GuInternal.h

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// Copyright (c) 2004-2008 AGEIA Technologies, Inc. All rights reserved.
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#ifndef GU_INTERNAL_H
#define GU_INTERNAL_H
 
#include "geometry/PxCapsuleGeometry.h"
#include "geometry/PxBoxGeometry.h"
#include "GuCapsule.h"
#include "foundation/PxTransform.h"
#include "foundation/PxMathUtils.h"
#include "foundation/PxUtilities.h"
#include "foundation/PxMat33.h"
 
#define GU_EPSILON_SAME_DISTANCE 1e-3f
 
namespace physx
{
namespace Gu
{
    class Box;
 
    // PT: TODO: now that the Gu files are not exposed to users anymore, we should move back capsule-related functions
    // to GuCapsule.h, etc
 
    PX_PHYSX_COMMON_API const PxU8* getBoxEdges();
 
    PX_PHYSX_COMMON_API void        computeBoxPoints(const PxBounds3& bounds, PxVec3* PX_RESTRICT pts);
 
                        void        computeBoxAroundCapsule(const Capsule& capsule, Box& box);
 
                        PxPlane     getPlane(const PxTransform& pose);
 
    PX_FORCE_INLINE     PxVec3      getCapsuleHalfHeightVector(const PxTransform& transform, const PxCapsuleGeometry& capsuleGeom)
                                    {
                                        return transform.q.getBasisVector0() * capsuleGeom.halfHeight;
                                    }
 
    PX_FORCE_INLINE     void        getCapsuleSegment(const PxTransform& transform, const PxCapsuleGeometry& capsuleGeom, Gu::Segment& segment)
                                    {
                                        const PxVec3 tmp = getCapsuleHalfHeightVector(transform, capsuleGeom);
                                        segment.p0 = transform.p + tmp;
                                        segment.p1 = transform.p - tmp;
                                    }
 
    PX_FORCE_INLINE     void        getCapsule(Gu::Capsule& capsule, const PxCapsuleGeometry& capsuleGeom, const PxTransform& pose)
                                    {
                                        getCapsuleSegment(pose, capsuleGeom, capsule);
                                        capsule.radius = capsuleGeom.radius;
                                    }
 
                        void        computeSweptBox(Gu::Box& box, const PxVec3& extents, const PxVec3& center, const PxMat33& rot, const PxVec3& unitDir, const PxReal distance);
 
    PX_FORCE_INLINE     PxReal      computeAlignmentValue(const PxVec3& triNormal, const PxVec3& unitDir)
    {
        PX_ASSERT(triNormal.isNormalized());
        // PT: initial dot product gives the angle between the two, with "best" triangles getting a +1 or -1 score
        // depending on their winding. We take the absolute value to ignore the impact of winding. We negate the result
        // to make the function compatible with the initial code, which assumed single-sided triangles and expected -1
        // for best triangles.
        return -PxAbs(triNormal.dot(unitDir));
    }
 
    PX_FORCE_INLINE     bool        keepTriangle(   float triImpactDistance, float triAlignmentValue,
                                                    float bestImpactDistance, float bestAlignmentValue, float maxDistance)
    {
        // Reject triangle if further than the maxDistance
        if(triImpactDistance > maxDistance)
            return false;
 
        // If initial overlap happens, keep the triangle
        if(triImpactDistance == 0.0f)
            return true;
 
        // tris have "similar" impact distances if the difference is smaller than 2*distEpsilon
        float distEpsilon = GU_EPSILON_SAME_DISTANCE; // pick a farther hit within distEpsilon that is more opposing than the previous closest hit
 
        // PT: make it a relative epsilon to make sure it still works with large distances
        distEpsilon *= PxMax(1.0f, PxMax(triImpactDistance, bestImpactDistance));
 
        // If new distance is more than epsilon closer than old distance
        if(triImpactDistance < bestImpactDistance - distEpsilon)
            return true;
 
        // If new distance is no more than epsilon farther than oldDistance and "face is more opposing than previous"
        if(triImpactDistance < bestImpactDistance+distEpsilon && triAlignmentValue < bestAlignmentValue)
            return true;
 
        // If alignment value is the same, but the new triangle is closer than the best distance
        if(triAlignmentValue == bestAlignmentValue && triImpactDistance < bestImpactDistance)
            return true;
 
        return false;
    }
 
    PX_FORCE_INLINE     bool        keepTriangleBasic(float triImpactDistance, float bestImpactDistance, float maxDistance)
    {
        // Reject triangle if further than the maxDistance
        if(triImpactDistance > maxDistance)
            return false;
 
        // If initial overlap happens, keep the triangle
        if(triImpactDistance == 0.0f)
            return true;
 
        // If new distance is more than epsilon closer than old distance
        if(triImpactDistance < bestImpactDistance)
            return true;
 
        return false;
    }
 
    PX_FORCE_INLINE PxVec3 cross100(const PxVec3& b)
    {
        return PxVec3(0.0f, -b.z, b.y);
    }
    PX_FORCE_INLINE PxVec3 cross010(const PxVec3& b)
    {
        return PxVec3(b.z, 0.0f, -b.x);
    }
    PX_FORCE_INLINE PxVec3 cross001(const PxVec3& b)
    {
        return PxVec3(-b.y, b.x, 0.0f);
    }
 
