Optimized VoxelStreamNoise with finer height range and noise shaping
Marc Gilleron
parent
c493aec343
commit
3263001c5f
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@ -26,6 +26,9 @@ real_t VoxelStreamNoise::get_height_start() const {
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}
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void VoxelStreamNoise::set_height_range(real_t hrange) {
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if (hrange < 0.1f) {
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hrange = 0.1f;
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}
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_height_range = hrange;
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}
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@ -33,6 +36,40 @@ real_t VoxelStreamNoise::get_height_range() const {
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return _height_range;
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}
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// For isosurface use cases, noise can be "shaped" by calculating only the first octave,
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// and discarding the next ones if beyond some distance away from the isosurface,
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// because then we assume next octaves won't change the sign (which crosses the surface).
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// This might reduce accuracy in some areas, but it speeds up the results.
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static inline float get_shaped_noise(OpenSimplexNoise &noise, float x, float y, float z, float threshold, float bias) {
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x /= noise.get_period();
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y /= noise.get_period();
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z /= noise.get_period();
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float sum = noise._get_octave_noise_3d(0, x, y, z);
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// A default value for `threshold` would be `persistence`
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if (sum + bias > threshold || sum + bias < -threshold) {
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// Assume next octaves will not change sign of noise
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return sum;
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}
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float amp = 1.0;
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float max = 1.0;
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int i = 0;
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while (++i < noise.get_octaves()) {
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x *= noise.get_lacunarity();
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y *= noise.get_lacunarity();
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z *= noise.get_lacunarity();
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amp *= noise.get_persistence();
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max += amp;
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sum += noise._get_octave_noise_3d(i, x, y, z) * amp;
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}
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return sum / max;
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}
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void VoxelStreamNoise::emerge_block(Ref<VoxelBuffer> out_buffer, Vector3i origin_in_voxels, int lod) {
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ERR_FAIL_COND(out_buffer.is_null());
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@ -41,77 +78,78 @@ void VoxelStreamNoise::emerge_block(Ref<VoxelBuffer> out_buffer, Vector3i origin
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OpenSimplexNoise &noise = **_noise;
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VoxelBuffer &buffer = **out_buffer;
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if (origin_in_voxels.y > _height_start + _height_range) {
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int isosurface_lower_bound = static_cast<int>(Math::floor(_height_start));
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int isosurface_upper_bound = static_cast<int>(Math::ceil(_height_start + _height_range));
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const int air_type = 0;
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const int matter_type = 1;
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if (origin_in_voxels.y >= isosurface_upper_bound) {
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// Fill with air
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if (_channel == VoxelBuffer::CHANNEL_SDF) {
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buffer.clear_channel_f(_channel, 100.0);
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}
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else if (_channel == VoxelBuffer::CHANNEL_TYPE) {
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buffer.clear_channel(_channel, 0);
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} else if (_channel == VoxelBuffer::CHANNEL_TYPE) {
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buffer.clear_channel(_channel, air_type);
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}
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} else if (origin_in_voxels.y + (buffer.get_size().y << lod) < _height_start) {
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} else if (origin_in_voxels.y + (buffer.get_size().y << lod) < isosurface_lower_bound) {
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// Fill with matter
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if (_channel == VoxelBuffer::CHANNEL_SDF) {
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buffer.clear_channel_f(_channel, -100.0);
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}
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else if (_channel == VoxelBuffer::CHANNEL_TYPE) {
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buffer.clear_channel(_channel, 1);
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} else if (_channel == VoxelBuffer::CHANNEL_TYPE) {
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buffer.clear_channel(_channel, matter_type);
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}
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} else {
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// TODO Proper noise optimization
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// Prefetching was much faster, but it introduced LOD inconsistencies into the data itself, causing cracks.
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// Need to implement it properly, or use a different noise library.
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/*FloatBuffer3D &noise_buffer = _noise_buffer;
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const int noise_buffer_step = 2;
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Vector3i noise_buffer_size = buffer.get_size() / noise_buffer_step + Vector3i(1);
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if (noise_buffer.get_size() != noise_buffer_size) {
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noise_buffer.create(noise_buffer_size);
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}
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// Cache noise at lower grid resolution and interpolate after, much cheaper
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for (int z = 0; z < noise_buffer.get_size().z; ++z) {
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for (int x = 0; x < noise_buffer.get_size().x; ++x) {
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for (int y = 0; y < noise_buffer.get_size().y; ++y) {
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float lx = origin_in_voxels.x + (x << lod) * noise_buffer_step;
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float ly = origin_in_voxels.y + (y << lod) * noise_buffer_step;
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float lz = origin_in_voxels.z + (z << lod) * noise_buffer_step;
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float n = noise.get_noise_3d(lx, ly, lz);
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noise_buffer.set(x, y, z, n);
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}
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}
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}*/
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float iso_scale = noise.get_period() * 0.1;
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//float noise_buffer_scale = 1.f / static_cast<float>(noise_buffer_step);
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Vector3i size = buffer.get_size();
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const float iso_scale = noise.get_period() * 0.1;
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const Vector3i size = buffer.get_size();
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const float height_range_inv = 1.f / _height_range;
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const float one_minus_persistence = 1.f - noise.get_persistence();
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for (int z = 0; z < size.z; ++z) {
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int lz = origin_in_voxels.z + (z << lod);
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for (int x = 0; x < size.x; ++x) {
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int lx = origin_in_voxels.x + (x << lod);
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for (int y = 0; y < size.y; ++y) {
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float lx = origin_in_voxels.x + (x << lod);
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float ly = origin_in_voxels.y + (y << lod);
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float lz = origin_in_voxels.z + (z << lod);
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int ly = origin_in_voxels.y + (y << lod);
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//float n = noise_buffer.get_trilinear(x * noise_buffer_scale, y * noise_buffer_scale, z * noise_buffer_scale);
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float n = noise.get_noise_3d(lx, ly, lz);
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float t = (ly - _height_start) / _height_range;
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float d = (n + 2.0 * t - 1.0) * iso_scale;
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if (ly < isosurface_lower_bound) {
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// Below is only matter
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if (_channel == VoxelBuffer::CHANNEL_SDF) {
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buffer.set_voxel_f(-1, x, y, z, _channel);
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} else if (_channel == VoxelBuffer::CHANNEL_TYPE) {
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buffer.set_voxel(matter_type, x, y, z, _channel);
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}
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continue;
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} else if (ly >= isosurface_upper_bound) {
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// Above is only air
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if (_channel == VoxelBuffer::CHANNEL_SDF) {
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buffer.set_voxel_f(1, x, y, z, _channel);
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} else if (_channel == VoxelBuffer::CHANNEL_TYPE) {
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buffer.set_voxel(air_type, x, y, z, _channel);
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}
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continue;
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}
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// Bias is what makes noise become "matter" the lower we go, and "air" the higher we go
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float t = (ly - _height_start) * height_range_inv;
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float bias = 2.0 * t - 1.0;
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// We are near the isosurface, need to calculate noise value
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float n = get_shaped_noise(noise, lx, ly, lz, one_minus_persistence, bias);
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float d = (n + bias) * iso_scale;
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if (_channel == VoxelBuffer::CHANNEL_SDF) {
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buffer.set_voxel_f(d, x, y, z, _channel);
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}
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else if (_channel == VoxelBuffer::CHANNEL_TYPE && d < 0) {
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buffer.set_voxel(1, x, y, z, _channel);
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} else if (_channel == VoxelBuffer::CHANNEL_TYPE && d < 0) {
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buffer.set_voxel(matter_type, x, y, z, _channel);
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}
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}
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}
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