[2853] | 1 | #include "SampleGenerator.h"
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[2903] | 2 | #include "common.h"
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[2853] | 3 |
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[2901] | 4 |
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[2853] | 5 | using namespace std;
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[2903] | 6 | using namespace CHCDemoEngine;
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[2853] | 7 |
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[2930] | 8 | HaltonSequence SphericalSampleGenerator3::sHalton;
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| 9 | HaltonSequence PoissonDiscSampleGenerator2::sHalton;
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| 10 | HaltonSequence RandomSampleGenerator2::sHalton;
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| 11 | HaltonSequence QuadraticDiscSampleGenerator2::sHalton;
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[2853] | 12 |
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[2901] | 13 |
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[2853] | 14 | SampleGenerator::SampleGenerator(int numSamples, float radius):
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| 15 | mNumSamples(numSamples), mRadius(radius)
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| 16 | {}
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| 17 |
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| 18 |
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[2930] | 19 | PoissonDiscSampleGenerator2::PoissonDiscSampleGenerator2(int numSamples, float radius):
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[2853] | 20 | SampleGenerator(numSamples, radius)
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| 21 | {}
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| 22 |
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| 23 |
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[2930] | 24 | void PoissonDiscSampleGenerator2::Generate(float *samples) const
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[2853] | 25 | {
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[2930] | 26 | // this is a hacky poisson sampling generator which does random dart-throwing on a disc.
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| 27 | // as a savety criterium, the min distance requirement is relaxed if we are not
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| 28 | // able to place any dart for a number of tries
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[2873] | 29 | // the solution is a possion sampling with respect to the adjusted min distance
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| 30 | // better solutions have been proposed, i.e., using hierarchical sampling
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[3221] | 31 | const int maxTries = 1000;
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[2873] | 32 | const float f_reduction = 0.9f;
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| 33 |
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[2903] | 34 | //static HaltonSequence halton;
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[2853] | 35 | float r[2];
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| 36 |
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| 37 | // generates poisson distribution on disc
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[2930] | 38 | // start with some threshold. best case: all samples lie on the circumference
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| 39 | //const float minDist = 2.0f * mRadius / sqrt((float)mNumSamples);
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| 40 | const float eps = 0.2f;
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| 41 | const float minDist = 2.0f * mRadius * M_PI * (1.0f - eps) / (float)mNumSamples;
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| 42 | float sqrMinDist = minDist * minDist;
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[2853] | 43 |
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| 44 | //cout << "minDist before= " << minDist << endl;
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[2900] | 45 | Sample2 *s = (Sample2 *)samples;
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[2853] | 46 |
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[2930] | 47 | int totalTries = 0;
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| 48 |
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| 49 | // check if on disc
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[2853] | 50 | for (int i = 0; i < mNumSamples; ++ i)
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| 51 | {
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[2930] | 52 | int tries = 0;
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[2853] | 53 |
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| 54 | // repeat until valid sample was found
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| 55 | while (1)
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| 56 | {
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| 57 | ++ tries;
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| 58 | ++ totalTries;
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| 59 |
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[2930] | 60 | // note: should use halton, but seems somewhat broken
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| 61 | //r[0] = RandomValue(.0f, mRadius);
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| 62 | //r[1] = RandomValue(.0f, mRadius);
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| 63 | sHalton.GetNext(2, r);
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[2853] | 64 |
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[2930] | 65 | // scale to -1 .. 1
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[2853] | 66 | const float rx = r[0] * 2.0f - 1.0f;
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| 67 | const float ry = r[1] * 2.0f - 1.0f;
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| 68 |
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| 69 | // check if in disk, else exit early
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[3103] | 70 | const float distanceSquared = rx * rx + ry * ry;
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| 71 |
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| 72 | if ((rx * rx + ry * ry > mRadius * mRadius)
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[3162] | 73 | // also avoid case that sample exactly in center
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[3103] | 74 | || (distanceSquared <= 1e-3f)
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| 75 | )
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[2853] | 76 | continue;
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| 77 |
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| 78 | bool sampleValid = true;
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| 79 |
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| 80 | // check poisson property
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| 81 | for (int j = 0; ((j < i) && sampleValid); ++ j)
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| 82 | {
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| 83 | const float dist =
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[2930] | 84 | (s[j].x - rx) * (s[j].x - rx) +
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| 85 | (s[j].y - ry) * (s[j].y - ry);
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[2853] | 86 |
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[2930] | 87 | if (dist < sqrMinDist)
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[2853] | 88 | sampleValid = false;
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| 89 | }
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| 90 |
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| 91 | if (sampleValid)
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| 92 | {
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[2900] | 93 | s[i].x = rx;
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| 94 | s[i].y = ry;
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[2853] | 95 | break;
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| 96 | }
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| 97 |
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[2873] | 98 | if (tries > maxTries)
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[2853] | 99 | {
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[2930] | 100 | sqrMinDist *= f_reduction;
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[2853] | 101 | tries = 0;
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| 102 | }
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| 103 | }
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| 104 | }
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| 105 |