    PX_FORCE_INLINE PxVec3 computeBarycentricPoint(const PxVec3& p0, const PxVec3& p1, const PxVec3& p2, PxReal u, PxReal v)
    {
        // This seems to confuse the compiler...
        // return (1.0f - u - v)*p0 + u*p1 + v*p2;
        const PxF32 w = 1.0f - u - v;
        return PxVec3(w * p0.x + u * p1.x + v * p2.x, w * p0.y + u * p1.y + v * p2.y, w * p0.z + u * p1.z + v * p2.z);
    }
 
    PX_FORCE_INLINE PxReal computeTetrahedronVolume(const PxVec3& x0, const PxVec3& x1, const PxVec3& x2, const PxVec3& x3, PxMat33& edgeMatrix)
    {
        const PxVec3 u1 = x1 - x0;
        const PxVec3 u2 = x2 - x0;
        const PxVec3 u3 = x3 - x0;
 
        edgeMatrix = PxMat33(u1, u2, u3);
 
        const PxReal det = edgeMatrix.getDeterminant();
 
        const PxReal volume = det / 6.0f;
        return volume;
    }
 
    PX_FORCE_INLINE PxReal computeTetrahedronVolume(const PxVec3& x0, const PxVec3& x1, const PxVec3& x2, const PxVec3& x3)
    {
        PxMat33 edgeMatrix;
        return computeTetrahedronVolume(x0, x1, x2, x3, edgeMatrix);
    }
    
    // IndexType should be PxU16 or PxU32.
    template<typename IndexType>
    PX_FORCE_INLINE PxReal computeTriangleMeshVolume(const PxVec3* vertices, const IndexType* indices,
                                                     const PxU32 numTriangles)
    {
        // See https://twitter.com/keenanisalive/status/1437178786286653445?lang=en
        float volume = 0.0f;
 
        for(PxU32 i = 0; i < numTriangles; ++i)
        {
            PxVec3 v0 = vertices[indices[3*i]];
            PxVec3 v1 = vertices[indices[3 * i + 1]];
            PxVec3 v2 = vertices[indices[3 * i + 2]];
 
            PxVec3 v0v1 = v0.cross(v1);
 
            volume += v0v1.dot(v2);
        }
        return volume / 6.0f;
    }
 
    // IndexType should be PxU16 or PxU32.
    // W in PxVec4 of vertices are ignored.
    template <typename IndexType>
    PX_FORCE_INLINE PxReal computeTriangleMeshVolume(const PxVec4* vertices, const IndexType* indices,
                                                     const PxU32 numTriangles)
    {
        // See https://twitter.com/keenanisalive/status/1437178786286653445?lang=en
        float volume = 0.0f;
 
        for(PxU32 i = 0; i < numTriangles; ++i)
        {
            PxVec3 v0 = vertices[indices[3 * i]].getXYZ();
            PxVec3 v1 = vertices[indices[3 * i + 1]].getXYZ();
            PxVec3 v2 = vertices[indices[3 * i + 2]].getXYZ();
 
            PxVec3 v0v1 = v0.cross(v1);
 
            volume += v0v1.dot(v2);
        }
        return volume / 6.0f;
    }
 
    PX_FORCE_INLINE void makeFatEdge(PxVec3& p0, PxVec3& p1, PxReal fatCoeff)
    {
        PxVec3 delta = p1 - p0;
 
        const PxReal m = delta.magnitude();
        if (m > 0.0f)
        {
            delta *= fatCoeff / m;
            p0 -= delta;
            p1 += delta;
        }
    }
 
#if 0
    PX_FORCE_INLINE void makeFatEdge(aos::Vec3V& p0, aos::Vec3V& p1, const aos::FloatVArg fatCoeff)
    {
        const aos::Vec3V delta = aos::V3Sub(p1, p0);
        const aos::FloatV m = aos::V3Length(delta);
        const aos::BoolV con = aos::FIsGrtr(m, aos::FZero());
        const aos::Vec3V fatDelta = aos::V3Scale(aos::V3ScaleInv(delta, m), fatCoeff);
        p0 = aos::V3Sel(con, aos::V3Sub(p0, fatDelta), p0);
        p1 = aos::V3Sel(con, aos::V3Add(p1, fatDelta), p1);
    }
#endif
 
    PX_FORCE_INLINE PxU32 closestAxis(const PxVec3& v, PxU32& j, PxU32& k)
    {
        // find largest 2D plane projection
        const PxF32 absPx = PxAbs(v.x);
        const PxF32 absNy = PxAbs(v.y);
        const PxF32 absNz = PxAbs(v.z);
 
        PxU32 m = 0; // x biggest axis
        j = 1;
        k = 2;
        if (absNy > absPx && absNy > absNz)
        {
            // y biggest
            j = 2;
            k = 0;
            m = 1;
        }
        else if (absNz > absPx)
        {
            // z biggest
            j = 0;
            k = 1;
            m = 2;
        }
        return m;
    }
 
    PX_FORCE_INLINE bool isAlmostZero(const PxVec3& v)
    {
        if (PxAbs(v.x) > 1e-6f || PxAbs(v.y) > 1e-6f || PxAbs(v.z) > 1e-6f)
            return false;
        return true;
    }
 
}  // namespace Gu
 
}
 
#endif