[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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| 8 |
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| 9 | SampleGenerator::SampleGenerator(int numSamples, float radius):
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| 10 | mNumSamples(numSamples), mRadius(radius)
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[3230] | 11 | {
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| 12 | mHalton = new HaltonSequence(2);
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| 13 | }
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[2853] | 14 |
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| 15 |
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[3230] | 16 | SampleGenerator::~SampleGenerator()
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| 17 | {
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| 18 | DEL_PTR(mHalton);
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| 19 | }
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| 20 |
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| 21 |
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[3227] | 22 | PoissonDiscSampleGenerator2D::PoissonDiscSampleGenerator2D(int numSamples, float radius):
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[3230] | 23 | SampleGenerator(numSamples, radius)
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[2853] | 24 | {}
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| 25 |
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| 26 |
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[3227] | 27 | void PoissonDiscSampleGenerator2D::Generate(float *samples) const
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[2853] | 28 | {
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[3233] | 29 | // Poisson disc sampling generator using relaxation
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| 30 | // dart-throwing as proposed by McCool et al.
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| 31 | // the min distance requirement is relaxed if we are not
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[2930] | 32 | // able to place any dart for a number of tries
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[3233] | 33 | // the solution is a possion sampling with respect
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| 34 | // to the adjusted min distance
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| 35 | // this sampling scheme has the benefit that it is hierarchical
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| 36 | int maxTries = 1000;
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[3234] | 37 | const float f_reduction = 0.95f;
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[3233] | 38 |
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[2853] | 39 | float r[2];
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| 40 |
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[3234] | 41 | // the maximal possible radius: our radius is a fraction of this radius
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| 42 | // this is used as a measure of the quality of distribution of the point samples
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| 43 | const float rmax = 2.0f * mRadius * sqrt(1.0f / (2.0f * sqrt(3.0f) * mNumSamples));
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| 44 |
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[2853] | 45 | // generates poisson distribution on disc
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[3234] | 46 | // start with some thresholds: all samples lie on the circumference of circle
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[3233] | 47 |
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[3234] | 48 | float minDist = 2.0f * rmax;
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[2930] | 49 | float sqrMinDist = minDist * minDist;
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[2853] | 50 |
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[3234] | 51 | int tries = 0;
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| 52 |
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[2853] | 53 | //cout << "minDist before= " << minDist << endl;
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[2900] | 54 | Sample2 *s = (Sample2 *)samples;
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[2853] | 55 |
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[2930] | 56 | // check if on disc
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[2853] | 57 | for (int i = 0; i < mNumSamples; ++ i)
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| 58 | {
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| 59 | // repeat until valid sample was found
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| 60 | while (1)
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| 61 | {
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[3234] | 62 | // q: should we use halton or does it conflict with the poisson disc properties?
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| 63 | r[0] = RandomValue(0, 1); r[1] = RandomValue(0, 1);
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| 64 | //mHalton->GetNext(r);
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[2853] | 65 |
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[2930] | 66 | // scale to -1 .. 1
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[2853] | 67 | const float rx = r[0] * 2.0f - 1.0f;
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| 68 | const float ry = r[1] * 2.0f - 1.0f;
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| 69 |
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| 70 | // check if in disk, else exit early
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[3103] | 71 | const float distanceSquared = rx * rx + ry * ry;
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| 72 |
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| 73 | if ((rx * rx + ry * ry > mRadius * mRadius)
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[3162] | 74 | // also avoid case that sample exactly in center
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[3227] | 75 | //|| (distanceSquared <= 1e-3f)
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[3103] | 76 | )
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[2853] | 77 | continue;
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| 78 |
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| 79 | bool sampleValid = true;
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| 80 |
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| 81 | // check poisson property
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| 82 | for (int j = 0; ((j < i) && sampleValid); ++ j)
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| 83 | {
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| 84 | const float dist =
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[2930] | 85 | (s[j].x - rx) * (s[j].x - rx) +
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| 86 | (s[j].y - ry) * (s[j].y - ry);
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[2853] | 87 |
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[2930] | 88 | if (dist < sqrMinDist)
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[2853] | 89 | sampleValid = false;
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| 90 | }
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| 91 |
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| 92 | if (sampleValid)
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| 93 | {
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[2900] | 94 | s[i].x = rx;
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| 95 | s[i].y = ry;
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[2853] | 96 | break;
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| 97 | }
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| 98 |
