[2853] | 1 | #include "common.h"
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| 2 | #include "SampleGenerator.h"
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| 3 |
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[2901] | 4 |
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[2853] | 5 | using namespace std;
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| 6 |
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[2901] | 7 | HaltonSequence SphericalSampleGenerator::sHalton;
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| 8 | HaltonSequence PoissonDiscSampleGenerator::sHalton;
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| 9 | HaltonSequence GaussianSampleGenerator::sHalton;
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[2902] | 10 | HaltonSequence PseudoRandomGenerator::sHalton;
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[2853] | 11 |
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[2901] | 12 |
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[2853] | 13 | SampleGenerator::SampleGenerator(int numSamples, float radius):
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| 14 | mNumSamples(numSamples), mRadius(radius)
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| 15 | {}
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| 16 |
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| 17 |
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| 18 | PoissonDiscSampleGenerator::PoissonDiscSampleGenerator(int numSamples, float radius):
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| 19 | SampleGenerator(numSamples, radius)
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| 20 | {}
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| 21 |
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| 22 |
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[2900] | 23 | void PoissonDiscSampleGenerator::Generate(float *samples) const
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[2853] | 24 | {
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[2873] | 25 | // this is a hacky poisson sampling generator which does random dart-throwing
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| 26 | // until it is not able to place any dart for a number of tries
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| 27 | // in this case, the required min distance is reduced
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| 28 | // the solution is a possion sampling with respect to the adjusted min distance
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| 29 | // better solutions have been proposed, i.e., using hierarchical sampling
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| 30 |
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| 31 | const float maxTries = 1000;
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| 32 | const float f_reduction = 0.9f;
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| 33 |
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[2853] | 34 | static HaltonSequence halton;
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| 35 | float r[2];
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| 36 |
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| 37 | // generates poisson distribution on disc
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[2873] | 38 | float minDist = 2.0f / sqrt((float)mNumSamples);
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[2853] | 39 |
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| 40 | //cout << "minDist before= " << minDist << endl;
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[2900] | 41 | Sample2 *s = (Sample2 *)samples;
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[2853] | 42 |
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| 43 | for (int i = 0; i < mNumSamples; ++ i)
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| 44 | {
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| 45 | int tries = 0, totalTries = 0;
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| 46 |
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| 47 | // repeat until valid sample was found
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| 48 | while (1)
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| 49 | {
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| 50 | ++ tries;
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| 51 | ++ totalTries;
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| 52 |
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| 53 | halton.GetNext(2, r);
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| 54 |
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| 55 | const float rx = r[0] * 2.0f - 1.0f;
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| 56 | const float ry = r[1] * 2.0f - 1.0f;
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| 57 |
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| 58 | // check if in disk, else exit early
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| 59 | if (rx * rx + ry * ry > 1)
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| 60 | continue;
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| 61 |
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| 62 | bool sampleValid = true;
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| 63 |
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| 64 | // check poisson property
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| 65 | for (int j = 0; ((j < i) && sampleValid); ++ j)
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| 66 | {
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| 67 | const float dist =
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[2900] | 68 | sqrt((s[j].x - rx) * (s[j].x - rx) +
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| 69 | (s[j].y - ry) * (s[j].y - ry));
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[2853] | 70 |
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| 71 | if (dist < minDist)
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| 72 | sampleValid = false;
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| 73 | }
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| 74 |
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| 75 | if (sampleValid)
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| 76 | {
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[2900] | 77 | s[i].x = rx;
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| 78 | s[i].y = ry;
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[2853] | 79 | break;
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| 80 | }
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| 81 |
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[2873] | 82 | if (tries > maxTries)
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[2853] | 83 | {
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[2873] | 84 | minDist *= f_reduction;
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[2853] | 85 | tries = 0;
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| 86 | }
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| 87 | }
