EUC_Expression.C

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/*
 * Copyright (c) 2024
 *      Side Effects Software Inc.  All rights reserved.
 *
 * Redistribution and use of Houdini Development Kit samples in source and
 * binary forms, with or without modification, are permitted provided that the
 * following conditions are met:
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 *    this list of conditions and the following disclaimer.
 * 2. The name of Side Effects Software may not be used to endorse or
 *    promote products derived from this software without specific prior
 *    written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY SIDE EFFECTS SOFTWARE `AS IS' AND ANY EXPRESS
 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN
 * NO EVENT SHALL SIDE EFFECTS SOFTWARE BE LIABLE FOR ANY DIRECT, INDIRECT,
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 *----------------------------------------------------------------------------
 * Defines the expressions that can be performed on sets of
 * euclidean objects.
 */

#include "EUC_Expression.h"

#include <SYS/SYS_Math.h>
#include <UT/UT_Vector3.h>
#include <UT/UT_RootFinder.h>

using namespace HDK_Sample;

EUC_ExpressionList EUC_Expression::ourExpressionList;
int                EUC_Expression::ourEvaluateTime = 0;

//
// EUC_Expression
// 
EUC_Expression::EUC_Expression()
{
    myRefCount = 0;
    myUid = ourExpressionList.size();
    myLastEvaluateTime = 0;
    myCd = 1;
    myVisible = true;
    ourExpressionList.append(this);
}

EUC_Expression::~EUC_Expression()
{
    // Eliminate ourselves from the expression list.
    ourExpressionList(getUid()) = 0;
}

void
EUC_Expression::addRef()
{
    myRefCount++;
}

void
EUC_Expression::removeRef()
{
    myRefCount--;
    if (myRefCount <= 0)
        delete this;
}

EUC_Expression *
EUC_Expression::getExprFromUid(int uid)
{
    // Out of bound is not created.
    if (uid < 0 || uid >= ourExpressionList.size())
        return 0;

    return ourExpressionList(uid);
}

void
EUC_Expression::setLook(bool visible, const UT_Vector3 &cd)
{
    myVisible = visible;
    myCd = cd;
}

void
EUC_Expression::applyLook(EUC_Object *obj)
{
    obj->setLook(myVisible, myCd);
}

void
EUC_Expression::evaluate(EUC_ObjectList &results)
{
    // Reset the global evaluate time so we clear all the caches.
    ourEvaluateTime++;

    // Call the recursive evaluate.  User wants total number of objects.
    EUC_ObjectList              tmp;

    evaluateRecurse(tmp, results);
}

void
EUC_Expression::evaluateRecurse(EUC_ObjectList &result,
                                EUC_ObjectList &totalobj)
{
    // Check to see if we are already cached.
    if (myLastEvaluateTime == ourEvaluateTime)
    {
        result = myObjectCache;
        return;
    }
    // Call subclass & cache.
    myLastEvaluateTime = ourEvaluateTime;
    myObjectCache.setSize(0);
    evaluateSubclass(myObjectCache, totalobj);
    result = myObjectCache;
}

//
// EUC_ExprPoint
//
EUC_ExprPoint::EUC_ExprPoint(const UT_Vector2 &pos) : EUC_Expression()
{
    myPos = pos;
}

void
EUC_ExprPoint::evaluateSubclass(EUC_ObjectList &result,
                                EUC_ObjectList &totalobj)
{
    EUC_Point   *pt;

    pt = new EUC_Point(myPos);
    applyLook(pt);
    result.setSize(0);
    result.append(pt);
    totalobj.append(pt);
}

//
// EUC_ExprPointFromObject
//
EUC_ExprPointFromObject::EUC_ExprPointFromObject(EUC_Expression *src, int idx) : EUC_Expression()
{
    src->addRef();
    mySource = src;
    myIndex = idx;
}

EUC_ExprPointFromObject::~EUC_ExprPointFromObject()
{
    mySource->removeRef();
}

void
EUC_ExprPointFromObject::evaluateSubclass(EUC_ObjectList &result,
                                EUC_ObjectList &totalobj)
{
    EUC_Point           *pt;
    EUC_ObjectList       objlist;
    EUC_Object          *obj;
    int                  i, n;
    UT_Vector2           pos;
    bool                 haspos;

    result.setSize(0);
    mySource->evaluateRecurse(objlist, totalobj);
    n = objlist.size();
    for (i = 0; i < n; i++)
    {
        obj = objlist(i);
        haspos = false;
        switch (obj->getType())
        {
            case EUC_PointType:
                if (myIndex == 0)
                {
                    haspos = true;
                    pos = ((EUC_Point *)obj)->getPos();
                }
                break;
            case EUC_LineType:
            case EUC_CircleType:
                if (myIndex >= 0 && myIndex <= 1)
                {
                    haspos = true;
                    pos = ((EUC_Line *)obj)->getPt(myIndex);
                }
                break;
        }

        if (haspos)
        {
            pt = new EUC_Point(pos);
            applyLook(pt);
            result.append(pt);
            totalobj.append(pt);
        }
    }
}

