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Some experiments with realtime water simulation on heightfield terrains, using OpenGL 4.3.
- C++11 (using mainly Visual Studio 2013)
- OpenGL 4.3
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ezEngine (File IO, Memory Management, Basic Math, Window creation, Input, ...)
- A while ago I took a minor part in its development
- GLEW (OpenGL function wrangler)
- AntTweakBar (DropIn solution for tweak variables)
- stb_image (For simplistic texture loading)
- The most of the sources were already GPU orientated, but almost none of them used the features of modern hardware. I rearranged nearly everything and make very often use of Compute Shader, Indirect Draw and other modern features.
- Simulation in fixed timesteps - each frame the simulation steps n times, number of steps per second is constant.
- Much FP32 :( - everything else limits the simulation or makes it explode
Heightfield water: "Column base Water simulation" Water in column, each column connected to 4 neighbors with "virtual pipes". Outgoing flow in each of the 4 directions is saved per heightfield-pixel.
Idea relatively good explained and why the outgoing-flow thing is so important can be found here. While being not very detailed Theses slides can give a very good overview what this is all about.
- Outgoing flow RGBA32F
- Two passes atm: Compute outgoing flow, Apply flow
- Output flow map on the fly in second pass (RG16f)
- Simple Forward renderer
- Gamma correct Rendering - it is really simple, try it if you haven't already!
- The definite Fog ;)
- One directional light atm
- Texture Blending
- Fresnel is great everywhere!
- Screenspace Tesselation inspired by this. Solved crack problem with triangle patches instead, no fine displacement map as described in the paper. Uses instancing, only 3 draw calls (one per Patch - full, one transition, two transitions)
- Reuses grid from terrain. Almost the same geometry setup, but cull patches under terrain in Control shader
- tossed informations mainly from this article and from this thread around until I something came out I was confident with
- Flow from flowmap
- Some Foam for fast water (also influenced by flow map)
- ScreenSpace Reflections
- since the water has arbitrary slopes and levels!
- accelerated with a custom "MaxMap" for faster raytracing
Athmospheric scattering, rendered into a fairly low res cubemap (doesn't really need many pixels!). Since I honestly didn't want to spend much time on this complicated topic, I use an existing implementation described by Florian Boesch here and did some adjustments to fit my needs.
Filmic Tonemapping with simple Luminance adaptation.
- Using some fancy C++11 feature
- Renderer is based on some gl wrapper classes that are not meant to abstract OpenGL but just to make things easier
(List not complete, mostly a memory aid to my self)
- Add/Remove water with mouse Update: Possible now, but also happens when doing sth. in the TweakBar which is terribly annoying
- Better grid topology (mediocre atm when it comes to water intersection & popping reduction)
- Compute Irradiance Spherical Harmonic from Skybox to light water and terrain
- Better fine waves (since simulation has its limits...) - simple but confusing normalmap atm
- Grass
- Culling
- Other Vegetation?
- Clouds
- Rain
- Deferred MSAA sounds like a good idea
- Fancy erosion stuff
- Wind
- Rain/Evaporation
- Water Spray?
- Moar sliders - make more stuff tweakable, still many magic numbers in code
- Less sliders - make parameters more interdependant, compute stuff; make things tweakable the EASY way
- Good default values
- More OpenGL wrapper stuff - especially these Samplers are annoying!
- Better specification of dependencies to ezEngine ** Should only use major releases