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| 88 |
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| 89 | //cout << "sample: " << samples[i].x << " " << i << " " << samples[i].y << " r: " << sqrt(samples[i].x * samples[i].x + samples[i].y * samples[i].y) << " tries: " << totalTries << endl;
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| 90 | }
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| 91 |
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| 92 | //cout << "minDist after= " << minDist << endl;
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[2898] | 93 | }
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| 94 |
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| 95 |
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| 96 |
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| 97 | GaussianSampleGenerator::GaussianSampleGenerator(int numSamples, float radius):
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| 98 | SampleGenerator(numSamples, radius)
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| 99 | {}
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| 100 |
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| 101 |
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[2900] | 102 | void GaussianSampleGenerator::Generate(float *samples) const
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[2898] | 103 | {
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| 104 | float r[2];
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| 105 |
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| 106 | const float sigma = mRadius;
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| 107 |
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[2900] | 108 | Sample2 *s = (Sample2 *)samples;
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| 109 |
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[2898] | 110 | const float p0 = 1.0f / (sigma * sqrt(2.0f * M_PI));
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| 111 | const float p1 = 1.0f / (sigma * sqrt(2.0f * M_PI));
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| 112 |
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| 113 | for (int i = 0; i < mNumSamples; ++ i)
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| 114 | {
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[2901] | 115 | sHalton.GetNext(2, r);
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[2898] | 116 |
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| 117 | float exp_x = -(r[0] * r[0]) / (2.0f * sigma * sigma);
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| 118 | float exp_y = -(r[1] * r[1]) / (2.0f * sigma * sigma);
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| 119 |
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[2900] | 120 | s[i].x = p0 * pow(M_E, exp_x);
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| 121 | s[i].y = p1 * pow(M_E, exp_y);
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[2898] | 122 | }
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| 123 |
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| 124 | //cout << "minDist after= " << minDist << endl;
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[2899] | 125 | }
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| 126 |
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| 127 |
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[2902] | 128 | PseudoRandomGenerator::PseudoRandomGenerator(int numSamples, float radius):
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| 129 | SampleGenerator(numSamples, radius)
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| 130 | {}
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| 131 |
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| 132 |
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| 133 | void PseudoRandomGenerator::Generate(float *samples) const
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| 134 | {
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| 135 | sHalton.GetNext(2 * mNumSamples, samples);
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| 136 | }
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| 137 |
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| 138 |
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[2899] | 139 | SphericalSampleGenerator::SphericalSampleGenerator(int numSamples, float radius):
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| 140 | SampleGenerator(numSamples, radius)
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| 141 | {}
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| 142 |
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| 143 |
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[2900] | 144 | void SphericalSampleGenerator::Generate(float *samples) const
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[2899] | 145 | {
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| 146 | float r[2];
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[2900] | 147 | Sample3 *s = (Sample3 *)samples;
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[2902] | 148 | /*
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| 149 | // idea: use poisson distribution to generate samples
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[2900] | 150 |
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[2901] | 151 | PoissonDiscSampleGenerator poisson(mNumSamples, 1.0f);
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| 152 | Sample2 *pSamples = new Sample2[mNumSamples];
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| 153 | poisson.Generate((float *)pSamples);
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[2902] | 154 | */
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[2899] | 155 | for (int i = 0; i < mNumSamples; ++ i)
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| 156 | {
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[2902] | 157 | sHalton.GetNext(2, r);
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| 158 | //r[0] = pSamples[i].x; r[1] = pSamples[i].y;
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[2899] | 159 |
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| 160 | // create stratified samples over sphere
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[2900] | 161 | const float theta = 2.0f * acos(sqrt(1.0f - r[0]));
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| 162 | const float phi = 2.0f * M_PI * r[1];
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[2901] | 163 |
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| 164 | s[i].x = mRadius * sin(theta) * cos(phi);
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| 165 | s[i].y = mRadius * sin(theta) * sin(phi);
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| 166 | s[i].z = mRadius * cos(theta);
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| 167 | }
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[2899] | 168 |
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[2902] | 169 | //delete [] pSamples;
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[2853] | 170 | } |
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