//
// EUC_ExprLineFromPoints
//
EUC_ExprLineFromPoints::EUC_ExprLineFromPoints(EUC_Expression *pta, EUC_Expression *ptb) : EUC_Expression()
{
    pta->addRef();
    ptb->addRef();
    myPtA = pta;
    myPtB = ptb;
}

EUC_ExprLineFromPoints::~EUC_ExprLineFromPoints()
{
    myPtA->removeRef();
    myPtB->removeRef();
}

void
EUC_ExprLineFromPoints::evaluateSubclass(EUC_ObjectList &result,
                                EUC_ObjectList &totalobj)
{
    EUC_Line            *line;
    EUC_ObjectList       ptalist, ptblist;
    int                  i, n;
    UT_Vector2           a, b;

    result.setSize(0);
    myPtA->evaluateRecurse(ptalist, totalobj);
    myPtB->evaluateRecurse(ptblist, totalobj);
    n = SYSmin(ptalist.size(), ptblist.size());
    for (i = 0; i < n; i++)
    {
        if (ptalist(i)->getType() == EUC_PointType &&
            ptblist(i)->getType() == EUC_PointType)
        {
            a = ((EUC_Point *)ptalist(i))->getPos();
            b = ((EUC_Point *)ptblist(i))->getPos();
            line = new EUC_Line();
            applyLook(line);
            line->setPt(0, a);
            line->setPt(1, b);
            result.append(line);
            totalobj.append(line);
        }
    }
}

//
// EUC_ExprCircleFromPoints
//
EUC_ExprCircleFromPoints::EUC_ExprCircleFromPoints(EUC_Expression *center, EUC_Expression *pt) : EUC_Expression()
{
    center->addRef();
    pt->addRef();
    myCenter = center;
    myPoint = pt;
}

EUC_ExprCircleFromPoints::~EUC_ExprCircleFromPoints()
{
    myCenter->removeRef();
    myPoint->removeRef();
}

void
EUC_ExprCircleFromPoints::evaluateSubclass(EUC_ObjectList &result,
                                EUC_ObjectList &totalobj)
{
    EUC_Circle          *circle;
    EUC_ObjectList       ptalist, ptblist;
    int                  i, n;
    UT_Vector2           a, b;

    result.setSize(0);
    myCenter->evaluateRecurse(ptalist, totalobj);
    myPoint->evaluateRecurse(ptblist, totalobj);
    n = SYSmin(ptalist.size(), ptblist.size());
    for (i = 0; i < n; i++)
    {
        if (ptalist(i)->getType() == EUC_PointType &&
            ptblist(i)->getType() == EUC_PointType)
        {
            a = ((EUC_Point *)ptalist(i))->getPos();
            b = ((EUC_Point *)ptblist(i))->getPos();
            circle = new EUC_Circle();
            applyLook(circle);
            circle->setPt(0, a);
            circle->setPt(1, b);
            result.append(circle);
            totalobj.append(circle);
        }
    }
}

//
// EUC_ExprIntersect
//
EUC_ExprIntersect::EUC_ExprIntersect(EUC_Expression *expra, EUC_Expression *exprb) : EUC_Expression()
{
    expra->addRef();
    exprb->addRef();
    myExprA = expra;
    myExprB = exprb;
}

EUC_ExprIntersect::~EUC_ExprIntersect()
{
    myExprA->removeRef();
    myExprB->removeRef();
}

void
EUC_ExprIntersect::evaluateSubclass(EUC_ObjectList &result,
                                EUC_ObjectList &totalobj)
{
    EUC_Point           *pt;
    EUC_ObjectList       ptalist, ptblist;
    EUC_Object          *obja, *objb;
    int                  i, n;
    UT_Vector2           pos;

    result.setSize(0);
    myExprA->evaluateRecurse(ptalist, totalobj);
    myExprB->evaluateRecurse(ptblist, totalobj);
    n = SYSmin(ptalist.size(), ptblist.size());
    for (i = 0; i < n; i++)
    {
        // Sort the types so lowest is obja.
        if (ptalist(i)->getType() < ptblist(i)->getType())
        {
            obja = ptalist(i);
            objb = ptblist(i);
        }
        else
        {
            objb = ptalist(i);
            obja = ptblist(i);
        }

