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prideout/heman

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This toy project is a tiny MIT-licensed C library of image utilities for dealing with height maps, normal maps, distance fields, and the like. It has a very low-level API, where an "image" is simply a flat array of floats. There are no dependencies and only one header file.

Heman can do stuff like this:

  • Create a random height field using simplex noise and FBM.
  • Generate a normal map from a height map.
  • Compute ambient occlusion from a height map.
  • Generate a signed distance field (SDF).
  • Export a 3D mesh in PLY format.
  • Apply a color gradient to a heightmap.
  • Generate a color gradient, given a list of control points.
  • Compute diffuse lighting with an infinite light source.
  • Generate a nicely-distributed list of points according to a density field.

Heman implements some really nice 21st-century algorithms:

  • Ambient occlusion is generated using Sean Barrett's efficient method that makes 16 sweeps over the height field.
  • Distance field computation uses the beautiful algorithm from Distance Transforms of Sampled Functions (Felzenszwalb and Huttenlocher).
  • Density field samples are generated using Robert Bridson's Fast Poisson Disk Sampling in Arbitrary Dimensions.

Example

The images at the top were generated from code that looks like this:

// Generate an island shape using simplex noise and a distance field.
heman_image* elevation = heman_generate_island_heightmap(1024, 1024, rand());

// Compute ambient occlusion from the height map.
heman_image* occ = heman_lighting_compute_occlusion(elevation);

// Visualize the normal vectors.
heman_image* normals = heman_lighting_compute_normals(elevation);

// Apply a color gradient.
heman_image* gradient = heman_color_create_gradient(...);
heman_image* albedo = heman_color_apply_gradient(elevation, -0.5, 0.5, grad);

// Apply diffuse lighting.
heman_image* final = heman_lighting_apply(elevation, albedo, ...);

For the unabridged version, see test_lighting() in test/test_heman.c.

Building OpenMP

curl -L -O https://github.com/llvm/llvm-project/releases/download/llvmorg-12.0.0/openmp-12.0.0.src.tar.xz
tar -xvf openmp-12.0.0.src.tar.xz ; rm openmp-12.0.0.src.tar.xz
cd openmp-12.0.0.src
cmake . -DLIBOMP_ENABLE_SHARED=OFF -DLIBOMP_INSTALL_ALIASES=OFF -DCMAKE_OSX_ARCHITECTURES=x86_64
sudo make install