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Display an error when a noise parameter has too many octaves (#9394)

Display an error and throw exception when one or more octaves of
a noise has spread < 1, causing random looking broken noise.
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paramat committed Feb 12, 2020
1 parent 2d5e0ce commit c2f48eab4dfd352c391266b858378dd032d84a0f
Showing with 14 additions and 5 deletions.
  1. +14 −5 src/noise.cpp
@@ -503,23 +503,32 @@ void Noise::setOctaves(int octaves)

void Noise::resizeNoiseBuf(bool is3d)
{
//maximum possible spread value factor
// Maximum possible spread value factor
float ofactor = (np.lacunarity > 1.0) ?
pow(np.lacunarity, np.octaves - 1) :
np.lacunarity;

// noise lattice point count
// Noise lattice point count
// (int)(sz * spread * ofactor) is # of lattice points crossed due to length
float num_noise_points_x = sx * ofactor / np.spread.X;
float num_noise_points_y = sy * ofactor / np.spread.Y;
float num_noise_points_z = sz * ofactor / np.spread.Z;

// protect against obviously invalid parameters
// Protect against obviously invalid parameters
if (num_noise_points_x > 1000000000.f ||
num_noise_points_y > 1000000000.f ||
num_noise_points_z > 1000000000.f)
num_noise_points_y > 1000000000.f ||
num_noise_points_z > 1000000000.f)
throw InvalidNoiseParamsException();

// Protect against an octave having a spread < 1, causing broken noise values
if (np.spread.X / ofactor < 1.0f ||
np.spread.Y / ofactor < 1.0f ||
np.spread.Z / ofactor < 1.0f) {
errorstream << "A noise parameter has too many octaves: "
<< np.octaves << " octaves" << std::endl;
throw InvalidNoiseParamsException("A noise parameter has too many octaves");
}

// + 2 for the two initial endpoints
// + 1 for potentially crossing a boundary due to offset
size_t nlx = (size_t)std::ceil(num_noise_points_x) + 3;

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