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authorchai <chaifix@163.com>2021-12-13 00:07:19 +0800
committerchai <chaifix@163.com>2021-12-13 00:07:19 +0800
commit60cbbdec07ab7a5636eac5b3c024ae44e937f4d4 (patch)
treeb2c7b0a868f18159dbc43d8954e1bd7668549a88 /Client/ThirdParty/Box2D/src/collision/b2_collision.cpp
+init
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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_collision.h"
+#include "box2d/b2_distance.h"
+
+void b2WorldManifold::Initialize(const b2Manifold* manifold,
+ const b2Transform& xfA, float radiusA,
+ const b2Transform& xfB, float 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);
+ separations[0] = b2Dot(cB - cA, normal);
+ }
+ 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);
+ separations[i] = b2Dot(cB - cA, normal);
+ }
+ }
+ 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);
+ separations[i] = b2Dot(cA - cB, normal);
+ }
+
+ // 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
+{
+ float tmin = -b2_maxFloat;
+ float 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
+ {
+ float inv_d = 1.0f / d(i);
+ float t1 = (lowerBound(i) - p(i)) * inv_d;
+ float t2 = (upperBound(i) - p(i)) * inv_d;
+
+ // Sign of the normal vector.
+ float 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, float offset, int32 vertexIndexA)
+{
+ // Start with no output points
+ int32 count = 0;
+
+ // Calculate the distance of end points to the line
+ float distance0 = b2Dot(normal, vIn[0].v) - offset;
+ float distance1 = b2Dot(normal, vIn[1].v) - offset;
+
+ // If the points are behind the plane
+ if (distance0 <= 0.0f) vOut[count++] = vIn[0];
+ if (distance1 <= 0.0f) vOut[count++] = vIn[1];
+
+ // If the points are on different sides of the plane
+ if (distance0 * distance1 < 0.0f)
+ {
+ // Find intersection point of edge and plane
+ float interp = distance0 / (distance0 - distance1);
+ vOut[count].v = vIn[0].v + interp * (vIn[1].v - vIn[0].v);
+
+ // VertexA is hitting edgeB.
+ vOut[count].id.cf.indexA = static_cast<uint8>(vertexIndexA);
+ vOut[count].id.cf.indexB = vIn[0].id.cf.indexB;
+ vOut[count].id.cf.typeA = b2ContactFeature::e_vertex;
+ vOut[count].id.cf.typeB = b2ContactFeature::e_face;
+ ++count;
+
+ b2Assert(count == 2);
+ }
+
+ return count;
+}
+
+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;
+}