        // This simplifies this double-switch...
        if (obja->getType() == EUC_PointType)
        {
            // Points never intersect anything.
            continue;
        }

        if (obja->getType() == EUC_LineType)
        {
            // Either Line-Line or Line-Circle
            if (objb->getType() == EUC_LineType)
            {
                // Line-Line intersection
                UT_Vector3              p1, p2, v1, v2, isect;
                int                     retcode;

                pos = ((EUC_Line *)obja)->getPt(0);
                p1.assign(pos.x(), pos.y(), 0);
                pos = ((EUC_Line *)obja)->getPt(1);
                v1.assign(pos.x(), pos.y(), 0);
                v1 -= p1;
                
                pos = ((EUC_Line *)objb)->getPt(0);
                p2.assign(pos.x(), pos.y(), 0);
                pos = ((EUC_Line *)objb)->getPt(1);
                v2.assign(pos.x(), pos.y(), 0);
                v2 -= p2;

                retcode = isect.lineIntersect(p1, v1, p2, v2);
                // Non-parallel lines get a single intersection.
                if (retcode != -1)
                {
                    pos = isect;
                    pt = new EUC_Point(pos);
                    applyLook(pt);
                    result.append(pt);
                    totalobj.append(pt);
                }
            }
            else
            {
                // Line-Circle isect.
                UT_Vector2              p, v, center;
                float                   radius, a, b, c, t0, t1;
                
                // x = p.x + v.x * t
                // y = p.y + v.y * t
                // Solve for:
                // (x - c.x)^2 + (y - c.y) ^ 2 = r^2
                // (v.x*t + (p.x - c.x))^2 + (v.y*t + (p.y - c.y))^2 = r^2
                // Let c = p - c
                // (v.x^2+v.y^2)*t^2 
                //   + 2*(v.x*c.x+v.y*c.y)*t 
                //   + (c.x^2+c.y^2-r^2) = 0
                // 

                p = ((EUC_Line *)obja)->getPt(0);
                v = ((EUC_Line *)obja)->getPt(1);
                v -= p;

                center = ((EUC_Circle *)objb)->getCenter();
                radius = ((EUC_Circle *)objb)->getRadius();

                center = p - center;
                a = dot(v, v);
                b = 2 * dot(v, center);
                c = dot(center, center) - radius*radius;
                if (UT_RootFinder::quadratic(a, b, c, t0, t1))
                {
                    // We consider it two intersections.
                    pos = p + t0 * v;
                    pt = new EUC_Point(pos);
                    applyLook(pt);
                    result.append(pt);
                    totalobj.append(pt);

                    pos = p + t1 * v;
                    pt = new EUC_Point(pos);
                    applyLook(pt);
                    result.append(pt);
                    totalobj.append(pt);
                }
            }
        }
        else
        {
            // Must be Circle-Circle.
            // Along the line between the centers, parameterized
            // with arclength with t, height one one circle is
            // hA(t)^2 = rA^2 - t^2
            // Height on the other circle, where distance between them is d,
            // hB(t)^2 = rB^2 - (t-d)^2
            // We want hA == hB.  
            // We thus get
            // rA^2 - t^2 = rB^2 - t^2 + 2td - d^2
            // 2td = (rA^2 - rB^2 + d^2)
            // t = (rA^2 - rB^2 + d^2) / 2d
            // We can then sanity test t & directly compute the intersection.
            float               rA, rB, t, d, hA2, hB2;
            UT_Vector2          cA, cB, v, perpv;

            rA = ((EUC_Circle *)obja)->getRadius();
            cA = ((EUC_Circle *)obja)->getCenter();
            rB = ((EUC_Circle *)objb)->getRadius();
            cB = ((EUC_Circle *)objb)->getCenter();
            v = cB;
            v -= cA;
            d = v.length();
            v.normalize();
            if (!SYSequalZero(d))
            {
                // Non-zero difference, a chance for intersection.
                t = (rA*rA - rB*rB + d*d) / (2.0 * d);

                // Make sure neither of the squared heights are negative.
                hA2 = rA*rA - t*t;
                hB2 = rB*rB - (t-d)*(t-d);
                if (hA2 >= 0 && hB2 >= 0)
                {
                    // Get the perpindicular
                    perpv.x() = v.y();
                    perpv.y() = -v.x();

                    hA2 = SYSsqrt(hA2);
                    
                    // Compute our new positions.
                    pos = cA + t * v + hA2 * perpv;
                    pt = new EUC_Point(pos);
                    applyLook(pt);
                    result.append(pt);
                    totalobj.append(pt);

                    pos = cA + t * v - hA2 * perpv;
                    pt = new EUC_Point(pos);
                    applyLook(pt);
                    result.append(pt);
                    totalobj.append(pt);
                }
            }
        }
    }
}

//
// EUC_ExprSelect
//
EUC_ExprSelect::EUC_ExprSelect(EUC_Expression *src, int idx) : EUC_Expression()
{
    src->addRef();
    mySource = src;
    myIndex = idx;
}

EUC_ExprSelect::~EUC_ExprSelect()
{
    mySource->removeRef();
}

void
EUC_ExprSelect::evaluateSubclass(EUC_ObjectList &result,
                                EUC_ObjectList &totalobj)
{
    EUC_ObjectList       objlist;

    result.setSize(0);
    mySource->evaluateRecurse(objlist, totalobj);

    if (myIndex >= 0 && myIndex < objlist.size())
        result.append(objlist(myIndex));
}