paulxstretch/deps/juce/modules/juce_box2d/box2d/Collision/b2TimeOfImpact.cpp
essej 25bd5d8adb git subrepo clone --branch=sono6good https://github.com/essej/JUCE.git deps/juce
subrepo:
  subdir:   "deps/juce"
  merged:   "b13f9084e"
upstream:
  origin:   "https://github.com/essej/JUCE.git"
  branch:   "sono6good"
  commit:   "b13f9084e"
git-subrepo:
  version:  "0.4.3"
  origin:   "https://github.com/ingydotnet/git-subrepo.git"
  commit:   "2f68596"
2022-04-18 17:51:22 -04:00

477 lines
12 KiB
C++

/*
* Copyright (c) 2007-2009 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.
*/
#include "b2Collision.h"
#include "b2Distance.h"
#include "b2TimeOfImpact.h"
#include "Shapes/b2CircleShape.h"
#include "Shapes/b2PolygonShape.h"
#include <cstdio>
using namespace std;
int32 b2_toiCalls, b2_toiIters, b2_toiMaxIters;
int32 b2_toiRootIters, b2_toiMaxRootIters;
struct b2SeparationFunction
{
enum Type
{
e_points,
e_faceA,
e_faceB
};
// TODO_ERIN might not need to return the separation
float32 Initialize(const b2SimplexCache* cache,
const b2DistanceProxy* proxyA, const b2Sweep& sweepA,
const b2DistanceProxy* proxyB, const b2Sweep& sweepB,
float32 t1)
{
m_proxyA = proxyA;
m_proxyB = proxyB;
int32 count = cache->count;
b2Assert(0 < count && count < 3);
m_sweepA = sweepA;
m_sweepB = sweepB;
b2Transform xfA, xfB;
m_sweepA.GetTransform(&xfA, t1);
m_sweepB.GetTransform(&xfB, t1);
if (count == 1)
{
m_type = e_points;
b2Vec2 localPointA = m_proxyA->GetVertex(cache->indexA[0]);
b2Vec2 localPointB = m_proxyB->GetVertex(cache->indexB[0]);
b2Vec2 pointA = b2Mul(xfA, localPointA);
b2Vec2 pointB = b2Mul(xfB, localPointB);
m_axis = pointB - pointA;
float32 s = m_axis.Normalize();
return s;
}
else if (cache->indexA[0] == cache->indexA[1])
{
// Two points on B and one on A.
m_type = e_faceB;
b2Vec2 localPointB1 = proxyB->GetVertex(cache->indexB[0]);
b2Vec2 localPointB2 = proxyB->GetVertex(cache->indexB[1]);
m_axis = b2Cross(localPointB2 - localPointB1, 1.0f);
m_axis.Normalize();
b2Vec2 normal = b2Mul(xfB.q, m_axis);
m_localPoint = 0.5f * (localPointB1 + localPointB2);
b2Vec2 pointB = b2Mul(xfB, m_localPoint);
b2Vec2 localPointA = proxyA->GetVertex(cache->indexA[0]);
b2Vec2 pointA = b2Mul(xfA, localPointA);
float32 s = b2Dot(pointA - pointB, normal);
if (s < 0.0f)
{
m_axis = -m_axis;
s = -s;
}
return s;
}
else
{
// Two points on A and one or two points on B.
