}

bool EPATest::CollideBoxSphere(Mat44Arg inMatrix, const AABox &inBox, const Sphere &inSphere) const
{
	// Draw the box and shere
	mDebugRenderer->DrawBox(inMatrix, inBox, Color::sGrey);
	mDebugRenderer->DrawSphere(inMatrix * inSphere.GetCenter(), inSphere.GetRadius(), Color::sGrey); 

	// Transform the box and sphere according to inMatrix
	TransformedConvexObject<AABox> transformed_box(inMatrix, inBox);
	TransformedConvexObject<Sphere> transformed_sphere(inMatrix, inSphere);

	// Run the EPA algorithm
	EPAPenetrationDepth epa;
	Vec3 v1 = Vec3::sAxisX(), pa1, pb1;
	bool intersect1 = epa.GetPenetrationDepth(transformed_box, transformed_box, 0.0f, transformed_sphere, transformed_sphere, 0.0f, 1.0e-2f, FLT_EPSILON, v1, pa1, pb1);

	// Draw iterative solution
	if (intersect1)
	{
		mDebugRenderer->DrawMarker(pa1, Color::sRed, 1.0f);
		mDebugRenderer->DrawMarker(pb1, Color::sGreen, 1.0f);
		mDebugRenderer->DrawArrow(pb1 + Vec3(0, 1, 0), pb1 + Vec3(0, 1, 0) + v1, Color::sYellow, 0.1f);
	}

	// Calculate analytical solution
	Vec3 pa2 = inBox.GetClosestPoint(inSphere.GetCenter());
	Vec3 v2 = inSphere.GetCenter() - pa2;
	bool intersect2 = v2.LengthSq() <= Square(inSphere.GetRadius());

	JPH_ASSERT(intersect1 == intersect2);
	if (intersect1 && intersect2)
	{
		Vec3 pb2 = inSphere.GetCenter() - inSphere.GetRadius() * v2.NormalizedOr(Vec3::sZero());

		// Transform analytical solution
		v2 = inMatrix.Multiply3x3(v2);
		pa2 = inMatrix * pa2;
		pb2 = inMatrix * pb2;

		// Draw analytical solution
		mDebugRenderer->DrawMarker(pa2, Color::sOrange, 1.0f);
		mDebugRenderer->DrawMarker(pb2, Color::sYellow, 1.0f);

		// Check angle between v1 and v2
		float dot = v1.Dot(v2);
		float len = v1.Length() * v2.Length();
		float angle = RadiansToDegrees(ACos(dot / len));
		JPH_ASSERT(angle < 0.1f);
		Trace("Angle = %.9g", (double)angle);

		// Check delta between contact on A
		Vec3 dpa = pa2 - pa1;
		JPH_ASSERT(dpa.IsNearZero(Square(8.0e-4f)));
		Trace("Delta A = %.9g", (double)dpa.Length());

		// Check delta between contact on B
		Vec3 dpb = pb2 - pb1;
		JPH_ASSERT(dpb.IsNearZero(Square(8.0e-4f)));
		Trace("Delta B = %.9g", (double)dpb.Length());
	}

	return intersect1;
}