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[2930] | 106 | //cout << "minDist after= " << sqrt(sqrMinDist) << " #tries: " << totalTries << endl;
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[2898] | 107 | }
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| 108 |
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| 109 |
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[2930] | 110 | RandomSampleGenerator2::RandomSampleGenerator2(int numSamples, float radius):
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[2898] | 111 | SampleGenerator(numSamples, radius)
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| 112 | {}
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| 113 |
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| 114 |
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[2930] | 115 | void RandomSampleGenerator2::Generate(float *samples) const
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[2898] | 116 | {
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[2900] | 117 | Sample2 *s = (Sample2 *)samples;
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| 118 |
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[2903] | 119 | int numSamples = 0;
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[2898] | 120 |
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[2930] | 121 | float r[2];
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| 122 |
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[2903] | 123 | while (numSamples < mNumSamples)
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[2898] | 124 | {
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[2930] | 125 | //r[0] = RandomValue(-mRadius, mRadius);
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| 126 | //r[1] = RandomValue(-mRadius, mRadius);
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| 127 | sHalton.GetNext(2, r);
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| 128 |
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| 129 | const float rx = r[0] * 2.0f - 1.0f;
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| 130 | const float ry = r[1] * 2.0f - 1.0f;
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[2898] | 131 |
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[2903] | 132 | // check if in disk, else exit early
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| 133 | if (rx * rx + ry * ry > mRadius * mRadius)
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| 134 | continue;
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[2898] | 135 |
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[2903] | 136 | s[numSamples].x = rx;
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| 137 | s[numSamples].y = ry;
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[2898] | 138 |
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[2903] | 139 | ++ numSamples;
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| 140 | }
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[2899] | 141 | }
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| 142 |
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| 143 |
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[2930] | 144 | SphericalSampleGenerator3::SphericalSampleGenerator3(int numSamples, float radius):
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[2899] | 145 | SampleGenerator(numSamples, radius)
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| 146 | {}
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| 147 |
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| 148 |
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[2930] | 149 | void SphericalSampleGenerator3::Generate(float *samples) const
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[2899] | 150 | {
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| 151 | float r[2];
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[2900] | 152 | Sample3 *s = (Sample3 *)samples;
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| 153 |
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[2899] | 154 | for (int i = 0; i < mNumSamples; ++ i)
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| 155 | {
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[2903] | 156 | r[0] = RandomValue(0, 1);
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| 157 | r[1] = RandomValue(0, 1);
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[2930] | 158 |
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[2903] | 159 | //sHalton.GetNext(2, r);
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[2899] | 160 |
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| 161 | // create stratified samples over sphere
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[2900] | 162 | const float theta = 2.0f * acos(sqrt(1.0f - r[0]));
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| 163 | const float phi = 2.0f * M_PI * r[1];
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[2901] | 164 |
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| 165 | s[i].x = mRadius * sin(theta) * cos(phi);
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| 166 | s[i].y = mRadius * sin(theta) * sin(phi);
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| 167 | s[i].z = mRadius * cos(theta);
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| 168 | }
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[2930] | 169 | }
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[2899] | 170 |
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[2930] | 171 |
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| 172 | QuadraticDiscSampleGenerator2::QuadraticDiscSampleGenerator2(int numSamples, float radius):
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| 173 | SampleGenerator(numSamples, radius)
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| 174 | {}
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| 175 |
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| 176 |
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| 177 | void QuadraticDiscSampleGenerator2::Generate(float *samples) const
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| 178 | {
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[2954] | 179 | #if 0
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[2930] | 180 | float r[2];
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| 181 | Sample2 *s = (Sample2 *)samples;
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| 182 |
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| 183 | for (int i = 0; i < mNumSamples; ++ i)
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| 184 | {
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| 185 | //r[0] = samples[i * 2];
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| 186 | //r[1] = samples[i * 2 + 1];
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| 187 | sHalton.GetNext(2, r);
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| 188 |
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| 189 | // create samples over disc: the sample density
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| 190 | // decreases quadratically with the distance to the origin
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| 191 | s[i].x = mRadius * r[1] * sin(2.0f * M_PI * r[0]);
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| 192 | s[i].y = mRadius * r[1] * cos(2.0f * M_PI * r[0]);
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[2954] | 193 | }
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| 194 | #else
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[2930] | 195 |
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[2954] | 196 | PoissonDiscSampleGenerator2 poisson(mNumSamples, 1.0f);
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| 197 | poisson.Generate(samples);
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| 198 |
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| 199 | Sample2 *s = (Sample2 *)samples;
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| 200 |
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| 201 | // multiply with lenght to get quadratic dependence on the distance
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| 202 | for (int i = 0; i < mNumSamples; ++ i)
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| 203 | {
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[2955] | 204 | Sample2 &spl = s[i];
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[2954] | 205 |
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| 206 | float len = sqrt(spl.x * spl.x + spl.y * spl.y);
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| 207 | spl.x *= len * mRadius;
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| 208 | spl.y *= len * mRadius;
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[2930] | 209 | }
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[2954] | 210 | #endif
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[2853] | 211 | } |
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