tatrabbit / normalmap

Command line utility to convert height maps to DU-DV normal maps.

normalmap

Command line utility to convert height maps to DU-DV normal maps.

Platforms

Windows binary is provided.

Should compile and run on most modern compilers (GCC Clang, and MSVS). CMake build script is provided.

Usage

normalmap.exe infile outfile

The height will be taken from the red channel of the source image. RGBA PNGs are tested and recommended but any image type supported by stb_image should work.

The output will be an unfiltered, 8-bit unsigned du/dv map, which can be used as a normal map in rendering applications. The heightmap sampler is a 2x2 box.

The underlying normal map generation code is inherited from The GIMP and is considerably more flexible.

The following settings are provided by command line arguments:

• -f Sampler filter
  • None default
  • Sobel 3x3, 5x5
  • Prewitt 3x3, 5x5,
  • Generic 3x3, 5x5, 7x7, 9x9
• -s Scale default = 2.0
• -h Height source:
  • Luminance
  • Unbias RGB
  • Red default, Green or Blue channel
  • Alpha channel: height, height inverted
• -w Wrap output

Run the program without any arguments for details on how to use them.

In this version, you must update main.c and rebuild to change the other following settings:

• Output type:
  • du/dv 8-bit signed default, 8-bit unsigned, 16-bit signed, 16-bit unsigned
  • true "normalized" normal

Note that the effect of du/dv output being unnormalized is that normal vectors constructed by sampling the map will require normalization in your shader or image loader, which means in turn that the effect of the scale parameter above is less pronounced than it would be otherwise.