RAY_DemoMountain.C

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/*
 * 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
 */

#include "RAY_DemoMountain.h"
#include <UT/UT_DSOVersion.h>
#include <GU/GU_Detail.h>
#include <GU/GU_PrimPoly.h>
#include <RAY/RAY_ProceduralFactory.h>

using namespace HDK_Sample;

#define MAX_SPLITS      8

#define UT_DEBUG        1
#include <UT/UT_Counter.h>
static UT_Counter       theCount("Mountains");
static UT_Counter       theTotal("TotalMountains");

static RAY_ProceduralArg        theArgs[] = {
    RAY_ProceduralArg("p0",     "real", "-1 -1 0"),
    RAY_ProceduralArg("p1",     "real", " 1 -1 0"),
    RAY_ProceduralArg("p2",     "real", " 0  1 0"),
    RAY_ProceduralArg()
};

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

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

RAY_DemoMountain::RAY_DemoMountain(int splits)
    : mySplits(splits)
{
    theCount++;
    theTotal++;
}

RAY_DemoMountain::~RAY_DemoMountain()
{
    theCount--;
}

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

int
RAY_DemoMountain::initialize(const UT_BoundingBox *)
{
    uint                seed = 0xbabecafe;

    myP[0].assign(-1, -1, 0, seed);
    SYSfastRandom(seed);                // Permute seed
    myP[1].assign( 1, -1, 0, seed);
    SYSfastRandom(seed);                // Permute seed
    myP[2].assign( 0, -1, 0, seed);

    // Get parameter values
    import("p0", myP[0].pos.data(), 3);
    import("p1", myP[1].pos.data(), 3);
    import("p2", myP[2].pos.data(), 3);
    return 1;
}

void
RAY_DemoMountain::computeBounds(UT_BoundingBox &box, bool include_displace)
{
    box.initBounds(myP[0].pos);
    box.enlargeBounds(myP[1].pos);
    box.enlargeBounds(myP[2].pos);
    if (include_displace)
    {
        fpreal  bounds = 0.5 / (fpreal)mySplits;
        box.expandBounds(0, bounds);
    }
}


void
RAY_DemoMountain::getBoundingBox(UT_BoundingBox &box)
{
    computeBounds(box, true);
    fpreal      bounds = 0.5 / (fpreal)mySplits;
    box.initBounds(myP[0].pos);
    box.enlargeBounds(myP[1].pos);
    box.enlargeBounds(myP[2].pos);
    box.expandBounds(0, bounds);
}

void
RAY_DemoMountain::render()
{
    fpreal               lod;
    UT_BoundingBox       box;

    // Invoke the measuring code on the bounding box to determine the level of
    // detail.  The level of detail is the square root of the number of pixels
    // covered by the bounding box (with all shading factors considered).
    // However, for computing LOD, we do *not* want to include displacement
    // bounds
    computeBounds(box, false);
    lod = getLevelOfDetail(box);

    if (lod < 6 || mySplits > MAX_SPLITS)
    {
        // Render geometry
        fractalRender();
    }
    else
    {
        // Split into child procedurals
        fractalSplit();
    }
}

static void
edgeSplit(FractalPoint &P, const FractalPoint &p0, const FractalPoint &p1,
                fpreal scale)
{
    uint        seed;
    fpreal      disp;
    
    seed = (p0.seed + p1.seed)/2;
    disp = SYSfastRandomZero(seed)*scale;
    P.seed = seed;
    P.pos = (p0.pos + p1.pos) * .5;
    P.pos(2) += 0.25 * disp * distance3d(p0.pos, p1.pos);
}

void
RAY_DemoMountain::fractalSplit()
{
    RAY_DemoMountain    *kids[4];
    int                  i;
    fpreal               scale;

    scale = 1.0 / (fpreal)mySplits;
    for (i = 0; i < 4; i++)
        kids[i] = new RAY_DemoMountain(mySplits+1);

    for (i = 0; i < 3; i++)
    {
        kids[i]->myP[0] = myP[i];
        edgeSplit(kids[i]->myP[1], myP[i], myP[(i+1)%3], scale);
    }
    for (i = 0; i < 3; i++)
    {
        kids[3]->myP[i] = kids[(i+1)%3]->myP[2] = kids[i]->myP[1];
    }
    for (i = 0; i < 4; i++)
    {
        RAY_ProceduralChildPtr  child = createChild();
        child->addProcedural(kids[i]);
    }
}

void
RAY_DemoMountain::fractalRender()
{
    // Build some geometry
    RAY_ProceduralGeo    geo = createGeometry();
    GU_PrimPoly         *poly = GU_PrimPoly::build(geo.get(), 3);

#if 0
    // Optionally, create a primitive color attribute "Cd"
    uint seed = myP[0].seed + myP[1].seed + myP[2].seed;
    UT_Vector3 clr;
    clr.x() = SYSfastRandom(seed);
    clr.y() = SYSfastRandom(seed);
    clr.z() = SYSfastRandom(seed);
    GA_RWHandleV3 Cd(geo->addDiffuseAttribute(GA_ATTRIB_PRIMITIVE));
    Cd.set(poly->getMapOffset(), clr);
#endif

    for (int i = 0; i < 3; i++)
    {
        geo->setPos3(poly->getPointOffset(i), myP[i].pos);
    }

    // Now, add the geometry to mantra.
    RAY_ProceduralChildPtr      child = createChild();
    child->addGeometry(geo);
}