m_type = e_faceA;
b2Vec2 localPointA1 = m_proxyA->GetVertex(cache->indexA[0]);
b2Vec2 localPointA2 = m_proxyA->GetVertex(cache->indexA[1]);
m_axis = b2Cross(localPointA2 - localPointA1, 1.0f);
m_axis.Normalize();
b2Vec2 normal = b2Mul(xfA.q, m_axis);
m_localPoint = 0.5f * (localPointA1 + localPointA2);
b2Vec2 pointA = b2Mul(xfA, m_localPoint);
b2Vec2 localPointB = m_proxyB->GetVertex(cache->indexB[0]);
b2Vec2 pointB = b2Mul(xfB, localPointB);
float32 s = b2Dot(pointB - pointA, normal);
if (s < 0.0f)
{
m_axis = -m_axis;
s = -s;
}
return s;
}
}
float32 FindMinSeparation(int32* indexA, int32* indexB, float32 t) const
{
b2Transform xfA, xfB;
m_sweepA.GetTransform(&xfA, t);
m_sweepB.GetTransform(&xfB, t);
switch (m_type)
{
case e_points:
{
b2Vec2 axisA = b2MulT(xfA.q, m_axis);
b2Vec2 axisB = b2MulT(xfB.q, -m_axis);
*indexA = m_proxyA->GetSupport(axisA);
*indexB = m_proxyB->GetSupport(axisB);
b2Vec2 localPointA = m_proxyA->GetVertex(*indexA);
b2Vec2 localPointB = m_proxyB->GetVertex(*indexB);
b2Vec2 pointA = b2Mul(xfA, localPointA);
b2Vec2 pointB = b2Mul(xfB, localPointB);
float32 separation = b2Dot(pointB - pointA, m_axis);
return separation;
}
case e_faceA:
{
b2Vec2 normal = b2Mul(xfA.q, m_axis);
b2Vec2 pointA = b2Mul(xfA, m_localPoint);
b2Vec2 axisB = b2MulT(xfB.q, -normal);
*indexA = -1;
*indexB = m_proxyB->GetSupport(axisB);
b2Vec2 localPointB = m_proxyB->GetVertex(*indexB);
b2Vec2 pointB = b2Mul(xfB, localPointB);
float32 separation = b2Dot(pointB - pointA, normal);
return separation;
}
case e_faceB:
{
b2Vec2 normal = b2Mul(xfB.q, m_axis);
b2Vec2 pointB = b2Mul(xfB, m_localPoint);
b2Vec2 axisA = b2MulT(xfA.q, -normal);
*indexB = -1;
*indexA = m_proxyA->GetSupport(axisA);
b2Vec2 localPointA = m_proxyA->GetVertex(*indexA);
b2Vec2 pointA = b2Mul(xfA, localPointA);
float32 separation = b2Dot(pointA - pointB, normal);
return separation;
}
default:
b2Assert(false);
*indexA = -1;
*indexB = -1;
return 0.0f;
}
}
float32 Evaluate(int32 indexA, int32 indexB, float32 t) const
{
b2Transform xfA, xfB;
m_sweepA.GetTransform(&xfA, t);
m_sweepB.GetTransform(&xfB, t);
switch (m_type)
{
case e_points:
{
b2Vec2 localPointA = m_proxyA->GetVertex(indexA);
b2Vec2 localPointB = m_proxyB->GetVertex(indexB);
b2Vec2 pointA = b2Mul(xfA, localPointA);
b2Vec2 pointB = b2Mul(xfB, localPointB);
float32 separation = b2Dot(pointB - pointA, m_axis);
return separation;
}
case e_faceA:
{
b2Vec2 normal = b2Mul(xfA.q, m_axis);
b2Vec2 pointA = b2Mul(xfA, m_localPoint);
b2Vec2 localPointB = m_proxyB->GetVertex(indexB);
b2Vec2 pointB = b2Mul(xfB, localPointB);
float32 separation = b2Dot(pointB - pointA, normal);
return separation;
}
case e_faceB:
{
b2Vec2 normal = b2Mul(xfB.q, m_axis);
b2Vec2 pointB = b2Mul(xfB, m_localPoint);
b2Vec2 localPointA = m_proxyA->GetVertex(indexA);
b2Vec2 pointA = b2Mul(xfA, localPointA);
float32 separation = b2Dot(pointA - pointB, normal);
return separation;
}
default:
b2Assert(false);
return 0.0f;
}
}
const b2DistanceProxy* m_proxyA;
const b2DistanceProxy* m_proxyB;
b2Sweep m_sweepA, m_sweepB;
Type m_type;
b2Vec2 m_localPoint;
b2Vec2 m_axis;
};
// CCD via the local separating axis method. This seeks progression
// by computing the largest time at which separation is maintained.
void b2TimeOfImpact(b2TOIOutput* output, const b2TOIInput* input)
{
++b2_toiCalls;
output->state = b2TOIOutput::e_unknown;
output->t = input->tMax;
const b2DistanceProxy* proxyA = &input->proxyA;
const b2DistanceProxy* proxyB = &input->proxyB;
b2Sweep sweepA = input->sweepA;
b2Sweep sweepB = input->sweepB;
// Large rotations can make the root finder fail, so we normalize the
// sweep angles.
sweepA.Normalize();
sweepB.Normalize();
float32 tMax = input->tMax;
float32 totalRadius = proxyA->m_radius + proxyB->m_radius;
float32 target = b2Max(b2_linearSlop, totalRadius - 3.0f * b2_linearSlop);
float32 tolerance = 0.25f * b2_linearSlop;
b2Assert(target > tolerance);
float32 t1 = 0.0f;
const int32 k_maxIterations = 20; // TODO_ERIN b2Settings
int32 iter = 0;
// Prepare input for distance query.
b2SimplexCache cache;
cache.count = 0;
b2DistanceInput distanceInput;
distanceInput.proxyA = input->proxyA;
distanceInput.proxyB = input->proxyB;
distanceInput.useRadii = false;
// The outer loop progressively attempts to compute new separating axes.
