SOP/SOP_SParticle.h

/*
 * Copyright (c) 2025
 *      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:
 * 1. Redistributions of source code must retain the above copyright notice,
 *    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,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
 * OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 *----------------------------------------------------------------------------
 * This is a simple particle system...  Not too much to it, but this can be
 * used as a template for your own...
 */


#ifndef __SOP_SParticle_h__
#define __SOP_SParticle_h__

#include <SOP/SOP_Node.h>

#define INT_PARM(name, idx, vidx, t)    \
            return evalInt(name, &myOffsets[idx], vidx, t);

#define FLT_PARM(name, idx, vidx, t)    \
            return evalFloat(name, &myOffsets[idx], vidx, t);

class GEO_ParticleVertex;
class GEO_PrimParticle;
class GU_RayIntersect;

namespace HDK_Sample {
class SOP_SParticle : public SOP_Node
{
public:
             SOP_SParticle(OP_Network *net, const char *name, OP_Operator *op);
            ~SOP_SParticle() override;

    static PRM_Template          myTemplateList[];
    static OP_Node              *myConstructor(OP_Network*, const char *,
                                                            OP_Operator *);

protected:
    const char         *inputLabel(OP_InputIdx idx) const override;

    void                birthParticle();
    int                 moveParticle(GA_Offset ptoff,
                                     const UT_Vector3 &force);

    void                initSystem();
    void                timeStep(fpreal now);

    // Method to cook geometry for the SOP
    OP_ERROR            cookMySop(OP_Context &context) override;

private:
    // These use defines to make it easy to add parms and remove them.
    // The evaluation routines use the indexed name lookup which is quite
    //  fast, yet easy to change indices (since the order of the indices
    //  doesn't have to be in sequential order...
    int                  RESET()        { INT_PARM("reset", 0, 0, 0) }
    int                  BIRTH(fpreal t){ INT_PARM("birth", 2, 0, t) }
    fpreal               FX(fpreal t)   { FLT_PARM("force", 1, 0, t) }
    fpreal               FY(fpreal t)   { FLT_PARM("force", 1, 1, t) }
    fpreal               FZ(fpreal t)   { FLT_PARM("force", 1, 2, t) }

    const GU_Detail     *mySource;
    GA_Index             mySourceNum;           // Source point to birth from
    GA_ROHandleV3        mySourceVel;           // Velocity attrib in source

    GU_RayIntersect     *myCollision;

    GEO_PrimParticle    *mySystem;
    fpreal               myLastCookTime;        // Last cooked time
    GA_RWHandleV3        myVelocity;            // My velocity attribute
    GA_RWHandleF         myLife;                // My life attribute

    static int          *myOffsets;
};
} // End HDK_Sample namespace

#endif