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[3234] | 99 | ++ tries;
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| 100 |
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[2873] | 101 | if (tries > maxTries)
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[2853] | 102 | {
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[3234] | 103 | minDist *= f_reduction;
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| 104 | sqrMinDist = minDist * minDist;
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| 105 |
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| 106 | maxTries += 1000;
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[2853] | 107 | }
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| 108 | }
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| 109 | }
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| 110 |
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[3235] | 111 | //cout << "minDist after= " << (float)minDist / mNumSamples<< " #tries: " << tries << endl;
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[2898] | 112 | }
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| 113 |
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| 114 |
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[3227] | 115 | RandomSampleGenerator2D::RandomSampleGenerator2D(int numSamples, float radius):
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[3230] | 116 | SampleGenerator(numSamples, radius)
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[2898] | 117 | {}
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| 118 |
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| 119 |
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[3227] | 120 | void RandomSampleGenerator2D::Generate(float *samples) const
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[2898] | 121 | {
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[2900] | 122 | Sample2 *s = (Sample2 *)samples;
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| 123 |
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[2903] | 124 | int numSamples = 0;
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[2898] | 125 |
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[2930] | 126 | float r[2];
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| 127 |
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[2903] | 128 | while (numSamples < mNumSamples)
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[2898] | 129 | {
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[3230] | 130 | mHalton->GetNext(r);
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[2930] | 131 |
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| 132 | const float rx = r[0] * 2.0f - 1.0f;
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| 133 | const float ry = r[1] * 2.0f - 1.0f;
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[2898] | 134 |
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[2903] | 135 | // check if in disk, else exit early
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| 136 | if (rx * rx + ry * ry > mRadius * mRadius)
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| 137 | continue;
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[2898] | 138 |
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[2903] | 139 | s[numSamples].x = rx;
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| 140 | s[numSamples].y = ry;
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[2898] | 141 |
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[2903] | 142 | ++ numSamples;
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| 143 | }
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[2899] | 144 | }
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| 145 |
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| 146 |
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[3227] | 147 | SphericalSampleGenerator3D::SphericalSampleGenerator3D(int numSamples, float radius):
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[2899] | 148 | SampleGenerator(numSamples, radius)
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| 149 | {}
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| 150 |
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| 151 |
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[3227] | 152 | void SphericalSampleGenerator3D::Generate(float *samples) const
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[2899] | 153 | {
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| 154 | float r[2];
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[2900] | 155 | Sample3 *s = (Sample3 *)samples;
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| 156 |
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[2899] | 157 | for (int i = 0; i < mNumSamples; ++ i)
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| 158 | {
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[2903] | 159 | r[0] = RandomValue(0, 1);
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| 160 | r[1] = RandomValue(0, 1);
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[2930] | 161 |
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[2899] | 162 | // create stratified samples over sphere
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[2900] | 163 | const float theta = 2.0f * acos(sqrt(1.0f - r[0]));
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| 164 | const float phi = 2.0f * M_PI * r[1];
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[2901] | 165 |
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| 166 | s[i].x = mRadius * sin(theta) * cos(phi);
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| 167 | s[i].y = mRadius * sin(theta) * sin(phi);
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| 168 | s[i].z = mRadius * cos(theta);
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| 169 | }
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[2930] | 170 | }
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[2899] | 171 |
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[2930] | 172 |
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[3227] | 173 | QuadraticDiscSampleGenerator2D::QuadraticDiscSampleGenerator2D(int numSamples, float radius):
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[3247] | 174 | //PoissonDiscSampleGenerator2D(numSamples, radius)
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| 175 | RandomSampleGenerator2D(numSamples, radius)
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[2930] | 176 | {}
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| 177 |
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| 178 |
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[3227] | 179 | void QuadraticDiscSampleGenerator2D::Generate(float *samples) const
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[2930] | 180 | {
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[2954] | 181 | #if 0
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[2930] | 182 | float r[2];
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| 183 | Sample2 *s = (Sample2 *)samples;
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| 184 |
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| 185 | for (int i = 0; i < mNumSamples; ++ i)
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| 186 | {
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[3230] | 187 | mHalton->GetNext(r);
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[2930] | 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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[3247] | 196 | //PoissonDiscSampleGenerator2D::Generate(samples);
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| 197 | RandomSampleGenerator2D::Generate(samples);
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[3229] | 198 |
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[2954] | 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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