// This loop terminates when an axis is repeated (no progress is made).
for(;;)
{
b2Transform xfA, xfB;
sweepA.GetTransform(&xfA, t1);
sweepB.GetTransform(&xfB, t1);
// Get the distance between shapes. We can also use the results
// to get a separating axis.
distanceInput.transformA = xfA;
distanceInput.transformB = xfB;
b2DistanceOutput distanceOutput;
b2Distance(&distanceOutput, &cache, &distanceInput);
// If the shapes are overlapped, we give up on continuous collision.
if (distanceOutput.distance <= 0.0f)
{
// Failure!
output->state = b2TOIOutput::e_overlapped;
output->t = 0.0f;
break;
}
if (distanceOutput.distance < target + tolerance)
{
// Victory!
output->state = b2TOIOutput::e_touching;
output->t = t1;
break;
}
// Initialize the separating axis.
b2SeparationFunction fcn;
fcn.Initialize(&cache, proxyA, sweepA, proxyB, sweepB, t1);
#if 0
// Dump the curve seen by the root finder
{
const int32 N = 100;
float32 dx = 1.0f / N;
float32 xs[N+1];
float32 fs[N+1];
float32 x = 0.0f;
for (int32 i = 0; i <= N; ++i)
{
sweepA.GetTransform(&xfA, x);
sweepB.GetTransform(&xfB, x);
float32 f = fcn.Evaluate(xfA, xfB) - target;
printf("%g %g\n", x, f);
xs[i] = x;
fs[i] = f;
x += dx;
}
}
#endif
// Compute the TOI on the separating axis. We do this by successively
// resolving the deepest point. This loop is bounded by the number of vertices.
bool done = false;
float32 t2 = tMax;
int32 pushBackIter = 0;
for (;;)
{
// Find the deepest point at t2. Store the witness point indices.
int32 indexA, indexB;
float32 s2 = fcn.FindMinSeparation(&indexA, &indexB, t2);
// Is the final configuration separated?
if (s2 > target + tolerance)
{
// Victory!
output->state = b2TOIOutput::e_separated;
output->t = tMax;
done = true;
break;
}
// Has the separation reached tolerance?
if (s2 > target - tolerance)
{
// Advance the sweeps
t1 = t2;
break;
}
// Compute the initial separation of the witness points.
float32 s1 = fcn.Evaluate(indexA, indexB, t1);
// Check for initial overlap. This might happen if the root finder
// runs out of iterations.
if (s1 < target - tolerance)
{
output->state = b2TOIOutput::e_failed;
output->t = t1;
done = true;
break;
}
// Check for touching
if (s1 <= target + tolerance)
{
// Victory! t1 should hold the TOI (could be 0.0).
output->state = b2TOIOutput::e_touching;
output->t = t1;
done = true;
break;
}
// Compute 1D root of: f(x) - target = 0
int32 rootIterCount = 0;
float32 a1 = t1, a2 = t2;
for (;;)
{
// Use a mix of the secant rule and bisection.
float32 t;
if (rootIterCount & 1)
{
// Secant rule to improve convergence.
t = a1 + (target - s1) * (a2 - a1) / (s2 - s1);
}
else
{
// Bisection to guarantee progress.
t = 0.5f * (a1 + a2);
}
float32 s = fcn.Evaluate(indexA, indexB, t);
if (b2Abs(s - target) < tolerance)
{
// t2 holds a tentative value for t1
t2 = t;
break;
}
// Ensure we continue to bracket the root.
if (s > target)
{
a1 = t;
s1 = s;
}
else
{
a2 = t;
s2 = s;
}
++rootIterCount;
++b2_toiRootIters;
if (rootIterCount == 50)
{
break;
}
}
b2_toiMaxRootIters = b2Max(b2_toiMaxRootIters, rootIterCount);
++pushBackIter;
if (pushBackIter == b2_maxPolygonVertices)
{
break;
}
}
++iter;
++b2_toiIters;
if (done)
{
break;
}
if (iter == k_maxIterations)
{
// Root finder got stuck. Semi-victory.
output->state = b2TOIOutput::e_failed;
output->t = t1;
break;
}
}
b2_toiMaxIters = b2Max(b2_toiMaxIters, iter);
}