103 lines
3.2 KiB
C++
103 lines
3.2 KiB
C++
/*
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This file is part of Mitsuba, a physically based rendering system.
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Copyright (c) 2007-2010 by Wenzel Jakob and others.
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Mitsuba is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License Version 3
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as published by the Free Software Foundation.
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Mitsuba is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <mitsuba/render/testcase.h>
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#include <mitsuba/core/shvector.h>
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MTS_NAMESPACE_BEGIN
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class TestSphericalHarmonics : public TestCase {
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public:
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MTS_BEGIN_TESTCASE()
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MTS_DECLARE_TEST(test01_shRotation)
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MTS_DECLARE_TEST(test02_shSampler)
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MTS_END_TESTCASE()
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void test01_shRotation() {
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/* Generate a random SH expansion, rotate it and
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spot-check 100 times against the original */
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ref<Random> random = new Random();
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int bands = 8;
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SHVector vec1(bands);
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for (int l=0; l<bands; ++l)
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for (int m=-l; m<=l; ++m)
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vec1(l, m) = random->nextFloat();
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Vector axis(squareToSphere(Point2(random->nextFloat(), random->nextFloat())));
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Transform trafo = Transform::rotate(axis, random->nextFloat()*360);
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Transform inv = trafo.inverse();
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SHRotation rot(vec1.getBands());
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SHVector::rotation(trafo, rot);
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SHVector vec2(bands);
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rot(vec1, vec2);
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for (int i=0; i<100; ++i) {
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Vector dir1(squareToSphere(Point2(random->nextFloat(), random->nextFloat()))), dir2;
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trafo(dir1, dir2);
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Float value1 = vec1.eval(dir2);
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Float value2 = vec2.eval(dir1);
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assertEquals(value1, value2);
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}
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}
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struct ClampedCos {
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Vector axis;
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ClampedCos(Vector axis) : axis(axis) { }
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Float operator()(const Vector &w) const { return std::max((Float) 0, dot(w, axis)); }
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};
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void test02_shSampler() {
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/* Draw 100 samples from a SH expansion of a clamped cosine-shaped
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distribution and verify the returned probabilities */
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int bands = 13, numSamples = 100, depth = 12;
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Vector v = normalize(Vector(1, 2, 3));
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ref<Random> random = new Random();
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SHVector clampedCos = SHVector(bands);
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clampedCos.project(ClampedCos(v), numSamples);
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//Float clampedCosError = clampedCos.l2Error(ClampedCos(v), numSamples);
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clampedCos.normalize();
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//cout << "Projection error = " << clampedCosError << endl;
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//cout << "Precomputing mip-maps" << endl;
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ref<SHSampler> sampler = new SHSampler(bands, depth);
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//cout << "Done: "<< sampler->toString() << endl;
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Float accum = 0;
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int nsamples = 100, nInAvg = 0;
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for (int i=0; i<=nsamples; ++i) {
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Point2 sample(random->nextFloat(), random->nextFloat());
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Float pdf1 = sampler->warp(clampedCos, sample);
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Float pdf2 = dot(v, sphericalDirection(sample.x, sample.y))/M_PI;
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Float relerr = std::abs(pdf1-pdf2)/pdf2;
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if (pdf2 > 0.01) {
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accum += relerr; ++nInAvg;
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assertTrue(relerr < 0.08);
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}
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}
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assertTrue(accum / nInAvg < 0.01);
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}
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};
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MTS_EXPORT_TESTCASE(TestSphericalHarmonics, "Testcase for Spherical Harmonics code")
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MTS_NAMESPACE_END
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