RAY/RAY_DemoGT.C

/*
 * 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 sample procedural DSO
 */

#undef UT_ASSERT_LEVEL
#define UT_ASSERT_LEVEL 4

#include <UT/UT_DSOVersion.h>
#include <UT/UT_MTwister.h>
#include <UT/UT_StackBuffer.h>
#include <RAY/RAY_ProcGT.h>
#include <GT/GT_PrimitiveBuilder.h>
#include <GT/GT_PrimCurveMesh.h>
#include "RAY_DemoGT.h"
#include <RAY/RAY_ProceduralFactory.h>

using namespace HDK_Sample;

// Sample definition in an IFD
// ray_procedural -m -1 -.1 -1 -M 1 .1 1 demogt debug 0 count 10000 segments 2

static RAY_ProceduralArg        theArgs[] = {
    RAY_ProceduralArg("maxradius",      "real",         "0.01"),
    RAY_ProceduralArg("count",          "int",          "100"),
    RAY_ProceduralArg("segments",       "int",          "1"),
    RAY_ProceduralArg("debug",          "int",          "0"),
    RAY_ProceduralArg()
};

class ProcDef : public RAY_ProceduralFactory::ProcDefinition
{
public:
    ProcDef()
        : RAY_ProceduralFactory::ProcDefinition("demogt")
    {
    }
    RAY_Procedural      *create() const override { return new RAY_DemoGT(); }
    RAY_ProceduralArg   *arguments() const override { return theArgs; }
};

void
registerProcedural(RAY_ProceduralFactory *factory)
{
    factory->insert(new ProcDef);
}

RAY_DemoGT::RAY_DemoGT()
    : myMaxRadius(0.05)
    , myCurveCount(0)
    , mySegments(1)
    , myDebug(false)
{
    myBox.initBounds(0, 0, 0);
}

RAY_DemoGT::~RAY_DemoGT()
{
}

const char *
RAY_DemoGT::className() const
{
    return "RAY_DemoGT";
}

int
RAY_DemoGT::initialize(const UT_BoundingBox *box)
{
    if (box)
        myBox = *box;
    else
        myBox = UT_BoundingBox(-1, -1, -1, 1, 1, 1);
    
    // Import the number of motion segments
    if (!import("segments", &mySegments, 1))
        mySegments = 1;

    if (!import("count", &myCurveCount, 1))
        myCurveCount = 100;

    if (!import("maxradius", &myMaxRadius, 1))
        myMaxRadius = 0.05;

    int         ival;
    if (import("debug", &ival, 1))
        myDebug = (ival != 0);

    if (myDebug)
        return true;
    // Only need to render if there's geometry to render
    return myCurveCount > 0 && mySegments > 0 && myMaxRadius > 0;
}

void
RAY_DemoGT::getBoundingBox(UT_BoundingBox &box)
{
    box = myBox;

    // Now, expand bounds to include the maximum radius of a curve
    box.expandBounds(0, myMaxRadius);
}

static GT_PrimitiveHandle
makeCurveMesh(const UT_BoundingBox &box,
        int ncurves,
        fpreal maxradius,
        int segments)
{
    static const int                     pts_per_curve = 4;
    UT_MersenneTwister                   twist;
    GT_Real16Array                      *f16;
    int                                  npts = ncurves * pts_per_curve;

    // Allocate colors as uniform fpreal16 data
    GT_DataArrayHandle                   clr;
    f16 = new GT_Real16Array(ncurves, 3, GT_TYPE_COLOR);
    for (int i = 0; i < ncurves*3; ++i)
        f16->data()[i] = twist.frandom();

    clr.reset(f16);

    // Allocate widths as per-point fpreal16 data
    GT_DataArrayHandle                   widths;
    f16 = new GT_Real16Array(npts, 1);
    for (int curve = 0; curve < ncurves; curve++)
    {
        fpreal16        *val = f16->data() + pts_per_curve * curve;
        fpreal           width = SYSlerp(maxradius, maxradius*.1,
                                        fpreal(twist.frandom())) * 2;
        for (int pt = 0; pt < pts_per_curve; ++pt)
        {
            val[pt] = width;
            width *= .7;        // Taper each curve
        }
    }
    widths.reset(f16);

    // Allocate "P" as per-point fpreal32 data
    UT_StackBuffer<GT_DataArrayHandle>   P(segments);   // One for each segment
    UT_StackBuffer<GT_Real32Array *>     Pdata(segments);
    UT_StackBuffer<fpreal>               Py(pts_per_curve);
    for (int i = 0; i < segments; ++i)
    {
        Pdata[i] = new GT_Real32Array(npts, 3, GT_TYPE_POINT);
        P[i] = Pdata[i];
    }

    for (int i = 0; i < pts_per_curve; ++i)
    {
        fpreal  fity = fpreal(i)/(pts_per_curve-1);
        Py[i] = SYSlerp((fpreal)box.ymin(), (fpreal)box.ymax(), fity);
    }

