paulxstretch/deps/juce/modules/juce_box2d/box2d/Collision/b2Collision.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

250 lines
6.3 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"
void b2WorldManifold::Initialize(const b2Manifold* manifold,
const b2Transform& xfA, float32 radiusA,
const b2Transform& xfB, float32 radiusB)
{
if (manifold->pointCount == 0)
{
return;
}
switch (manifold->type)
{
case b2Manifold::e_circles:
{
normal.Set(1.0f, 0.0f);
b2Vec2 pointA = b2Mul(xfA, manifold->localPoint);
b2Vec2 pointB = b2Mul(xfB, manifold->points[0].localPoint);
if (b2DistanceSquared(pointA, pointB) > b2_epsilon * b2_epsilon)
{
normal = pointB - pointA;
normal.Normalize();
}
b2Vec2 cA = pointA + radiusA * normal;
b2Vec2 cB = pointB - radiusB * normal;
points[0] = 0.5f * (cA + cB);
}
break;
case b2Manifold::e_faceA:
{
normal = b2Mul(xfA.q, manifold->localNormal);
b2Vec2 planePoint = b2Mul(xfA, manifold->localPoint);
for (int32 i = 0; i < manifold->pointCount; ++i)
{
b2Vec2 clipPoint = b2Mul(xfB, manifold->points[i].localPoint);
b2Vec2 cA = clipPoint + (radiusA - b2Dot(clipPoint - planePoint, normal)) * normal;
b2Vec2 cB = clipPoint - radiusB * normal;
points[i] = 0.5f * (cA + cB);
}
}
break;
case b2Manifold::e_faceB:
{
normal = b2Mul(xfB.q, manifold->localNormal);
b2Vec2 planePoint = b2Mul(xfB, manifold->localPoint);
for (int32 i = 0; i < manifold->pointCount; ++i)
{
b2Vec2 clipPoint = b2Mul(xfA, manifold->points[i].localPoint);
b2Vec2 cB = clipPoint + (radiusB - b2Dot(clipPoint - planePoint, normal)) * normal;
b2Vec2 cA = clipPoint - radiusA * normal;
points[i] = 0.5f * (cA + cB);
}
// Ensure normal points from A to B.
normal = -normal;
}
break;
}
}
void b2GetPointStates(b2PointState state1[b2_maxManifoldPoints], b2PointState state2[b2_maxManifoldPoints],
const b2Manifold* manifold1, const b2Manifold* manifold2)
{
for (int32 i = 0; i < b2_maxManifoldPoints; ++i)
{
state1[i] = b2_nullState;
state2[i] = b2_nullState;
}
// Detect persists and removes.
for (int32 i = 0; i < manifold1->pointCount; ++i)
{
b2ContactID id = manifold1->points[i].id;
state1[i] = b2_removeState;
for (int32 j = 0; j < manifold2->pointCount; ++j)
{
if (manifold2->points[j].id.key == id.key)
{
state1[i] = b2_persistState;
break;
}
}
}
// Detect persists and adds.
for (int32 i = 0; i < manifold2->pointCount; ++i)
{
b2ContactID id = manifold2->points[i].id;
state2[i] = b2_addState;
for (int32 j = 0; j < manifold1->pointCount; ++j)
{
if (manifold1->points[j].id.key == id.key)
{
state2[i] = b2_persistState;
break;
}
}
}
}
// From Real-time Collision Detection, p179.
bool b2AABB::RayCast(b2RayCastOutput* output, const b2RayCastInput& input) const
{
float32 tmin = -b2_maxFloat;
float32 tmax = b2_maxFloat;
b2Vec2 p = input.p1;
b2Vec2 d = input.p2 - input.p1;
b2Vec2 absD = b2Abs(d);
b2Vec2 normal;
for (int32 i = 0; i < 2; ++i)
{
if (absD(i) < b2_epsilon)
{
// Parallel.
if (p(i) < lowerBound(i) || upperBound(i) < p(i))
{
return false;
}
}
else
{
float32 inv_d = 1.0f / d(i);
float32 t1 = (lowerBound(i) - p(i)) * inv_d;
float32 t2 = (upperBound(i) - p(i)) * inv_d;
// Sign of the normal vector.
float32 s = -1.0f;
if (t1 > t2)
{
b2Swap(t1, t2);
s = 1.0f;
}
// Push the min up
if (t1 > tmin)
{
normal.SetZero();
normal(i) = s;
tmin = t1;
}
// Pull the max down
tmax = b2Min(tmax, t2);
if (tmin > tmax)
{
return false;
}
}
}
// Does the ray start inside the box?
// Does the ray intersect beyond the max fraction?
if (tmin < 0.0f || input.maxFraction < tmin)
{
return false;
}
// Intersection.
output->fraction = tmin;
output->normal = normal;
return true;
}
// Sutherland-Hodgman clipping.
int32 b2ClipSegmentToLine(b2ClipVertex vOut[2], const b2ClipVertex vIn[2],
const b2Vec2& normal, float32 offset, int32 vertexIndexA)
{
// Start with no output points
int32 numOut = 0;
// Calculate the distance of end points to the line
float32 distance0 = b2Dot(normal, vIn[0].v) - offset;
float32 distance1 = b2Dot(normal, vIn[1].v) - offset;
// If the points are behind the plane
if (distance0 <= 0.0f) vOut[numOut++] = vIn[0];
if (distance1 <= 0.0f) vOut[numOut++] = vIn[1];
// If the points are on different sides of the plane
if (distance0 * distance1 < 0.0f)
{
// Find intersection point of edge and plane
float32 interp = distance0 / (distance0 - distance1);
vOut[numOut].v = vIn[0].v + interp * (vIn[1].v - vIn[0].v);
// VertexA is hitting edgeB.
vOut[numOut].id.cf.indexA = (uint8) vertexIndexA;
vOut[numOut].id.cf.indexB = vIn[0].id.cf.indexB;
vOut[numOut].id.cf.typeA = b2ContactFeature::e_vertex;
vOut[numOut].id.cf.typeB = b2ContactFeature::e_face;
++numOut;
}
return numOut;
}
bool b2TestOverlap( const b2Shape* shapeA, int32 indexA,
const b2Shape* shapeB, int32 indexB,
const b2Transform& xfA, const b2Transform& xfB)
{
b2DistanceInput input;
input.proxyA.Set(shapeA, indexA);
input.proxyB.Set(shapeB, indexB);
input.transformA = xfA;
input.transformB = xfB;
input.useRadii = true;
b2SimplexCache cache;
cache.count = 0;
b2DistanceOutput output;
b2Distance(&output, &cache, &input);
return output.distance < 10.0f * b2_epsilon;
}