checkerboard.h

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/*
    pbrt source code Copyright(c) 1998-2010 Matt Pharr and Greg Humphreys.

    This file is part of pbrt.

    pbrt is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.  Note that the text contents of
    the book "Physically Based Rendering" are *not* licensed under the
    GNU GPL.

    pbrt is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.

 */

#if defined(_MSC_VER)
#pragma once
#endif

#ifndef PBRT_TEXTURES_CHECKERBOARD_H
#define PBRT_TEXTURES_CHECKERBOARD_H

// textures/checkerboard.h*
#include "pbrt.h"
#include "texture.h"
#include "paramset.h"
#include "montecarlo.h"
#include "shape.h"
#include "parallel.h"
#include "progressreporter.h"

// CheckerboardTexture Declarations
template <typename T> class Checkerboard2DTexture : public Texture<T> {
public:
    // Checkerboard2DTexture Public Methods
    Checkerboard2DTexture(TextureMapping2D *m, Reference<Texture<T> > c1,
                          Reference<Texture<T> > c2, const string &aa)
        : mapping(m), tex1(c1), tex2(c2) {
        // Select antialiasing method for _Checkerboard2DTexture_
        if (aa == "none")             aaMethod = NONE;
        else if (aa == "closedform")  aaMethod = CLOSEDFORM;
        else {
            Warning("Antialiasing mode \"%s\" not understood by "
                    "Checkerboard2DTexture; using \"closedform\"", aa.c_str());
            aaMethod = CLOSEDFORM;
        }
    }
    ~Checkerboard2DTexture() {
        delete mapping;
    }
    T Evaluate(const DifferentialGeometry &dg) const {
        float s, t, dsdx, dtdx, dsdy, dtdy;
        mapping->Map(dg, &s, &t, &dsdx, &dtdx, &dsdy, &dtdy);
        if (aaMethod == NONE) {
            // Point sample _Checkerboard2DTexture_
            if ((Floor2Int(s) + Floor2Int(t)) % 2 == 0)
                return tex1->Evaluate(dg);
            return tex2->Evaluate(dg);
        }
        else {
            // Compute closed-form box-filtered _Checkerboard2DTexture_ value

            // Evaluate single check if filter is entirely inside one of them
            float ds = max(fabsf(dsdx), fabsf(dsdy));
            float dt = max(fabsf(dtdx), fabsf(dtdy));
            float s0 = s - ds, s1 = s + ds;
            float t0 = t - dt, t1 = t + dt;
            if (Floor2Int(s0) == Floor2Int(s1) && Floor2Int(t0) == Floor2Int(t1)) {
                // Point sample _Checkerboard2DTexture_
                if ((Floor2Int(s) + Floor2Int(t)) % 2 == 0)
                    return tex1->Evaluate(dg);
                return tex2->Evaluate(dg);
            }

            // Apply box filter to checkerboard region
#define BUMPINT(x) \
                (Floor2Int((x)/2) + \
                 2.f * max((x/2)-Floor2Int(x/2) - .5f, 0.f))
            float sint = (BUMPINT(s1) - BUMPINT(s0)) / (2.f * ds);
            float tint = (BUMPINT(t1) - BUMPINT(t0)) / (2.f * dt);
            float area2 = sint + tint - 2.f * sint * tint;
            if (ds > 1.f || dt > 1.f)
                area2 = .5f;
            return (1.f - area2) * tex1->Evaluate(dg) +
                   area2         * tex2->Evaluate(dg);
        }
    }
private:
    // Checkerboard2DTexture Private Data
    TextureMapping2D *mapping;
    Reference<Texture<T> > tex1, tex2;
    enum { NONE, CLOSEDFORM } aaMethod;
};


template <typename T> class Checkerboard3DTexture : public Texture<T> {
public:
    // Checkerboard3DTexture Public Methods
    Checkerboard3DTexture(TextureMapping3D *m, Reference<Texture<T> > c1,
                          Reference<Texture<T> > c2)
        : mapping(m), tex1(c1), tex2(c2) {
    }
    ~Checkerboard3DTexture() {
        delete mapping;
    }
    T Evaluate(const DifferentialGeometry &dg) const {
        Vector dpdx, dpdy;
        Point p = mapping->Map(dg, &dpdx, &dpdy);
        if ((Floor2Int(p.x) + Floor2Int(p.y) + Floor2Int(p.z)) % 2 == 0)
            return tex1->Evaluate(dg);
        else
            return tex2->Evaluate(dg);
    }
private:
    // Checkerboard3DTexture Private Data
    TextureMapping3D *mapping;
    Reference<Texture<T> > tex1, tex2;
};


Texture<float> *CreateCheckerboardFloatTexture(const Transform &tex2world,
        const TextureParams &tp);
Texture<Spectrum> *CreateCheckerboardSpectrumTexture(const Transform &tex2world,
        const TextureParams &tp);

#endif // PBRT_TEXTURES_CHECKERBOARD_H

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