    // Now, set positions
    for (int curve = 0; curve < ncurves; ++curve)
    {
        fpreal  tx = SYSlerp(.1, .9, twist.frandom());
        fpreal  tz = SYSlerp(.1, .9, twist.frandom());
        for (int seg = 0; seg < segments; ++seg)
        {
            fpreal      px, pz;
            fpreal      vx, vz;
            px = SYSlerp(box.xmin(), box.xmax(), tx);
            pz = SYSlerp(box.zmin(), box.zmax(), tz);

            // Choose a different velocity trajectory per motion segment
            vx = SYSlerp(0.0, box.xsize()*.1/segments, twist.frandom()-.5);
            vz = SYSlerp(0.0, box.zsize()*.1/segments, twist.frandom()-.5);

            // Choose a different height per motion segment
            fpreal      height = SYSlerp(.5, 1.0, twist.frandom());
            int off = curve * pts_per_curve * 3;
            for (int pt = 0; pt < pts_per_curve; ++pt)
            {
                Pdata[seg]->data()[off+pt*3+0] = px;
                Pdata[seg]->data()[off+pt*3+1] = Py[pt] * height;
                Pdata[seg]->data()[off+pt*3+2] = pz;
                UT_ASSERT(px >= box.xmin() && px < box.xmax());
                UT_ASSERT(pz >= box.zmin() && pz < box.zmax());
                px += vx;
                pz += vz;
                vx *= .4;
                vz *= .4;
            }
        }
    }
    // Debug the P values
    //P[0]->dumpValues("P");

    // Now we have all the data arrays, we can build the curve
    GT_AttributeMap     *amap;
    GT_AttributeList    *uniform;
    GT_AttributeList    *vertex;

    // First, create the uniform attributes
    amap = new GT_AttributeMap();
    amap->add("Cd", true);
    uniform = new GT_AttributeList(amap, segments);     // 2 motion segments
    for (int seg = 0; seg < segments; ++seg)
        uniform->set(0, clr, seg);      // Share color data for segment

    // Now, create the per-vertex attributes
    amap = new GT_AttributeMap();
    amap->add("P", true);
    amap->add("width", true);
    vertex = new GT_AttributeList(amap, segments);
    for (int seg = 0; seg < segments; ++seg)
    {
        vertex->set(0, P[seg], seg);    // Set P for the motion segment
        vertex->set(1, widths, seg);    // Share width data
    }

    // Create the vertex per curve counts
    GT_DataArrayHandle  vertex_counts;
    vertex_counts.reset(new GT_IntConstant(ncurves, pts_per_curve));

    // Create a new curve mesh
    GT_PrimitiveHandle prim(new GT_PrimCurveMesh(GT_BASIS_LINEAR,
                                vertex_counts,
                                GT_AttributeListHandle(vertex),
                                GT_AttributeListHandle(uniform),
                                GT_AttributeListHandle(),
                                false));

    // Debug the curve primitive
    //prim->dumpPrimitive();
    return prim;
}

static GT_PrimitiveHandle
testBox(const UT_BoundingBox &box, fpreal32 maxwidth)
{
    GT_BuilderStatus    err;
    GT_PrimitiveHandle  prim;
    fpreal16            clr[3] = { .3f, .5f, 1.f };
    prim = GT_PrimitiveBuilder::wireBox(err, box,
            GT_VariadicAttributes()
                << GT_Attribute("constant fpreal32 width", &maxwidth)
                << GT_Attribute("constant color16 Cd", clr)
        );
    return prim;
}

void
RAY_DemoGT::render()
{
    // To render this procedural, we create a new GT procedural as a child
    RAY_ProceduralChildPtr      obj = createChild();

    GT_PrimitiveHandle  prim;
    if (myDebug)
        prim = testBox(myBox, myMaxRadius*2);
    else
    {
        int                             one = 1;
        prim = makeCurveMesh(myBox, myCurveCount, myMaxRadius, mySegments);

        // Turn on subdivision curve rendering
        obj->changeSetting("object:rendersubdcurves", 1, &one);
    }
    int zero;
    obj->changeSetting("geometry:computeN", 1, &zero);

    // Add the child procedural
    obj->addProcedural(new RAY_ProcGT(prim));
}