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Diffstat (limited to 'o3d/command_buffer/samples/bubble/perlin_noise.cc')
| -rw-r--r-- | o3d/command_buffer/samples/bubble/perlin_noise.cc | 107 |
1 files changed, 107 insertions, 0 deletions
diff --git a/o3d/command_buffer/samples/bubble/perlin_noise.cc b/o3d/command_buffer/samples/bubble/perlin_noise.cc new file mode 100644 index 0000000..f69f527 --- /dev/null +++ b/o3d/command_buffer/samples/bubble/perlin_noise.cc @@ -0,0 +1,107 @@ +/* + * Copyright 2009, Google Inc. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are + * met: + * + * * Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * * Redistributions in binary form must reproduce the above + * copyright notice, this list of conditions and the following disclaimer + * in the documentation and/or other materials provided with the + * distribution. + * * Neither the name of Google Inc. nor the names of its + * contributors may be used to endorse or promote products derived from + * this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR + * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT + * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT + * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE + * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + + +// This file contains the implementation of the Perlin noise generator. + +#include <stdlib.h> +#include "command_buffer/common/cross/logging.h" +#include "command_buffer/samples/bubble/perlin_noise.h" +#include "command_buffer/samples/bubble/utils.h" + +namespace o3d { +namespace command_buffer { + +PerlinNoise2D::PerlinNoise2D(unsigned int frequency) + : frequency_(frequency), + permutation_(new unsigned int[2*frequency]), + gradients_(new Float2[frequency]) { +} + +void PerlinNoise2D::Initialize(unsigned int *seed) { + // Initialize the gradients table with a random unit direction. + // Initialize the permutation table to be the identity. + for (unsigned int i = 0; i < frequency_; ++i) { + float theta = Randf(0.f, 2.f * kPi, seed); + gradients_[i] = Float2(cosf(theta), sinf(theta)); + permutation_[i] = i; + } + // Generate the permutation table by switching each element with a further + // element. Also duplicate the permutation table so that constructs like + // permutation[x + permutation[y]] work without additional modulo. + for (unsigned int i = 0; i < frequency_; ++i) { + unsigned int j = i + (rand_r(seed) % (frequency_ - i)); + unsigned int tmp = permutation_[j]; + permutation_[j] = permutation_[i]; + permutation_[i] = tmp; + permutation_[i + frequency_] = tmp; + } +} + +void PerlinNoise2D::Generate(unsigned int width, + unsigned int height, + float *texture) { + for (unsigned int y = 0; y < height; ++y) { + for (unsigned int x = 0; x < width; ++x) { + // The texture is decomposed into a lattice of frequency_ points in each + // direction. A (x, y) point falls between 4 lattice vertices. + // (xx, yy) are the coordinate of the bottom left lattice vertex + // corresponding to an (x, y) image point. + unsigned int xx = x * frequency_ / width; + unsigned int yy = y * frequency_ / height; + // xt and yt are the barycentric coordinates of the (x, y) point relative + // to the vertices (between 0 and 1). + float xt = 1.f/width * ((x * frequency_) % width); + float yt = 1.f/height * ((y * frequency_) % height); + // contribution of each lattice vertex to the point value. + float contrib[4]; + for (unsigned int y_offset = 0; y_offset < 2; ++y_offset) { + for (unsigned int x_offset = 0; x_offset < 2; ++x_offset) { + unsigned int index = permutation_[xx + x_offset] + y_offset + yy; + DCHECK_LT(index, frequency_ * 2); + Float2 gradient = gradients_[permutation_[index]]; + contrib[y_offset*2+x_offset] = gradient.first * (xt - x_offset) + + gradient.second * (yt - y_offset); + } + } + // We interpolate between the vertex contributions using a smooth step + // function of the barycentric coordinates. + float xt_smooth = SmoothStep(xt); + float yt_smooth = SmoothStep(yt); + float contrib_bottom = Lerp(xt_smooth, contrib[0], contrib[1]); + float contrib_top = Lerp(xt_smooth, contrib[2], contrib[3]); + *texture++ = Lerp(yt_smooth, contrib_bottom, contrib_top); + } + } +} + +} // namespace command_buffer +} // namespace o3d |