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exr_decode_example

README.md

Exr Decode Example

Renders a stylised 3D terrain, drawn with height lines.

The terrain height map is loaded as a 32bit float .exr image, and stored into a R32Sfloat GPU image resource.

  • If the image is modified and saved while the app is running, it will hot-reload the modified image, and draw the modified terrain.

  • Height lines are anti-aliased, and of constant thickness, regardless of how far or close to the camera they are -- this is possible by using a technique described by Evan Wallace in: https://www.madebyevan.com/shaders/grid/

  • While this example loads a 32bit float grayscale (single channel) image, the OpenEXR image decoder in le_exr can load many more .exr image types: RGB, RGBA, 16bit and 32bit

  • This example depends on some image assets not contained in the main repository but these assets can be downloaded simply enough -- see build instructions, below.

Camera controls:

  • key O: toggle camera orthograhic / perspective projection
  • key Z: reset camera
  • key X: toggle camera orbit axis - when rotating, the camera either orbits around a point or rotates in-place
  • mouse left button drag: rotate camera (when the camera is grabbed outside the center, tilt camera)
  • shift+left button drag: - or - mouse right button drag: dolly camera (move forwards/backwards)
  • ctrl + left button drag: - or - mouse middle button drag: pan camera up/down,left/right

Techniques used:

  • le_exr - decode OpenEXR images
  • using le_resource_manager to simplify image loading
  • add OpenEXR decode capability to le_resource_manager via a one-liner (see line 75 in exr_decode_example_app.cpp).
  • image hot-reloading
  • depth testing
  • rendering isolines
  • constant-width aliased lines (see ./resources/shaders/isolines.frag)

screenshot

Build instructions

Download image assets via the bash script in the project root folder. (To keep the Island code repository slim, these image assets are hosted outside of the main repo.)

./download_assets.sh

Configure build environment using CMake:

mkdir build 
cd build
cmake -G Ninja ..

Note that if you are using Qt Creator you may skip manually setting up the build environment, and simply open the project CMakeLists.txt using Qt Creator.

Build using Ninja:

ninja

Run application:

cd bin
./Island-ExrDecodeExample